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Li, Xiangqian. "Task-switching costs without task-switching." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/8962/.
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It has been suggested that task-switching costs can be eliminated if participants memorise all stimulus-response mappings thereby avoiding task-switching altogether (Dreisbach, Goschke & Haider, 2006, 2007; Dreisbach & Haider, 2008). This has been labelled the “Look-Up Table” (LUT) approach. It has also been suggested that the LUT approach could potentially explain why animals such as monkeys (Stoet & Snyder, 2003; Avdagic et al., 2013) and pigeons (Castro & Wasserman, 2016; Meier, Lea & McLaren 2016) were able to perform task-switching without showing any task-switching costs (Dreisbach, et al., 2006, 2007; Dreisbach & Haider, 2008; Forrest, Monsell & Mclaren, 2014). In a series of eight experiments the following two questions were addressed: (1) Why do some participants show significant task-switching costs even when they do not switch between tasks (e.g., Forrest, Monsell & Mclaren, 2014)? (2) Can the LUT approach explain the absence of task-switching costs? In an attempt to answer both questions different sources of human task-switching costs are investigated in eight behavioural experiments. Chapter 1 provides an overview of different task-switching paradigms and accounts to explain task-switching costs. Chapter 2 summarises previous attempts to remove human task-switching costs. Evidence for the absence of task-switching costs in animals is also introduced. Following up on previous studies that suggested the LUT approach can explain the absence of task-switching costs, I conducted two task-switching experiments using visual tasks (i.e., colour task and shape task) with bivalent stimuli in an attempt to re-examine the conclusions of previous LUT studies (i.e., Dreisbach, et al., 2006, 2007; Dreisbach & Haider, 2008; Forrest, Monsell & Mclaren, 2014). The results in Chapter 2 indicate that human participants cannot always eliminate task-switching costs and do not always apply the LUT approach when the task-switching strategy is controlled. Therefore, the experiments in Chapter 3 and 4 sought to ascertain the requirements for eliminating task-switching costs when using the LUT approach. The experiments in Chapter 3 applied visual tasks where each task had a different stimulus-set. Experiments in Chapter 4 applied two classical mathematical tasks (i.e., big/small task, odd/even task) and used Chinese numbers as stimuli. The results of the experiments in Chapters 3 and 4 suggest that human participants must be able to give the correct answer without processing task-relevant features from the stimuli in order to eliminate task-switching costs. In the experiment of Chapter 5 the cue-stimulus-response mappings from Experiments 2.1 and 2.2 were rearranged so that switching between conventional tasks and rules became impossible. The results suggest that task-relevant features can trigger interferences thereby causing “task-switching costs” even when participants do not switch between tasks. In Chapter 7, I compare a modified interference account, introduced in Chapter 5, with the compound retrieval account (e.g., Logan & Schneider, 2010) and associative learning account (Forrest et al., 2014; Meier et al., 2016) in order to explain why human participants show task-switching costs even when they do not switch between tasks. I conclude that the modified interference account provides an alternative explanation. It has been proposed that only humans are affected by strong and long-lasting interference from previous trials during task-switching. As a consequence, this interference may explain why human participants consistently show task-switching costs whereas monkeys and pigeons show no task-switching costs.
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Brand, Sarah Louise. "Task switching and distractibility." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1444120/.
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In this thesis I examined the effects of task switching on people's ability to ignore irrelevant distractors. Load theory proposes that distractor interference critically depends on the availability of executive control to minimise the effects of irrelevant stimuli (e.g. Lavie, 2000). Much work on task switching suggests that task switching demands executive control in order to prepare for and implement a switch between tasks (e.g. Monsell, 2003 Rubinstein, Meyer, & Evans, 2001). I therefore hypothesised that the executive demand of a task switch will result in reduced ability to reject irrelevant distractors in selective attention tasks. The research reported provided support for this hypothesis by showing that task switching results in greater distractor interference as measured with the "flanker task" (e.g. Eriksen & Eriksen, 1974) and with the attentional capture task (e.g. Theeuwes, 1990), even when there was no overlap between the stimuli and responses for the two tasks, and when task-repeated and switch trials were presented within the same block (in AAABBB designs). This research also showed that dissociable executive demands were involved in switching tasks (AAABBB), compared with mixing tasks (ABAB versus AAA), and these executive demands were found to control rejection of distractors in the flanker task and attentional capture task, respectively. In addition, task switching reduced internal distraction by task-unrelated thoughts. The contrast between the effects of task switching on internal versus external sources of distraction further supported the involvement of executive control in task switching. Finally, individual differences in operational span capacity predicted the magnitude of task switching costs and flanker interference effects, suggesting the involvement of executive control in both abilities. Overall, this research highlights a new consequence of task switching on selective attention and distractibility, supporting predictions derived from prevalent views on the role of executive control in task switching and selective attention.
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Perry, B. H. S. "Component processes in task switching." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302498.
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Cooper, Stephen. "Task switching and response processes." Thesis, Bangor University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494187.
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When switching between tasks, participants are sometimes required to use different response sets for each task: So, task switch and response set switch are commonly confounded. Eleven experiments divided into three series examined transitions of response within a linear four-finger arrangement. The first series examined cued grouping by hand or finger equivalence in both single task and task switching designs. The second considered the effect upon transitions of response when full repetition of the stimulus was included in the design. Results showed that part of the task switch cost is associated with switching between response sets, particularly those of hand.
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Longman, Cai Stephen. "Spatial attention in task switching." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/15729.
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This thesis is a systematic investigation of preparatory reorienting of task-relevant spatial attention. Task switching experiments typically report a performance overhead when the current task is different to that performed on the previous trial relative to when the task repeats. This ‘switch cost’ tends to reduce as participants are given more time to prepare (consistent with an active reconfiguration process) but a ‘residual’ switch cost usually remains even at very long preparation intervals (often interpreted as evidence of carryover of response selection parameters from the previous trial which are immune to preparation). Although attentional selection of perceptual attributes is often considered to be part of task-set and is included in some models of task-set control, little research has investigated the dynamics of this component in detail. Over a series of seven experiments in which tasks were consistently mapped to screen locations, eye-tracking was used to systematically investigate task-relevant spatial selection of perceptual attributes during the preparation interval and early after stimulus onset. Experiment 1 revealed a switch-induced delay in appropriate attention orientation and a measure of ‘attentional inertia’ which could not be explained by task-independent re-orienting to locations or low-level oculomotor phenomena but were markers of task-relevant spatial selection. Experiment 2 provided a sensitive measure of both of these attentional handicaps and demonstrated that they both contribute to the switch cost (including its residual component). Although attentional inertia reduced with preparation, both handicaps were present at the longest preparation intervals. The constancy of the delay in attending to the relevant attribute reflects the effort to re-allocate attention, rather than peculiarities of spatial orienting when the cue and stimulus are presented near-simultaneously on trials with short cue-stimulus intervals. The presence of attentional inertia in blocks with long preparation intervals suggested some component of inertia immune to preparation (though see Experiments 5 and 6 below). Experiments 3 and 4 investigated the extent to which attentional selection can be decoupled from other task-set components. Cues which explicitly provided location information reduced (or eliminated) the attentional effects found in Experiment 2 indicating that attentional selection can be decoupled from other task-set components. However, Experiment 3 found that the ‘natural’ state is for attentional selection to be coupled at least to a degree (and accessed via) task-set. Experiment 5 combined eye-tracking with ERPs to investigate the relative order of attentional selection and reconfiguration of other task-set components. A well-documented ERP marker of task-set preparation always followed onset of the first fixation on the currently relevant stimulus element indicating that (at least some) task-set components are reconfigured in a serial order with spatial selection preceding other components (e.g., loading of S-R rules or other parameters into working memory). Experiments 6 and 7 investigated the nature of attentional inertia. In Experiment 6 participants were given ultimate control over the duration of the preparation interval which eliminated attentional inertia (at least as indexed by preferential fixation of the previously relevant element on switch trials). In Experiment 7 the stimulus comprised three items which were from perceptually distinct classes (digits, letters, objects) to investigate whether the presence of task-specific features would elicit extra attentional inertia and whether early spatial selection was effective enough to block the processing of task-irrelevant features once the stimulus was presented. Although there was some evidence that the previously relevant stimulus element ‘captured’ attention, this tendency was modest in the fixations and absent in performance measures (response congruence effects).
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Liu, Chialun. "Hierarchical control in task switching." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:5dc1f9d4-fbfd-4652-9e1e-bc1b544c7a65.
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Human flexible behaviour is often seen in everyday life tasks. These tasks (e.g., making coffee) are composed of actions (e.g., pouring sugar) that are typically nested within a large task structures made of superordinate components and nested subcomponents. Task switching has been adopted widely as an effective tool to explore the mechanisms of flexible behaviour and can be easily adapted to real-life situations. The core hypothesis explored in this thesis was that there might be another level of control that is responsible for coordinating and scheduling actions in task switching, which I label "meta-control". My first project aimed to establish robust behavioural evidence of meta-control. To test this hypothesis, switching efficiency was treated as a measure of meta-control influence. In a novel design, participants' beliefs about switch probability were manipulated through explicit instruction, allowing manipulation of meta-level control independent of the specific sequence of tasks required. The first three behavioural experiments demonstrated behaviorally that instructions influenced the efficiency of switching even when low-level (bottom-up) experience was matched, and that this effect was motivation-dependent. In follow-up studies, this meta-control influence was found to bias voluntary task selection. Two EEG studies aimed to characterize the level at which instruction affected processing. Motor and task levels were examined with lateralized motor potentials and oscillatory alpha power, respectively. Effects of instruction only existed on alpha power. Overall, the results suggest that expectancy prompts the adoption of distinct control modes across sequences of trials. The second project explored meta-control in a task switching paradigm with a hierarchical task structure in very short (2-4 trial) sequences that were preceded by instructions about switch frequency or switch position. The experiments focused on the benefits and costs of sequence structure, based on the hypothesis that trial sequences are treated as coherent units. Three behavioural studies were conducted for testing this hypothesis. The first utilized instructions about switch frequency to test for sequence transition effects and their influence on switching performance at the trial level. In two subsequent experiments, instructions made explicit the position of a task switch. The results confirmed that instructions about switch position helped participants to build useful sequence representations, and that alternating between sequences influenced trial-level switch processes. Generally, sequence representations have a persisting influence across trials and a pronounced impact at the first trial position of sequences. The experiments in this thesis provide evidence of meta-control in task switching. The first conclusion is that meta-control can be studied with the novel experimental design introduced in this thesis and was found to be reward dependent. The second conclusion is that meta-control acts as a set of parameters that can modulate the mode of control in a sustained way across trials.
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Forrest, Charlotte Louise. "An associative approach to task switching." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3730.
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This thesis explores the behaviour of participants taking an associative approach to a task-cueing paradigm. Task-cueing is usually intended to explore controlled processing of task-sets. But small stimulus sets plausibly afford associative learning via simple and conditional discriminations. In six experiments participants were presented with typical task-cueing trials: a cue (coloured shape) followed by a digit (or in Experiment 5 a symbol) requiring one of two responses. In the standard Tasks condition (Monsell Experiment and Experiments 1-3), the participant was instructed to perform either an odd/even or a high/low task dependent on the cue. The second condition was intended to induce associative learning of cue + stimulus-response mappings. In general, the Tasks condition showed a large switch cost that reduced with preparation time, a small, constant congruency effect and a small perturbation when new stimuli were introduced. By contrast the CSR condition showed a small, reliable switch cost that did not reduce with preparation time, a large congruency effect that changed over time and a large perturbation when new stimuli were introduced. These differences may indicate automatic associative processing in the CSR condition and rule-based classification in the Tasks condition. Furthermore, an associative model based on the APECS learning algorithm (McLaren, 1993) provided an account of the CSR data. Experiment 3 showed that participants were able to deliberately change their approach to the experiment from using CSR instructions to using Tasks instructions, and to some extent vice versa. Experiments 4 & 5 explored the cause of the small switch cost in the CSR condition. Consideration of the aspects of the paradigm that produced the switch cost in the APECS model produced predictions, which were tested against behavioural data. Experiment 4 found that the resulting manipulation made participants more likely to induce task-sets. Experiment 5 used random symbols instead of numbers, removing the underlying task-sets. The results of this experiment broadly agreed with the predictions made using APECS. Chapter 6 considers an initial attempt to create a real-time version of APECS. It also finds that an associative model of a different class (AMAN, Harris & Livesey, 2010) can provide an account of some, but not all, of the phenomena found in the CSR condition. This thesis concludes that performance in the Tasks condition is suggestive of the use of cognitive control processes, whilst associatively based responding is available as a basis for performance in the CSR condition.
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Essig, Fiona. "Cognitive control in verbal task switching." Thesis, University of Hertfordshire, 2015. http://hdl.handle.net/2299/16339.
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Task switching produces a number of reliable behavioural measures, the main focus of interest here being 'switch cost', the increase in response time when switching between tasks as opposed to performing them separately. Switch costs are typically measured between two tasks and compared to a single-task repeat condition. Current explanations of switch cost fall broadly into either active reconfiguration based accounts (e.g. Rogers & Monsell, 1995) whereby the extra time taken to switch between tasks is attributable to reconfiguration of task set, or passive carryover accounts (Allport, Styles & Hsieh, 1994) where extra time is accrued by the need to overcome conflict between the current task set and the enduring activity of the previous task set. This thesis used the Continuous Series II (Gurd, 1995), a novel continuous verbal switching task which requires individuals to switch continuously between increasing numbers of overlearned sequences (e.g. days, numbers). The aim was to investigate the application of general (whole-task) switch costs (RT costs), memory-based switching and the differential pattern of errors produced by the task, with a view to determining the most appropriate theoretical model to explain costs in the task. General switch costs are measured over the whole time course of the task from beginning to end, instead of the more usual measurement of switch cost over a single switch or repeat within the whole task. Such long-term measures of switch cost account for 'global representational structures' in the task, which are said to contribute to the cost of switching yet are absent from local transitional measures (Kleinsorge, Heuer & Schmidtke, 2004). Global representational structures account for not only the current and preceding trials actually performed but also the possible alternatives for the preceding, current and subsequent trials, thereby reflecting all representations relating to performance of the tasks. The Continuous Series II (Gurd, 1995) measures costs continuously over time between increasing numbers of verbal tasks and as yet has not been linked to either a reconfiguration or carryover-based account. Initial administration to healthy controls and neurological patients confirmed difficulty-related increasing costs and revealed a dissociation of errors between two versions of the task, one including semantic categories. This suggested differential sources of control overseeing conflict detection and resolution, linked in this work to Kahneman's dual system model (Kahneman, 2011) and suggesting the implication of active control. Further work with monozygotic twins mirrored for handedness revealed no predicted effect of handedness but did reveal the employment of vocalised inner-speech as a successful self cueing device, known to be supportive of active reconfiguration in switching (Monsell, 2005). Such cueing was employed by this sample of older adults but had not appeared to benefit the neurological patients who clearly had reconfiguration deficits. Further development of the two versions of the task also allowed rejection of a passive carryover explanation of switch-cost on the basis that switching to the easier task was not more difficult, counter to the prediction of Allport, Styles & Hsieh (1994). At this stage it was evident that some portion of general cost for the task may be artefactual, as participants displayed behaviour suggesting the order of tasks and their updating nature (task content) may be inflating cost beyond a pure measure of switching (an inevitable risk of general switch cost measurement). Investigation of task order showed that production of the category 'days' appeared to conflate sources of error. Reducing the difficultly of component tasks (removing the need to update items) demonstrated that a substantial proportion of general cost was indeed purely switch-related. Returning to the question of cueing (previously demonstrated to be beneficial when self-generated), the final study introduced explicit external cues, consistently predicted to benefit switching (Monsell, 2005). These cues did not reduce time costs in verbal task switching and furthermore failed to prevent errors of task order. The lack of external cue benefit supports an amended version of the Rogers & Monsell (1995) task-set reconfiguration model as the best explanation of switch costs in verbal task-switching. This amended model relies entirely on internally generated representations in a closed system and supports the role of active control in generating switch-cost. General cost, while incorporating task-related artefacts, rehearsals and error recovery, nevertheless has at its core a switch related element. Furthermore, the failure of cues to extinguish between-task errors negates excessive reliance on working memory and further supports the rejection of passive carryover accounts of task switch cost.
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Panepinto, Marie. "The Effects of Voluntary versus Forced Task Switching on Task Performance." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-10292009-105633/.
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Research on task switching has focused on the relatively well known task switching cost, usually defined as an increase in RT on a trial directly following a switch. Two main issues with previous studies suggest that their results may not be applicable to real world scenarios; one, that they typically use short and arbitrary tasks in comparison to real work situations and two, that the vast majority force participants to switch rather than allowing them to do so voluntarily, as is common in the workplace. The current experiment utilized two longer lasting tasks (document proofreading and a Sudoku puzzle) to more closely resemble real world sitations and four task switching groups. One group switched voluntarily, one was forced without warning, one was forced with a cue that a switch would be coming, and one served as a no switch control group. Performance, reaction time, and mental workload (NASA-TLX) were measured. Task switch group produced no differential effects on these variables, and no task switching cost was found. Though the hypothesis were not met, these results lend support to the notion that previous lab studies may not adequately resemble real world scenarios and that micromanaging small tasks, and switching between comparatively longer lasting tasks may not be the same thing. More research on this area may help to produce a better understanding of why people task switch and what they experience cognitively when they do so.
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Grange, James A. "Control of cognitive processes in task-switching." Thesis, Bangor University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528334.
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Gilbert, Sam Joseph. "Computational and empirical studies of task switching." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400571.
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Andreadis, Nikolaos. "Task switching in predictable and unpredictable cases." Thesis, University of York, 2010. http://etheses.whiterose.ac.uk/1418/.
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Fourteen experiments have been run in order to provide evidence regarding the cognitive processes that underlie the switching between simple cognitive tasks. Central to these experiments was the predictability factor; in half of the cases, the upcoming task could be predicted in advance with absolute certainty while in the other half no foreknowledge regarding the upcoming task was provided. In all of the experiments, switch costs were found to be smaller when no task foreknowledge was provided relative to when task foreknowledge was available. Chapter 2 provided evidence regarding the interplay of endogenous and exogenous control in task switching. Top-down and bottom-up processes are not completely insulated from one another. Chapter 3 revealed that both task difficulty and task expectancy play a central role in determining performance on unpredictable cases. Based on the results so far, a task switching model was developed and discussed. Chapter 4 concentrated on the effects of task similarity on performance. It seems that in some cases when tasks are similar at a conceptual level then this results to interference increasing switch costs. Finally, on Chapter 5 behavioral and neuroimaging data provided further evidence that expectancy (in the form of trial expectancy) has a central role on task switching performance. In addition, the neuroimaging data revealed brain regions that could be linked with central components of the proposed task switching model. Concluding, in contrast to many task switching approaches, evidence is provided in the thesis in favor of the presence of endogenous control on unpredictable cases. This control, in the form of expectancies regarding the upcoming task or trial, plays a central role on task switching performance.
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Moulden, Drew Jeffrey Andrew. "Physiological mechanisms of task-switching in human subjects." Thesis, University of Ottawa (Canada), 1999. http://hdl.handle.net/10393/8471.
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The nature, and timing, of the cerebral processes that are active when attention is switched between different tasks are not understood. The purpose of this research was to establish electrophysiological evidence for a two-stage, posterior-anterior cerebral processing model for the control of attention switching. Reaction Times (RTs) and Event-Related Potentials (ERPs) were recorded from 22 healthy young adults as attention was cued to switch between two visuomotor tasks. One task ("horizontal") involved determining whether a circle in one of the four boxes of a 2 x 2 grid was in the left or right half of the grid whereas the other task ("vertical") involved determining whether it was in the upper or lower half. Cues designating the appropriate task occurred 200, 1200 or 1500 ms before a target. Cues were either letters (H & V) at the center of ocular fixation, or arrows ( ⇕&⇔ ) at the periphery. The identity of the letters, and spatial location of the arrows, informed subjects what task to perform, what hand to respond with, and whether the task was the same (repeat) or different (switch) from the previous trial. The RT was longer for switch than repeat trials but only during short (200 ms) cue-target intervals. This demonstrates that subjects are able to completely switch attention prior to target stimuli when the cue-target interval was 1200 or 1500 ms. The cues evoked a sequence of potentials that were larger in the switch trials than in the repeat trials: an occipital N200, a parietal P390, and a mid-frontal negative wave with a latency between 400 and 800 ms. The N200 probably represents processing of the stimulus in the extrastriate cortex. The P390 peak was larger for arrow than letter cues at centroparietal electrodes (CP1, CP2), and the inverse was true at temporal-parietal sites (P7, P8). The P390 was also 55 to 59 ms earlier for the dorsal than ventral waveform. This demonstrates that at least two separate neurophysiological events contribute to the amplitude and latency characteristics of the scalp recorded P390. These processes are specific for the physical features of the cues and may correspond to the dorsal "where" and ventral "what" visual streams. Only the mid-frontal negative wave was found to be specifically with the switch in task. This wave may represent activity in the supplementary motor area or anterior cingulate as response rules are changed for the new task. The readiness potential (RP) showed complex relations to switching or repeating the task. In general, this potential was larger over the hemisphere contralateral to the hand that was being prepared for response. When there was some urgency in the task, the readiness potential was bilateral on switch trials, perhaps because the previous hand was automatically activated in case it might be needed. Left and right lateral pre-frontal slow waves occurred throughout each trial. These may represent task monitoring and/or working memory processes. These results suggest that both posterior and anterior brain regions participate in attention switching. Posterior ERPs seem to be associated with identifying the physical features of stimuli that signal the need to switch attention between tasks, whereas the mid-frontal negativity appears to be related to carrying out the switch once the need to switch has been identified. The RP indicates the preparation of a hand for response. The strategy of this preparation varies with the urgency of the switch. Other anterior processes may monitor task performance.
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Moulden, Drew J. A. "Physiological mechanisms of task-switching in human subjects." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0016/NQ46536.pdf.
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Yang, Violet Hye-Won. "The role of inhibitory control in task switching." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/14156/.
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Previous research on task switching has been confounded by inhibitory control mechanism and there has been debate on the source of switch costs and how and when the inhibitory control occurs during task switching. In order to circumvent this problem, the thesis aimed to investigate the role of inhibition in task switching by examining switch costs, alternating switch costs and congruency effect in three tasks when two preparation intervals (short and long) are given. Task switching experiments in the present study captured both flexibility (changes in task) and anticipatory control (preparation interval between cue and target) and provided the measurement for inhibitory control, 'backward inhibition' by alternating switch cost. Backward inhibition was manifest in longer reaction times (and/or more errors) to alternating switch trials (ABA) than to double switch trials (CBA). Reaction time and error in the present study also reflected whether the task in the current trials were easy when it requires the same response as the task in the previous trials, i.e., whether the required response were congruent. The results in the thesis provided the strong evidence for switch costs as one of cognitive control mechanism and it was reduced by the long preparation interval through all the experiments. When the cues were arbitrarily matched for each task, switch costs were increased, suggesting that high working memory load and the effort for interpretation of the cues might cause more additional process during switching tasks. On the other hand, the change of the cue type was insensitive to backward inhibition since there were no significant differences on the size of alternating switch costs. The results imply that the occurrence of backward inhibition is more prone to the type of task you perform and level of congruency.
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Morcom, Alexandra. "The role of executive control in task switching." Thesis, University of Bristol, 2000. http://hdl.handle.net/1983/d1108d24-de51-45e7-b3fe-49bdde78bacf.
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This thesis addressed the question of whether global, 'executive' control processes are involved in switching between discrete cognitive tasks. The involvement of executive working memory processes in the control of switching was examined, using a combination of cognitive and cognitive neuropsychological methods. In all studies, participants switched unpredictably between two simple tasks, and in some cases they also performed concurrent tasks. The focus throughout was on two putative areas of executive control that may influence task switching, goal-directed advance processing, and the suppression of interference between tasks. The first series of experiments explored whether the central executive of working memory is required to prepare for a task switch, but found no evidence that this is the case, whether an endogenous or an exogenous method of task cueing is used. The possibility was then raised that cognitive control does not just operate when the task switches, and a further study showed that this is, indeed, the case. However, two experiments using different task cueing methods did not reveal any evidence that executive processes in working memory carry out this control. It did, however, appear that the central executive is required for overall task performance, as opposed to task switching, when the method of cueing requires that participants keep track of and update information about which task is to be performed. The final study examined task switching and executive function in a group of patients with damage to the frontal lobes, and to posterior areas of the brain. Although a number of participants showed evidence of executive deficits, they had no difficulty in switching in a speeded response task. In conclusion, it is argued that local, rather than global, control processes are involved in switching tasks in the present paradigm, and implications are discussed for theories and investigation of executive control. 2
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LaGrone, Susan Rebecca. "Testing the Interaction of Stimulus Repetition with Switch Costs Across Age Groups." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16223.
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Task-switching studies are a popular measure of executive control, yet the influence of stimulus repetition in these studies is less well recognized. One theory from the literature states that stimuli associated with a certain response interfere with processing of those same stimuli in another task, contributing to task switching costs (Waszak, Hommel, &Allport, 2003). The current study varied stimulus repetition in younger and older adults and found that the previous task associated with a stimulus does influence overall performance but did not find the expected interaction of switch and repetition conditions. Results of this study extend our information about the role of stimulus repetition in task-switching studies as well as how this repetition relates to age differences in switch costs.
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Walker, Darren James. "Remembrance of things future : involuntary and strategic processes in prospective memory reminders." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272232.
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Perkins, Matthew. "Differential dynamics of network states| implications for task switching." Thesis, Icahn School of Medicine at Mount Sinai, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10099545.
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A change in a stimulus response relationship implies that there has been a change in the internal state of the relevant behavior-generating network. Frequently, network states are persistent, biasing responses for some time following stimulus exposure. This benefits subsequent behavioral performance when the same stimulus is re-encountered. Alternatively, it can also negatively impact initiation of a second (distinct) task, i.e. there can be a task-switch cost. Recently, work from a few invertebrate model systems has begun to determine how experience dependent network states are mediated on a cellular/molecular level. A fundamental question I have addressed is, does the establishment of one network-state remove a prior state, or can two network states overlap and interact? In this thesis I provide data that indicate that in the feeding circuit of Aplysia, network states that promote incompatible behaviors can indeed overlap. In addition, I describe a novel role for a cyclic nucleotide gated ion-current, as supporting an experience dependent network state through a persistent modulation of cell excitability.
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Wasylyshyn, Christina V. "Individual differences in task switching, executive functioning, and cognition." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2007. http://wwwlib.umi.com/cr/syr/main.
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Slama, Hichem. "Task-goal switching: Influences of time, language, alertness and expertise." Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/229285.
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Almost 100 years ago, Jersild (1927) published his article “Mental Set and Shift”. He borrowed this title from a book of Hollingworth and Poffenberger (1919), according to whom “shifting back and forth from one mental set, one attitude or one task to another, is a relatively ineffective mode of work.” As pointed out by Jersild, the cost of switching between activities or mental sets is, for instance, the reason for Taylor’s model of industrialization and the trend in industry toward specialization. Through specialization, the element of switch is reduced to its minimum because “the cost of shift is loss in efficiency” (Jersild, 1927). However, outside of the factory, switching between multiple tasks is a crucial part of human life and the cost of switching, consequently, impacts our everyday functioning.The main topic of this doctoral dissertation is cognitive flexibility and task switching. The task-switching paradigm requires participants to switch frequently between tasks. Therefore, it measures the capacity of our brain to adapt rapidly according to tasks and goals. Dynamic adaptation according to context and goals is encompassed in cognitive psychology and neurosciences under the term cognitive control. Consequently, the ability to switch between tasks constitutes the part of cognitive control that is needed when the current goal changes and the cognitive system has to adapt. Our experimental contribution aimed at investigating how this task-goal switching can be modulated by factors such as time, language, alertness and expertise. In this introduction, we succinctly review the vast literature about attentional systems, cognitive control and task switching. In the experimental section, we describe the cued match-to-sample task that we developed to investigate task-goal switching and present five experimental studies that address the impact of several factors on task-goal switching. In the general discussion, we summarize our results and consider their implications for cognitive-control and task-switching literatures.Doctorat en Sciences psychologiques et de l'éducation
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Schultz, Eric A. "Empirical Performance Comparison of Hardware and Software Task Context Switching." Thesis, Monterey, California. Naval Postgraduate School, 2009. http://hdl.handle.net/10945/46226.
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Approved for public release; distribution unlimited.There are many divergent opinions regarding possible differences between the performance of hardware and software context switching implementations. However, there are no concrete empirical measures of their true differences. Using an empirical testing methodology, this research performed seven experiments, collecting quantitative performance results on hardware and software-based context switch implementations with two and four hardware privilege level support. The implementations measured are the hardware-based Intel IA-32 context switch, the software-based MINIX 3 context switch, a software-based simulation of a MINIX 3 context switch with four hardware privileged level support, and a software-based simulation of an Intel IA-32 hardware context switch. Experiments were executed using the Trusted Computing Exemplar Least Privilege Separation Kernel and the Linux 2.6 Kernel. The results include the number of cycles and time required to complete processing of each implementation. This study concludes that the hardware-based context switching mechanism is significantly slower than software implementation, even those that simulate the elaborate checks of the hardware implementation. A possible reason for this is posited.
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Prosser, Laura. "The backward inhibition effect in task switching : influences and triggers." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=237859.
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It has been proposed that backward inhibition (BI) is a mechanism which facilitates task-switching by suppressing the previous task. One view is that BI is generated in response to conflict between tasks being experienced during task-performance. Across twelve experiments, this thesis investigated this proposition by addressing two questions: What affects the size/presence of BI? and When is BI triggered?: What affects the size/presence of BI? and When is BI triggered? The findings from Chapter 2 suggest that BI is increased when conflict stemming from shared target features is present, and that the expectation, as well as experience, of conflict might increase BI. Chapter 3 suggests that BI is increased when target features are shared (and that no BI is present otherwise), but contrary to previous findings, BI is not increased when response features are shared. Chapter 4 provided indirect support for the view that BI can be present without between-task conflict (i.e., neither shared targets nor responses), and indicated that in such a context BI (at least at item-level) requires trial-by-trial cuing. Chapter 5 indicates that BI is triggered prior to response execution and after the preparation stage of task processing, therefore indicating that either the target processing stage or the response selection stage of task processing are responsible for triggering BI. Together, the results of the experiments in this thesis indicate that BI can be driven by conflict stemming from target sharing. However, there was no evidence that conflict stemming from response sharing drives BI. In addition, the data suggested that BI might be generated by the expectation of conflict and by task preparation. Therefore, BI might be applied in response to conflict at any stage of task processing and the decision to apply BI might be decided in advance of such conflict.
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Gul, Amar. "Practice, stimulus-specific effects and individual differences in task switching." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3658/.
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This thesis points to the important roles of learning, individual differences in emotional intelligence (EI) and general intelligence (IQ), and culture (British vs. South Asian), on task switching. Participants switched between word identities and colour and between different face dimensions (emotion, gender and occupation). In general switch costs were reduced as participants practiced. Most interestingly, Stroop interference across blocks of trials was stronger for stimuli that form integrated representations, providing evidence that learned bindings between word forms and colours influence Stroop effects. In a separate study, people with high IQ were generally better able to task-switch while EI had a selective effect depending on the task. Individuals with high EI had low switch costs when emotion classification was involved, but not when switches were made between gender and occupation decisions. In a third set of studies, culture was found to affect the speed of face categorization, which may reflect cultural biases to emotion (in the White British population) and unfamiliarity in using facial cues to gender in South Asian participants. Finally, there was also evidence of implicit coding of facial emotion and gender - but not occupation. The implications for understanding task switching were reviewed in a final chapter.
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Park, Joonsuk Park. "HORTAS: A Horserace Model of Cognitive Control in Task Switching." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471864081.
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van't, Wout Felice Maria. "Task-set control and procedural working memory." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3750.
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Flexible and goal-driven behaviour requires a process by which the appropriate task-set is selected and maintained in a privileged state of activation. This process can be conceptualised as loading a task-set into a procedural working memory (PWM) buffer. Task switching experiments, which exercise this process, reveal “switch costs”: increased reaction times and error rates when the task changes, compared to when it repeats. The process of loading a task-set into PWM may be one source of these costs. The switch cost is reduced with preparation, suggesting that at least some of the processes involved in a successful change of task can be achieved in advance of the stimulus. The aim of this thesis was to investigate the properties of PWM, and its contribution to task-set control. One account of PWM distinguishes between the level at which recently exercised (but currently irrelevant) task-sets are represented, and the level at which only the currently relevant task-set is maintained in a most active state. To distinguish between these levels of representation, and to assess the extent to which the process of getting a task-set into a most-active state (loading it into the PWM buffer) is subject to a capacity limit at each level, the experiments varied the number of tasks participants switched among (Experiments 1 and 2), and the complexity of individual task-sets (Experiments 3-6) in a task-cueing paradigm. In Experiments 1 and 2, participants switched among three or five tasks, in separate sessions. There was no effect of the number of tasks on the switch cost, or its reduction with preparation, provided that recency and frequency of task usage were matched. When recency and frequency were not matched, there appeared to be a larger switch cost with five tasks at a short preparation interval, suggesting that the time consumed by getting a task-set into a most active state is influenced by its recency and frequency of usage, not the number of alternatives per se. However, Experiment 3 showed that the time required to select an S-R mapping within a task-set does increase as a function of the number of alternatives (even when stimulus frequency and recency are matched), suggesting that representation of the most active task-set in a PWM buffer is subject to a strict capacity limit. Experiments 4-6 further investigated the capacity limit of this PWM buffer, and found that task-set preparation was more effective for task-sets that are less complex (i.e. specified by fewer S-R rules). These findings suggest that only very few S-R rules can be maintained in a most active state in the PWM buffer. Finally, Experiments 7-9 investigated whether S-R rules are represented phonologically for task-set maintenance and preparation, by manipulating the phonological properties of the stimulus terms. But task-cueing performance was not affected by the name length (Experiment 7) or phonological similarity (Experiments 8 and 9) of the stimulus terms. These results suggest that phonological representations of S-R rules do not make a functional contribution to task-set control, possibly because the rules are compiled into a non-linguistic PWM. The results of these experiments are discussed in terms of a procedural working memory which is separate from declarative working memory, and distinguishes between two levels of task-set control: the level of task-sets, which are maintained in a capacity unlimited state of representation, and the level at which the currently relevant task-set is maintained in a most-active but highly capacity limited state of representation.
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Grabbe, Jeremy W. "Cross-task Compatibility and Aging." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1201548686.
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Forstmann, Birte U. "Behavioral and neural correlates of endogenous control processes in task switching /." Leipzig [u.a.] : MPI for Human Cognitive and Brain Sciences, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014846005&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Kowalczyk, Agnieszka Wioleta. "Cognitive inhibition in task switching : exploring the n-2 repetition cost." Thesis, Keele University, 2018. http://eprints.keele.ac.uk/5600/.
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The current thesis provides novel insights into the n–2 repetition cost, a task-switching behavioural effect thought to reflect cognitive inhibition. The n–2 repetition cost is widely used as a measure of group and individual differences in inhibitory control; however, there was uncertainty around its reliability and the extent to which it reflects cognitive inhibition. Overall, the current thesis indicates that the n–2 repetition cost is unlikely to be a measure of cognitive inhibition. Experiment 1 showed that the n–2 repetition cost has low reliability at an individual level, which questions its use as a measure of individual differences in inhibitory control. Experiments 2–4 demonstrated that the n–2 repetition cost is considerably modulated by a non-inhibitory mechanism (i.e., episodic retrieval), which means that the common understanding that the cost reflects cognitive inhibition is incomplete. Furthermore, Experiments 5–7 show that the n–2 repetition cost seems not affected by cognitive resources as it is not modulated by working memory load; however, from Experiments 8–9 it cannot be said for certain that the cost is not modulated by attentional resources, because a trend for the cost to be smaller under conditions exhausting attentional resources was present. In terms of the individual differences in the n–2 repetition cost, this thesis shows that they are not explained with processing speed, depressive rumination, working memory capacity, or day-to-day distractibility trait (Experiments 1, 4, 7, 8–9). And, computational modelling analyses (ex-Gaussian and diffusion modelling; Simulation Studies 1–4) support the view that the n–2 repetition cost is mainly due to non-inhibitory mechanisms. Taken together, the current thesis indicates that the n–2 repetition cost is unlikely to reflect cognitive inhibition, and if used as such should be interpreted with caution.
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Sylvan, Elisabeth 1973. "Dealing with distractions : analyzing and designing for task switching at work." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/88356.
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Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2003.Includes bibliographical references (p. 78-81).
Elisabeth Sylvan.
S.M.
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McCully, Scout N. "Task-Switching, Flexible Self-Regulation, and Physical Activity in Young Adults." Kent State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1402408598.
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Stevens, Tobias. "Cortical regions involved in proactive control of task-set." Thesis, University of Exeter, 2011. http://hdl.handle.net/10036/3285.
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This thesis is about what happens in the brain when people switch between tasks. Each task requires a particular assembly of cognitive processes, an orientation of attention and set of rules relating action to input — a "task-set". The research reported used a task-cueing paradigm to study preparatory control of task-set. On each trial a stimulus (a coloured shape) was preceded by a verbal task-cue specifying which task to do (judge the shape or the colour of the stimulus). Reaction time and error rate increase on trials when the task changes relative to trials on which it does not. When the cue stimulus interval (CSI) is increased, this "switch cost" is reduced, indexing a process of task-set reconfiguration in which top-down control is employed to reconfigure the task-set parameters. Effective reconfiguration may also be indicated by a reduction in the "response congruence effect" — poorer performance on stimuli mapped to different responses for the two tasks than for stimuli mapped to the same response. I present six experiments using transcranial magnetic stimulation (TMS), a technique for interfering briefly and harmlessly with neuronal activity in a small region of cortex, to address the question of which brain regions contribute to anticipatory control of task-set as indexed by these behavioural measures. To help guide the selection of candidate brain regions, I first present a review and meta-analysis of neuroimaging studies of task-switching in the literature. Many fMRI studies, comparing brain activation on task-switch and -repeat trials have been published. Some have also tried to isolate activations related specifically to pro-active control of task-set. The activations reported are quite inconsistent over studies. I used a quantitative meta-analysis technique to identify which brain regions are most consistently found by studies reporting switch minus repeat contrasts and which may be specifically important for preparation on switch trials. The experiments examined the effect of stimulating several regions during the long cue-stimulus interval of a task-cueing paradigm, relative to control conditions. A first pair of experiments suggests an important role in proactive task-set control for two regions in dorsal medial frontal cortex, the supplementary motor area (SMA) and an area known as pre-SMA, though the former region appeared to contribute to reducing the switch cost while the latter appeared to reduce the effects of response congruence. In a further three experiments, I examined the role of the right intra-parietal sulcus (rIPS); this appears to play a crucial role in preparation for a task-switch but not post-stimulus task-set reconfiguration. In a final experiment, I used TMS guided by fMRI activations in the same participants to study the effects of stimulation over the left inferior frontal junction (IFJ). The results indicate that a region just anterior to the left IFJ is specifically important for preparing for a switch trial. I discuss the roles that may be played by these three regions in task-set control.
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Breeze, Julian. "Task switching and cognitive control processes : measured using increases to stimulus dimension, stimulus set size and task practice." Thesis, Bangor University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494186.
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The aim of this thesis is to understand some of the processes involved in the selection of appropriate tasks, and in the selection of correct responses to those tasks. The main focus of the following experiments will be on how interference and conflict occurs during these processes, either at the perceptual or action selection stages when switching task. It should be possible to demonstrate with increases to the number of attributes, the experience of tasks associated with non-target attributes, and in varying the number of trials before switching tasks, that task selection consists of several stages or processes, and that these processes do not necessarily interact. This will show that the switch cost is not an unitary cost associated with changing a single response-stimulus setting, task parameter, or an overall task set, but a composite of various costs associated with different task selection processes.
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Coates, Mark A. "Event Related Potential Measures of Task Switching in the Implicit Association Test." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19917.
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Since its creation in 1998, the Implicit Association Test (IAT) has become a commonly used measure in social psychology and related fields of research. Studies of the cognitive processes involved in the IAT are necessary to establish the validity of this measure and to suggest further refinements to its use and interpretation. The current thesis used ERPs to study cognitive processes associated with the IAT. The first experiment found significant differences in P300 amplitude in the Congruent and Incongruent conditions, which were interpreted as a reflection of greater equivocation in the Incongruent condition. The second experiment tested the task-set switching account of the IAT in much greater detail by analyzing each trial type separately. In the Congruent condition, all trial types elicited the same amplitude P300. Local probability, and the consequent checking and updating of working memory, was thought to be responsible for differences between trials of the Incongruent condition that required or did not require a task switch. The final experiment examined the role of working memory in the IAT by introducing obtrusive and irrelevant auditory stimuli. The results of Experiment 3 indicated that the introduction of an obtrusive and irrelevant auditory increment deviant has little overall effect on the IAT, and a similar effect on switch and no-switch trials within the Incongruent condition. This could have been because both the Congruent and Incongruent conditions of the IAT make such extensive demands on central processing resources that few are available to allow for the switching of attention, or it is possible that the IAT does not require significant updating of working memory. The usefulness of ERPs in the study of the IAT effect is demonstrated by the current research. In particular, the finding that behavioural results were not always consistent with the ERP results demonstrates that electrophysiological measures can complement traditional behavioural measures.
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Yeung, Nicholas Peter. "Switching between simple cognitive tasks : interactions between executive control and task properties." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621559.
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Elchlepp, Heike. "The temporal dynamics of switching tasks." Thesis, University of Exeter, 2011. http://hdl.handle.net/10036/3233.
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The topic of this thesis is cognitive control: how the brain organises itself to perform the many tasks it is capable of and how it switches flexibly among them. Task-switching experiments reveal a substantial cost in reaction time and accuracy after a switch in tasks. This "switch cost" is reduced by preparation (suggesting anticipatory task-set reconfiguration), but not eliminated. The thesis focuses on the sources of the "residual" cost. Most accounts attribute it to response selection being prolonged on a task-switch trial by task conflict, e.g. by 'task-set inertia' — persisting activation/inhibition of the previous task's S-R rules — or their associative reactivation by the stimulus. Four experiments used event-related potentials (ERPs) to determine which stages of task processing are influenced by a change in tasks, looking for delays in process-specific markers in the ERP. Experiments 1 and 2 showed that a prepared switch to a reading task from a perceptual judgement delayed early ERP markers of lexical access by a large fraction of the RT switch cost, suggesting that a substantial part of the residual cost arises in processes earlier than response selection, possibly due to task-related attentional inertia. Markers of lexical access observed in the non-lexical task were larger on switch than repeat trials, providing the first electrophysiological evidence of task-set inertia. Experiment 3 examined the effects of an unprepared switch in the same way. ERP waveforms were modulated by a switch before markers of lexical access were evident, suggesting additional processing demands compete for resources with lexical access. A simple delay, however, was not found; post-stimulus task-set reconfiguration does not just insert an extra processing stage. Experiment 4 looked for a delay in the onset of an early ERP marker of emotional processing when the task switched between categorising facial expression and classifying a superimposed letter. No such delay was found in this case, and ERP markers of emotion processing were present to the same extent in the letter task. This suggests that, given appropriate spatial attention, processing facial emotion unfolds automatically, independent of attention allocation to the facial features. Experiments 5-7 further explored the link between conflict due to processing the irrelevant stimulus dimension and the ERP post-stimulus negativity that accompanies the residual cost. The negativity could be elicited even on trials of non-switching blocks by prior training on classifying the irrelevant attribute of the stimulus using the same responses. But this effect did not seem to result from the trained class of irrelevant attribute attracting more attention. Finally, Experiment 8 followed up an incidental observation in Experiment 1 to establish the novel observation that a task-switching context abolishes the usual ERP correlate of withholding a response in a go/no-go paradigm, suggesting an interesting interaction between task-set control and response inhibition.
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Kehagia, Angeliki. "Frontostriatal components of executive control in task set switching and rule-based behaviour." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612018.
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Seibold, Julia Christine [Verfasser], Iring [Akademischer Betreuer] Koch, and Miriam [Akademischer Betreuer] Gade. "Examining independently switching components of auditory task sets : towards a general mechanism of multicomponent switching / Julia Christine Seibold ; Iring Koch, Miriam Gade." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1196018324/34.
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Zhou, Elayne. "Does What You Do Before Class Matter?" Oberlin College Honors Theses / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1528222715870267.
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Johnson, C. Dustin. "Set-Switching and Learning Transfer." Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/psych_hontheses/7.
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In this experiment I investigated the relationship between set-switching and transfer learning, both of which presumably invoke executive functioning (EF), which may in turn be correlated with intelligence. Set-switching was measured by a computerized version of the Wisconsin Card Sort Task. Another computer task was written to measure learning-transfer ability. The data indicate little correlation between the ability to transfer learning and the capacity for set-switching. That is, these abilities may draw from independent cognitive mechanisms. The major difference may be requirement to utilize previous learning in a new way in the learning-transfer task.
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Sexton, Nicholas J. "Human task switching and the role of inhibitory processes : a computational modelling and empirical approach." Thesis, Birkbeck (University of London), 2018. http://bbktheses.da.ulcc.ac.uk/356/.
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Task switching is a behavioural paradigm within cognitive psychology that has been claimed to reflect the activity of high-level cognitive control processes. However, classic behavioural markers such as the (n-1) switch cost have also been shown to reflect a multitude of other cognitive processes. The n-2 repetition paradigm has proven more successful, with a behavioural measure (the n-2 repetition cost) agreed to be reflective of a cognitive inhibition mechanism (‘backward inhibition’). The present thesis develops computational models of task switching, including a backward inhibition model. The models are developed within the interactive-activation and competition (IAC) framework, as a development of an existing task switching model. Modelling is constrained by the general computational principles of the IAC framework and default parameter settings where these are shared with earlier models. The effect of specific novel parameter settings on behaviour is explored systematically. The backward inhibition model predicts a range of empirically observed behavioural phenomena including both n-1 switch and n-2 repetition costs, and the modulation of the n-2 repetition cost under certain circumstances, including the manipulation of intertrial intervals. A specific prediction of the model, the modulation of n-2 repetition costs according to switch direction when tasks are of different difficulties, is tested empirically, with results confirming and providing validation of the model. Finally, consideration is given to how such a backward inhibition model could be adapted to maximise performance benefits in different task switching contexts, via a process of parameter tuning.
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O'Leary, Allison. "Voluntary Task Switching in Children and Adults: Individual Differences in the Facilitative Effect of Choice." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1398866891.
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Fintor, Edina [Verfasser], Iring [Akademischer Betreuer] Koch, and Andrea [Akademischer Betreuer] Kiesel. "New insights into modality-compatibility effects in task switching / Edina Fintor ; Iring Koch, Andrea Kiesel." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1210929058/34.
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Fintor, Edina Verfasser], Iring [Akademischer Betreuer] [Koch, and Andrea [Akademischer Betreuer] Kiesel. "New insights into modality-compatibility effects in task switching / Edina Fintor ; Iring Koch, Andrea Kiesel." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1210929058/34.
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Dussias, Paola Eulalia 1962. "Switching at no cost: Exploring Spanish-English codeswitching using the response-contingent sentence matching task." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282384.
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The Functional Head Constraint (Belazi, Rubin and Toribio, 1994) states that codeswitching is not allowed between a functional head and its complement. This predicts that switches between determiners and noun phrase complements, complementizers and inflected clausal (IP) complements, and auxiliaries and verb phrase complements should be ungrammatical. Conversely, the proposed constraint predicts that verb-complement and preposition-complement switches should be grammatical. This study tested four of these five predictions, using codeswitched Spanish/English sentences which met or violated the Functional Head Constraint. The subjects were Spanish-English bilinguals who had learned both languages before the age of six and who use both languages in their daily lives. Data were collected using the Response-Contingent Matching Task (Stevenson, 1992). Subjects read a sentence displayed on a computer screen and press a button when the reading is completed. They then read a second sentence aligned below the first one and press one of two buttons to indicate whether the two sentences on the screen are the SAME or DIFFERENT. Grammaticality of the codeswitch was established by comparing reading times on all SAME sentences. The sentences that violated the Functional Head Constraint were expected to receive significantly longer reading times than the sentences which comply with the constraint. The results obtained do not support the predictions made by the Functional Head Constraint, but do confirm the validity of the task procedure. The findings are compared with naturalistic data and are interpreted using the Minimalist Theory of Chomsky (1991 and 1992).
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Hubbard, Jason. "The Dynamics of Global States in Executive Control." Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22632.
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In the present work, we examine how the cognitive system responds to complex environments. It has been proposed that executive control, which is responsible for orchestrating high-level behavior in such environments, operates according to different broad processing modes, one geared towards stability and focus (“maintenance”), and the other that’s open to environmental influence (“updating”). Aging work has proposed that this latter mode is over-represented in older age, leading to deficits in many, but not all cognitive domains. Across three studies, we sought to identify the dynamics of the updating state in particular, and how those dynamics are shifted in older age. In Chapter 2, we used a paradigm designed specifically to enforce maintenance and updating states with an age-comparative sample, and found that older adults show increased behavioral costs (reaction times) and distractibility (distractor fixations) consistent with being “chronic updaters”. In Chapter 3 we probed the updating state by examining spontaneous fixations towards irrelevant cues, allowing us to identify how it occurs both in response to the task context, and independently from it. We found that older adults were more sensitive to global changes in the task context (single versus mixed-task blocks), but also showed a stronger tendency to update independently from the task. Younger adults, by contrast, were more prone to update in response to transient task events. In Chapter 4, we lay the groundwork to address these questions with neuroimaging, using machine learning to extract information regarding the task context (task set, targets, distractors, response-selection) in a task-switching paradigm on a trial-by-trial and moment-by-moment level. This opens the door for more directly measuring neural signatures of updating and gives a more high-fidelity measure to examine the dynamics of how and when it occurs. Together, this work provides some insight into the dynamics and age-differences involved in global processing states, which heretofore have been under-investigated in the literature. Additionally, we provide important analytic and methodological advancements for extending this work in the future.
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Meier, Christina. "A comparative investigation of associative processes in executive-control paradigms." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/26798.
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The experiments reported in this thesis were conducted to examine the effects of executive-control and associative-learning processes on performance in conventional executive-control paradigms. For this purpose, I developed comparative task-switching and response-inhibition paradigms, which were used to assess the performance of pigeons, whose behaviour is presumably based purely on associative processes, and of humans, whose behaviour may be guided by executive control and by associative processes. Pigeons were able to perform accurately in the comparative paradigms; hence, associative-learning processes are sufficient to account for successful performance. However, some task-specific effects that can be attributed to executive-control processes, and which were found in humans applying executive control, were absent or greatly reduced in pigeons. Those effects either reflect the mental operations that are performed to ensure that a specific set of stimulus-response-contingencies is applied and any contingencies belonging to a different set are suppressed, or reflect mental preparations for the possibility that the requirement to execute a certain response suddenly changes. In particular, in Chapter 3, it is shown that the benefits of repeatedly applying the same set of stimulus-response contingencies (or, in reverse, the costs of switching from one set to another) do not apply when Pavlovian processes dominate learning, which is likely the case for pigeons. Furthermore, as shown in Chapters 4 and 5, the behavioural effects of preparing for an unpredicted change in response requirements appeared to be absent when behaviour was based purely on associative processes. Instead, associatively mediated performance was primarily influenced by the stimulus-response contingencies that were effective in each paradigm. Repeating the same response in consecutive trials facilitated the performance of pigeons and associatively learning human participants in the task-switching paradigms, and performing a particular Go response increased the pigeons' likelihood of executing that response in the following trial in two response-inhibition paradigms. In summary, any behavioural effects that can be observed at the level of abstract task requirements reflect the influence of executive-control processes, both in task-switching paradigms and in response-inhibition paradigms.
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Chaplin, Caley. "The factors affecting self-regulation through the analysis of physiological, psychological and behavioural measures during task-switching." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1006027.
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Individuals are required to manage multiple tasks which require strategic allocation of time and effort to ensure goals are reached efficiently. By providing the worker with autonomy over their work, performance and worker well-being have improved. This increased control allows individuals to organize work according to the needs of the body, which prevents fatigue leading to improved productivity. When given the option, humans tend to switch between tasks frequently. This behaviour can be used to determine the change in self-regulation strategies. An understanding of human task-switching behaviour is important for the design of job rotation systems. However, there is a lack of evidence explaining the factors motivating the need to switch between tasks. This study aims to use physiological, subjective and behavioural measures to explain the factors influencing selfregulation through the act of task-switching. Three primary hypotheses were developed to explain the factors underlying taskswitching behaviour. It was hypothesized that the degree of boredom experienced, the effort required to perform the task and the resource usage induced by the task are factors responsible in deciding task switching behaviour. Participants (17 males and 17 females) switched freely between five different information-processing tasks for the 45 minutes. Participants were allowed to switch back and forth between tasks and did not have to conduct all five tasks. The following measures were recorded during the experiment: subjective measures of boredom, mental effort, task frustration and perceived performance of the tasks; energy consumption and physiological measures of effort (HR, HRV and body temperature) and behavioural measures, including duration and frequency of task. Perceived boredom was found to differ among the tasks and before and after the experiment. The average boredom rating at each task transition for all tasks exceeded a score of 2.5 out of a possible 4. There were no significant changes in physiological measures between the beginning and end of the task trials. However, changes in physiological measures showed a decrease in effort investment following task transition. Heart rate variability was lower for externally-paced tasks than for self-paced tasks, despite the differences in cognitive demands. The most frequent task-switch combination occurred between tasks of high and low cognitive demand. The least frequent task-switching combination occurred between tasks of similar characteristics, which produced no differences in physiological responses. Task-switching behaviour was influenced by the degree of boredom, and therefore more time was spent on less monotonous tasks. The level of physiological effort required for the task affected task-switching behaviour. Task switches were made before any changes in effort took place in an attempt to maintain task efficiency. It appears plausible that a task switch was made to reduce effort investment and activation levels. The type of information processing resources used by different tasks affected the task-switching combinations. Individuals tended to switch between tasks of differing resources so that those in limited supply were able to replenish. Therefore the findings from this study can potentially be used to improve the design of job rotation systems. Such improvements may enhance productivity and worker well-being by inhibiting the onset of down regulation and fatigue processes. This study showed that autonomy is necessary for individuals to regulate behaviour to suit human needs.Microsoft� Office Word 2007
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Bryck, Richard Lee 1978. "Flexible behavior under control? Neural and behavioral evidence in favor of a two-component model of task-switching." Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/7488.
Full textAbstract:
xiii, 163 p. : ill. (some col.) A print copy of this title is available through the UO Libraries under the call number: KNIGHT QP360.5 .B79 2008The ability to rapidly change from one course of action to another, i.e. "flexible behavior", is a hallmark of human cognition. Laboratory observations of switch costs, an increase in reaction time and errors when alternating between tasks compared to repeating a task, have been argued to be a measure of endogenous control during flexible behavior. However, alternative models suggest no such reconfiguration processes are necessary to account for performance in these task-switching situations. The first part of this dissertation uses neuroimaging to address whether reconfiguration processes do in fact occur in the explicit cuing variant of the task-switching paradigm. Using a 4:2 mapping between cues and tasks, we found neuroanatomical evidence for a dissociation between cue-switch (left prefrontal and lateral parietal) and task-switch (medial precuneus and cerebellar) related areas, consistent with the claim of endogenous control during task selection. The second portion explores whether automatic, long-term memory (LTM) processes can explain the "switch cost asymmetry", the fact that switch costs are larger when switching into a dominant task rather than into a competing non-dominant task. We modified an alternating runs task-switching paradigm to include either long or short response-to-stimulus intervals (RSIs) after each pair of trials (i.e., AA-AA-BB-BB), thereby inducing selection costs not only at the point of a task-switch (i.e., AA-BB), but also between same-task pairs (i.e., AA-AA). Using spatially compatible versus incompatible response rules and Stroop word versus color naming, we found asymmetric effects not only at task-change transitions, but also at task-repeat transitions when the RSI was long (presumably inducing frequent losses of task set). In two additional experiments, an asymmetry for long RSIs was obtained even when competing tasks were separated into alternating single task blocks, but not when the tasks were compared in a between-subject design. This pattern supports the idea that the asymmetry arises from interference effects occurring in LTM traces. The combined results of this dissertation characterize task-switching processes not as an "either-or" phenomenon in regards to the question of control, but rather as the interplay between top-down, executive functions and bottom-up, long-term memory priming mechanisms.
Adviser: Ulrich Mayr
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Ard, Michael Colin. "On the origin of a response time underadditivity by means of cross-modal task switching, or the redundancy of operations in the configuration of task sets for cross-modal shifts." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3366481.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed August 20, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 178-184).