Dissertations / Theses on the topic 'Visual discrimination'
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1
Weikum, Whitney Marie. "Visual language discrimination." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/481.
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Recognizing and learning one’s native language requires knowledge of the phonetic and rhythmical characteristics of the language. Few studies address the rich source of language information available in a speaker’s face. Solely visual speech permits language discrimination in adults (Soto-Faraco et al., 2007). This thesis tested infants and adults on their ability to use only information available in a speaker’s face to discriminate rhythmically dissimilar languages.
Monolingual English infants discriminated French and English using only visual speech at 4 and 6 months old, but failed this task at 8 months old. To test the role of language experience, bilingual (English/French) 6 and 8-month-old infants were tested and successfully discriminated the languages. An optimal period for sensitivity to visual language information necessary for discriminating languages may exist in early life.
To confirm an optimal period, adults who had acquired English as a second language were tested. If English was learned before age 6 years, adults discriminated English and French, but if English was learned after age 6, adults performed at chance. Experience with visual speech information in early childhood influences adult performance.
To better understand the developmental trajectory of visual language discrimination, visual correlates of phonetic segments and rhythmical information were examined. When clips were manipulated to remove rhythmical information, infants used segmental visual phonetic cues to discriminate languages at 4, but not 8 months old. This suggests that a decline in non-native visual phonetic discrimination (similar to the decline seen for non-native auditory phonetic information; Werker & Tees, 1984), may be impairing language discrimination at 8 months.
Infants as young as newborn use rhythmical auditory information to discriminate languages presented forward, but not backward (Mehler et al., 1988). This thesis showed that both 4 and 8-month-old infants could discriminate French from English when shown reversed language clips. Unlike auditory speech, reversed visual speech must conserve cues that permit language discrimination.
Infants’ abilities to distinguish languages using visual speech parallel auditory speech findings, but also diverge to highlight unique characteristics of visual speech. Together, these studies further enrich our understanding of how infants come to recognize and learn their native language(s).
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Lages, Martin. "Bias in visual discrimination and detection." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298304.
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Martinez, Laura. "Auditory-visual intermodal discrimination in chimpanzees." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/126577.
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Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第14990号
理博第3469号
新制||理||1508(附属図書館)
27440
UT51-2009-R714
京都大学大学院理学研究科生物科学専攻
(主査)教授 松沢 哲郎, 准教授 友永 雅己, 教授 髙井 正成
学位規則第4条第1項該当
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De, Pasquale Roberto. "Visual discrimination learning and LTP-like changes in primary visual cortex." Doctoral thesis, Scuola Normale Superiore, 2009. http://hdl.handle.net/11384/85939.
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Mulder, Jan A. "Using discrimination graphs to represent visual knowledge." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25943.
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This dissertation is concerned with the representation of visual knowledge. Image features often have many different local interpretations. As a result, visual interpretations are often ambiguous and hypothetical. In many model-based vision systems the problem of representing ambiguous and hypothetical interpretations is not very specifically addressed. Generally, specialization hierarchies are used to suppress a potential explosion in local interpretations. Such a solution has problems, as many local interpretations cannot be represented by a single hierarchy.
As well, ambiguous and hypothetical interpretations tend to be represented along more than one knowledge representation dimension limiting modularity in representation and control. In this dissertation a better solution is proposed.
Classes of objects which have local features with similar appearance in the image are represented by discrimination graphs. Such graphs are directed and acyclic. Their leaves represent classes of elementary objects. All other nodes represent abstract (and sometimes unnatural) classes of objects, which intensionally represent the set of elementary object classes that descend from them. Rather than interpreting each image feature as an elementary object, we use the abstract class that represents the complete set of possible (elementary) objects. Following the principle of least commitment, the interpretation of each image feature is repeatedly forced into more restrictive classes as the context for the image feature is expanded, until the image no longer provides subclassification information. This approach is called discrimination vision, and it has several attractive features. First, hypothetical and ambiguous interpretations can be represented along one knowledge representation dimension. Second, the number of hypotheses represented for a single image feature can be kept small. Third, in an interpretation graph competing hypotheses can be represented in the domain of a single variable. This often eliminates the need for restructuring the graph when a hypothesis is invalidated. Fourth, the problem of resolving ambiguity can be treated as a constraint satisfaction problem which is a well researched problem in Computational Vision.
Our system has been implemented as Mapsee-3, a program for interpreting sketch maps. A hierarchical arc consistency algorithm has been used to deal with the inherently hierarchical discrimination graphs. Experimental data show that, for the domain implemented, this algorithm is more efficient than standard arc consistency algorithms.Science, Faculty of
Computer Science, Department of
Graduate
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Saylor, Stephanie A. "CONTEXTUAL EFFECTS ON FINE ORIENTATION DISCRIMINATION TASKS." Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1061319633.
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Kelling, Angela S. "Simple visual discrimination training of the giant panda (Ailuropoda melanoleuca)." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04072004-180031/unrestricted/kelling%5Fangela%5Fs%5F200312%5Fms.pdf.
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Ocansey, Stephen. "How does visual crowding interfere with depth discrimination?" Thesis, Anglia Ruskin University, 2016. http://arro.anglia.ac.uk/701527/.
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The presence of flanking targets can impair depth discrimination, presumably through a form of lateral interaction or visual crowding. This study investigates how stereoscopic crowding interferes with foveal depth discrimination when tests and flanking stimuli of different spatial configuration are located on and off the horopter in normal subjects by using psychophysical means. The magnitude of crowding increased when the flanking bars were in close spatial proximity to the test, between 1 to 2 arc min, and returned to unflanked levels for wider separations of 4 arc min and beyond. The magnitude of crowding depended on the extent to which the test and the flanking bars width matched. When flankers were placed at the optimum crowding distance (OCD) and displaced off the horopter, crowding reduced but the flanker effect was restored at greater flanker disparity. On the contrary, flankers positioned at the least crowding distance (LCD) at the onset generally showed an increase in thresholds from the fixation plane with increasing flanker disparity. Crowding was produced at similar small test- flanker separation for the range of 0.5 to 4 cpd flanker spatial frequency composition used. The magnitude of crowding was greater for test and flanker of similar spatial frequency, though some crowding was produced when their spatial frequency differed. Overall, the results confirm previous reports showing that depth discrimination thresholds increase in the presence of flanking contours, but in addition suggest that disparity integration relative to the fixation demonstrates a dichotomy of fine and coarse mechanisms driven by salience attraction. Additionally, the results show that the crowding effect can be reduced by depth cues related to the width, and disparity of flanking stimuli. The crowding effect may be attributed to the action of local disparity interactions, but suggest the involvement of Gestalt factors (for larger flanker widths) and luminance flux (for thinner flanker widths) factors.
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Ocansey, Stephen. "How does visual crowding interfere with depth discrimination?" Thesis, Anglia Ruskin University, 2016. https://arro.anglia.ac.uk/id/eprint/701527/1/Ocansey_2016b.pdf.
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The presence of flanking targets can impair depth discrimination, presumably through a form of lateral interaction or visual crowding. This study investigates how stereoscopic crowding interferes with foveal depth discrimination when tests and flanking stimuli of different spatial configuration are located on and off the horopter in normal subjects by using psychophysical means.
The magnitude of crowding increased when the flanking bars were in close spatial proximity to the test, between 1 to 2 arc min, and returned to unflanked levels for wider separations of 4 arc min and beyond. The magnitude of crowding depended on the extent to which the test and the flanking bars width matched. When flankers were placed at the optimum crowding distance (OCD) and displaced off the horopter, crowding reduced but the flanker effect was restored at greater flanker disparity. On the contrary, flankers positioned at the least crowding distance (LCD) at the onset generally showed an increase in thresholds from the fixation plane with increasing flanker disparity. Crowding was produced at similar small test- flanker separation for the range of 0.5 to 4 cpd flanker spatial frequency composition used. The magnitude of crowding was greater for test and flanker of similar spatial frequency, though some crowding was produced when their spatial frequency differed.
Overall, the results confirm previous reports showing that depth discrimination thresholds increase in the presence of flanking contours, but in addition suggest that disparity integration relative to the fixation demonstrates a dichotomy of fine and coarse mechanisms driven by salience attraction. Additionally, the results show that the crowding effect can be reduced by depth cues related to the width, and disparity of flanking stimuli. The crowding effect may be attributed to the action of local disparity interactions, but suggest the involvement of Gestalt factors (for larger flanker widths) and luminance flux (for thinner
flanker widths) factors.
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Fraser, Ian Hamilton. "Temporal discrimination and integration in visual pattern perception." Thesis, University of Aberdeen, 1986. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU003837.
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The literature on models of pattern recognition was reviewed and it was revealed that there is a paucity of information concerning temporal factors and their effects on pattern perception. A method for ivestigating these aspects was outlined which entails the fragmentation of a stimulus and its presentation over time. This type of stimulus presentation has revealed that the visual system appears to harbour biases towards parsing the internal or external features from the outline. In addition there were perceptual advantages in terms of processing speed and fewer errors when the outline occurred first in the sequence of stimulus fragments. Both of these biases appear strongest when meaningful as opposed to non-representational stimuli are used. It was concluded that these results can be best explained in terms of a two stage processing model. The first stage involves a process of building up an internal representation (much along the lines of David Marr's model). The second stage involves a cognitively driven scanning process which compares the representation with the items in the subject's picture vocabulary. This scanning process is probably hierarchically organised.
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Rensink, Ronald Andy. "On the visual discrimination of self-similar random textures." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26059.
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This work investigates the ability of the human visual system to discriminate self-similar Gaussian random textures. The power spectra of such textures are similar to themselves when rescaled by some factor h > 1. As such, these textures provide a natural domain for testing the hypothesis that texture perception is based on a set of spatial-frequency channels characterized by filters of similar shape.
Some general properties of self-similar random textures are developed. In particular, the relations between their covariance functions and power spectra are established, and are used to show that many self-similar random textures are stochastic fractals. These relations also lead to a simple texture-generation algorithm that allows independent and orthogonal variation of several properties of interest.
Several sets of psychophysical experiments are carried out to determine the statistical properties governing the discrimination of self-similar line textures. Results show that both the similarity parameter H and the scaling ratio h influence discriminability. These two quantities, however, are insufficient to completely characterize perceived texture.
The ability of the visual system to discriminate between various classes of self-similar random texture is analyzed using a simple multichannel model of texture perception. The empirical results are found to be compatible with the hypothesis that texture perception is mediated by the set of spatial-frequency channels putatively involved in form vision.Science, Faculty of
Computer Science, Department of
Graduate
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Barense, Morgan Dorough. "Complex visual discrimination and the human medial temporal lobe." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612708.
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Hodgskiss, Dean Leslie. "Towards improved visual stimulus discrimination in an SSVEP BCI." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/11283.
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The dissertation investigated the influence of stimulus characteristics, electroencephalographic (EEG) electrode location and three signal processing methods on the spectral signal to noise ratio (SNR) of Steady State Visual Evoked Potentials (SSVEPs) with a view for use in Brain-Computer Interfaces (BCIs). It was hypothesised that the new spectral baseline processing method introduced here, termed the 'activity baseline', would result in an improved SNR.
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Koba, Reiko. "Experimental studies on visual sex discrimination in Japanese monkeys." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136948.
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King, Robert A. "Perceptual grouping selection rules in visual search : methods of sub-group selection in multiple target visual search tasks." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/32821.
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Dakin, S. C. "The visual representation of texture." Thesis, University of Stirling, 1994. http://hdl.handle.net/1893/3503.
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This research is concerned with texture: a source of visual information, that has motivated a huge amount of psychophysical and computational research. This thesis questions how useful the accepted view of texture perception is. From a theoretical point of view, work to date has largely avoided two critical aspects of a computational theory of texture perception. Firstly, what is texture? Secondly, what is an appropriate representation for texture? This thesis argues that a task dependent definition of texture is necessary, and proposes a multi-local, statistical scheme for representing texture orientation. Human performance on a series of psychophysical orientation discrimination tasks are compared to specific predictions from the scheme. The first set of experiments investigate observers' ability to directly derive statistical estimates from texture. An analogy is reported between the way texture statistics are derived, and the visual processing of spatio-luminance features. The second set of experiments are concerned with the way texture elements are extracted from images (an example of the generic grouping problem in vision). The use of highly constrained experimental tasks, typically texture orientation discriminations, allows for the formulation of simple statistical criteria for setting critical parameters of the model (such as the spatial scale of analysis). It is shown that schemes based on isotropic filtering and symbolic matching do not suffice for performing this grouping, but that the scheme proposed, base on oriented mechanisms, does. Taken together these results suggest a view of visual texture processing, not as a disparate collection of processes, but as a general strategy for deriving statistical representations of images common to a range of visual tasks.
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Waterston, Michael. "Improved discrimination of visual stimuli following repetitive transcranial magnetic stimulation." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86887.
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Repetitive transcranial magnetic stimulation (rTMS) at certain frequencies increases thresholds for motor evoked potentials and phosphenes following stimulation of motor or visual cortex. Consequently rTMS is often assumed to introduce a "virtual lesion" in stimulated brain regions, with correspondingly diminished behavioral performance. Here we investigated the effects of rTMS to visual cortex on subjects' ability to perform visual psychophysical tasks. Contrary to expectations of a visual deficit, we find that rTMS often improves the discrimination of visual features. For coarse orientation tasks, discrimination of a static stimulus improved consistently following theta-burst stimulation of the occipital lobe. Using a reaction-time task, we found that these improvements occurred throughout the visual field and lasted beyond one hour post-rTMS. Low-frequency (1 Hz) stimulation yielded similar improvements. Finally, we observed improved depth discrimination following high-frequency rTMS to V3A, and these effects were highly task-specific, yielding improved discrimination of disparity but not orientation. Overall our results suggest that rTMS generally improves or has no effect on visual acuity, with the nature of the effect depending on the type of stimulation and the task. We interpret our results in the context of an ideal-observer model of visual perception.La stimulation magnétique transcrânienne répétitive (rTMS) à certains seuils fréquences augmente pour potentiels évoqués moteurs et phosphènes suite d'une stimulation du moteur ou du cortex visuel. Par conséquent rTMS suppose souvent de mettre en place une lésion «virtuel» des régions cérébrales sollicitées, avec des performances comportementales réduit d'autant. Ici, nous avons étudié les effets de la rTMS au cortex visuel sur l'aptitude des sujets d'effectuer des tâches visuelles psychophysiques. Contrairement aux attentes d'un déficit visuel, nous constatons que rTMS améliore souvent la discrimination des caractéristiques visuelles. Pour les tâches d'orientation grossière, de la discrimination d'un stimulus statique améliorée à la suite constamment theta-burst stimulation du lobe occipital. L'utilisation d'un temps de réaction tâche, nous avons constaté que ces améliorations se sont produites tout au long du champ visuel et a duré plus d'un heure après l'rTMS. Basse fréquence (1 Hz) stimulation permis des améliorations similaires. Enfin, nous avons observé une meilleure discrimination en profondeur suivant à haute fréquence rTMS à V3A, et ces effets ont été très tâches spécifiques, ce qui donne de faciliter la distinction de disparité, mais pas l'orientation. L'ensemble, nos résultats suggèrent que rTMS améliore de manière générale ou n'a pas d'effet sur l'acuité visuelle, avec la nature de l'effet en fonction du type de stimulation et de la tâche. Nous interprétons nos résultats dans le contexte d'un modèle idéal-observateur de la perception visuelle.
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Maderitz, Cecelia R. "A COMPARISON OF SIMPLE AND COMPLEX AUDITORY VISUAL DISCRIMINATION TRAINING." Youngstown State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1348842474.
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Mazurek, Mark. "Neural mechanisms for combining information in a visual discrimination task /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/10649.
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Reinke, Karen Sue 1965. "Visual and neural plasticity: A study of line orientation discrimination." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282794.
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Discrimination learning, the ability to better discriminate fine perceptual changes, is an important skill humans possess. In the present set of studies, some of the parameters that govern line orientation discrimination teaming are examined along with theories of the mechanisms underlying such learning. Specifically, three questions are addressed. First, how does training on one part of the orientation dimension affect the rest of that dimension? When subjects were trained with one pair of orientations at one retinal location, learning that was a true change in perception did occur. When subjects were tested with a novel orientation, rotated 90 degrees at the same retinal location, significant interference was found. Next, how training at one part of the orientation dimension affects the retinal location dimension was examined. Retinal location is coded in the same part of the brain as orientation and therefore may also be affected by training. Training with one pair of orientations at one retinal location did have an effect on at least one neighboring retinal location such that performance dropped below baseline, indicating interference. Finally, how training on the entire dimension of orientation affects the process of discrimination learning was examined. Training subjects with four pairs of orientations that span the entire orientation dimension did allow learning to occur. This learning may not have been a true change in perception. When tested with a novel, intermediate pair of orientations, previous learning may have positively transferred, but did not appear to interfere. Testing with a neighboring retinal location showed no sign of interference as did training with one pair of orientations. Based on the neurophysiological studies on monkeys by Recanzone et al. (1992; 1993), it was suggested that increased discrimination ability occurs through the reorganization of cortical sensory maps such that there is more cortical area devoted to the practiced stimuli. The results of the present set of studies suggest that discrimination learning does occur by recruiting neighboring cells to respond to the practiced stimuli when learning is occurring for one part of a dimension. When learning occurs for an entire dimension, a different mechanism appears to be at work.
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Lalonde, Jasmin. "Task-dependent transfer of perceptual to memory representations during delayed spatial frequency discrimination." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33911.
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Discrimination thresholds were obtained during a delayed spatial frequency discrimination task. In Experiment 1, we found that presentation of a mask 3 s before onset of a reference Gabor patch caused selective interference in a subsequent discrimination task. However, a 10 s interval abolished this masking effect. In Experiment 2, the mask was associated with a second spatial frequency discrimination task so that a representation of the mask had to be coded into short-term perceptual memory. The presence of this second discrimination task now caused similar interference effects on the primary discrimination task at both the 3 s and 10 s ISI conditions. The different results from these two experiments are best explained by a two-step perceptual memory mechanism. The results also provide further insight into the conditions under which stimulus representations are shared between the perceptual and memory domains.
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Arsenault, Serge A. "The dynamics of texture segregation : a task comparison approach." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69546.
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The time course of texture segregation was studied for three different measures of segregation (detection, localization and identification of an embedded texture region) under three different raster width conditions (26$ sp prime$, 43$ sp prime$ and 61$ sp prime$ of arc) by using a backward masking paradigm. The masking data were described with an exponential model the parameters of which represent rate of performance improvement and asymptotic performance level. The results indicate that: (1) information supporting localization accrues more rapidly than information supporting identification, (2) increasing element spacing had a more detrimental effect on identification than on localization, (3) under most spacing conditions, performance on detection fell between that for localization and identification. In conclusion, these three widely used texture segregation tasks cannot be considered equivalent measures of a single process. However, comparisons among their respective time courses may enable us to better characterize the mechanisms underlying the segregation process.
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Ho, Pik-ki, and 何碧琪. "Visual crowding and binocular vision: the locus of crowding relative to binocular rivalry and fusion." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43572091.
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Ho, Pik-ki. "Visual crowding and binocular vision the locus of crowding relative to binocular rivalry and fusion /." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43572091.
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Harrison, Maria. "An exploration of pre-attentive visual discrimination using event-related potentials." Thesis, University of Westminster, 2013. https://westminsterresearch.westminster.ac.uk/item/8yzqq/an-exploration-of-pre-attentive-visual-discrimination-using-event-related-potentials.
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The Mismatch Negativity (MMN) has been characterised as a ‘pre-attentive’ component of an Event-Related Potential (ERP) that is related to discriminatory processes. Although well established in the auditory domain, characteristics of the MMN are less well characterised in the visual domain. The five main studies presented in this thesis examine visual cortical processing using event-related potentials. Novel methodologies have been used to elicit visual detection and discrimination components in the absence of a behavioural task. Developing paradigms in which a behavioural task is not required may have important clinical applications for populations, such as young children, who cannot comply with the demands of an active task. The ‘pre-attentive’ nature of visual MMN has been investigated by modulating attention. Generators and hemispheric lateralisation of visual MMN have been investigated by using pertinent clinical groups. A three stimulus visual oddball paradigm was used to explore the elicitation of visual discrimination components to a change in the orientation of stimuli in the absence of a behavioural task. Monochrome stimuli based on pacman figures were employed that differed from each other only in terms of the orientation of their elements. One such stimulus formed an illusory figure in order to capture the participant’s attention, either in place of, or alongside, a behavioural task. The elicitation of a P3a to the illusory figure but not to the standard or deviant stimuli provided evidence that the illusory figure captured attention. A visual MMN response was recorded in a paradigm with no task demands. When a behavioural task was incorporated into the paradigm, a P3b component was elicited consistent with the allocation of attentional resources to the task. However, visual discrimination components were attenuated revealing that the illusory figure was unable to command all attentional resources from the standard deviant transition. The results are the first to suggest that the visual MMN is modulated by attention. Using the same three stimulus oddball paradigm, generators of visual MMN were investigated by recording potentials directly from the cortex of an adolescent undergoing pre-surgical evaluation for resection of a right anterior parietal lesion. To date no other study has explicitly recorded activity related to the visual MMN intracranially using an oddball paradigm in the absence of a behavioural task. Results indicated that visual N1 and visual MMN could be temporally and spatially separated, with visual MMN being recorded more anteriorly than N1. The characteristic abnormality in retinal projections in albinism afforded the opportunity to investigate each hemisphere in relative isolation and was used, for the first time, as a model to investigate lateralisation of visual MMN and illusory contour processing. Using the three stimulus oddball paradigm, no visual MMN was elicited in this group, and so no conclusions regarding the lateralisation of visual MMN could be made. Results suggested that both hemispheres were equally capable of processing an illusory figure. As a method of presenting visual test stimuli without conscious perception, a continuous visual stream paradigm was developed that used a briefly presented checkerboard stimulus combined with masking for exploring stimulus detection below and above subjective levels of perception. A correlate of very early cortical processing at a latency of 60-80 ms (CI) was elicited whether stimuli were reported as seen or unseen. Differences in visual processing were only evident at a latency of 90 ms (CII) implying that this component may represent a correlate of visual consciousness/awareness. Finally, an oddball sequence was introduced into the visual stream masking paradigm to investigate whether visual MMN responses could be recorded without conscious perception. The stimuli comprised of black and white checkerboard elements differing only in terms of their orientation to form an x or a +. Visual MMN was not recorded when participants were unable to report seeing the stimulus. Results therefore suggest that behavioural identification of the stimuli was required for the elicitation of visual MMN and that visual MMN may require some attentional resources. On the basis of these studies it is concluded that visual MMN is not entirely independent of attention. Further, the combination of clinical and non-clinical investigations provides a unique opportunity to study the characterisation and localisation of putative mechanisms related to conscious and non-conscious visual processing.
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Michel, Rachel Keyes. "Visual perception, search, and attention." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/29580.
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Crabtree, Charles E. "Short-Term Visual Deprivation, Tactile Acuity, and Haptic Solid Shape Discrimination." TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1387.
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The visual cortex of human observers changes its functionality in response to visual deprivation (Boroojerdi et al., 2000). Behavioral studies have recently documented enhanced tactile abilities following a short period of visual deprivation (Facchini & Aglioti, 2003; Weisser, Stilla, Peltier, Hu, & Sathian, 2005). The current study investigated the effects of visual deprivation on two unique tactile tasks. While Facchini and Aglioti observed significant effects of visual deprivation, neither Wong, Hackeman, Hurd, and Goldreich (2011) nor Merabet et al. (2008) observed these effects. Corroborating these more recent results, no difference in grating orientation discrimination performance was observed between the sighted and visually deprived participants in the first experiment. A significant effect of experience was seen in both groups, however, irrespective of the deprivation period of 90 minutes. The second experiment immediately followed the conclusion of the first experiment. Using the same stimuli and procedures from past experiments (Norman, Clayton, Norman, & Crabtree, 2008), it investigated the participants’ haptic discrimination of 3-dimensional object shape. Again, no significant difference in performance was found between the sighted and visually deprived participants. Together, the current results show that a brief period of visual deprivation (1.5 hours) produces no significant behavioral changes for these tactile and haptic tasks.
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Muller, Hermann Josef. "The effect of selective spatial attention on peripheral discrimination thresholds." Thesis, Durham University, 1986. http://etheses.dur.ac.uk/7060/.
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Experiments were conducted to investigate the role of attention in peripheral detection and discrimination. Advance spatial cues informed subjects about likely target positions; the task required to detect/discriminate plus localise a target briefly presented at cued or uncued locations, with accuracy as the dependent variable ("cost-benefit" analysis).Spatial cueing produced reliable advantages for cued over uncued locations, in single and in multiple element displays. However, costs plus benefits were less marked for single displays. Thus, advance knowledge of the likely target location enhances performance also when there are no competing stimuli present in the visual field. But costs plus benefits are smaller because single target onsets at uncued locations summon attention in the same "automatic" fashion as peripheral cues. Peripheral cues trigger a rapid facilitatory component (automatic), fading out within 300 msec after cue onset. Facilitation is then maintained by a less effective mechanism (controlled). Central cues initiate only this second component. Sustained, controlled, orienting in response to central cues is interruptable by automatic orienting in response to uninformative peripheral flashes. Interruption also occurs when irrelevant flashes compete with peripheral cues. However, interference is less marked for the early automatic than for the following controlled orienting component. Indication of a second position (four-location display) to be most likely resulted in a marked sensitivity gain for this position, relative to uncued locations in a single cue condition. That is, attention could be simultaneously shared between two cued positions. For a luminance detection task (single target), cued locations showed no advantage in sensitivity; but for letter detection tasks (target plus distractors), there was a marked priming effect. That is, letter detection is capacity limited, whereas luminance detection is not. In all tasks, decision criteria are largely preset according to a-priori target probabilities assigned to particular locations, i.e. more liberal for cued and more conservative for uncued locations.
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Tucker, Andrew James. "Visual space attention in three-dimensional space." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070301.085637/index.html.
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Thesis (PhD) - Faculty of Life and Social Sciences, Swinburne University of Technology, 2006.Submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy, Faculty of Life and Social Sciences, Swinburne University of Technology - 2006. Typescript. "March 2006". Includes bibliographical references (p. 153-173).
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McLean, Jennifer E. "Processing capacity of visual perception and memory encoding /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/9019.
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Best, Lisa A. "Graphical perception of nonlinear trends : discrimination and extrapolation /." Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/BestLA2001.pdf.
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Fair, Joseph Edward. "Infant Facial Discrimination and Perceptual Narrowing." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/2154.
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During the early stages of infant development the capacity for perceptual (i.e., visual) discrimination is shaped by infants' perceptual experience. Perceptual narrowing is one process hypothesized to account for developmental change. Perceptual narrowing research often demonstrates that infants before 6 months of age are able to discriminate a wide variety of events whereas infants beyond 6 months of age seemingly "lose" some perceptual abilities. Two investigations are proposed to examine the claim that younger, but not older infants can discriminate faces across species. The purpose of Experiment 1 was to determine whether an increase in familiarization and trial times would result in cross-species facial (i.e. faces of macaques) discrimination in 12-month-olds. The hypothesis was supported, adding evidence that perceptual discrimination becomes more constricted, or less efficient with age, but does not decline. Experiment 2 examined whether reducing both the time of familiarization and comparison time by 50% would allow infants sufficient time to discriminate. Results were consistent with the hypothesis and previous studies were corroborated. These findings highlight the important role of perceptual experience in young infants' perceptual discrimination abilities and provide a greater degree of clarity regarding present use of the concept perceptual narrowing.
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Pallett, Pamela Mitchell. "The fundamentals of configuration in face perception and discrimination." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3336646.
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Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed Jan. 9, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Lavis, Yvonna Marie Psychology Faculty of Science UNSW. "An investigation of the mechanisms responsible for perceptual learning in humans." Publisher:University of New South Wales. Psychology, 2008. http://handle.unsw.edu.au/1959.4/42882.
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Discrimination between similar stimuli is enhanced more by intermixed pre-exposure than by blocked pre-exposure to those stimuli. The salience modulation account of this intermixed-blocked effect proposes that the unique elements of intermixed stimuli are more salient than those of blocked stimuli. The inhibition account proposes that inhibitory links between the unique elements of intermixed stimuli enhance discrimination. The current thesis evaluated the two accounts in their ability to explain this effect in humans. In Experiments 1 and 2, categorisation and same-different judgements were more accurate for intermixed than for blocked stimuli. This indicates that intermixed pre-exposure decreases generalisation and increases discriminability more than does blocked pre-exposure. In Experiments 3 ?? 5, same-different judgements were more accurate when at least one of the two stimuli was intermixed. This enhanced discrimination was not confined to two stimuli that had been directly intermixed. These results are better explained by salience modulation than by inhibition. Experiments 6 ?? 8 employed dot probe tasks, in which a grid stimulus was followed immediately by a probe. Neither intermixed nor blocked stimuli showed facilitated reaction times when the probe appeared in the location of the unique element. In Experiments 9 ?? 11 participants learned to categorise the intermixed unique elements more successfully than the blocked unique elements, but only when the unique elements were presented on a novel background during categorisation. Experiments 6 ?? 11 provide weak evidence that the intermixed unique elements are more salient than their blocked counterparts. In Experiment 12, participants were presented with the shape and location of a given unique element, and were required to select the correct colour. Performance was more accurate for intermixed than for blocked unique elements. In Experiment 13, participants learned to categorise intermixed, blocked and novel unique elements. Performance was better for intermixed than for blocked and novel unique elements, which did not differ. None of the proposed mechanisms for salience modulation anticipate these results. The intermixed-blocked effect in human perceptual learning is better explained by salience modulation than by inhibition. However, the salience modulation accounts that have been proposed received little support. An alternative account of salience modulation is considered.
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Andersson, Isabell. "Modes of Apprehension, and Indicators thereof, in Visual Discrimination of Relative Mass." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-108214.
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Gaalema, Diann Ellen. "Food Choice, Reinforcer Preference, and Visual Discrimination in Monitor Lizards (Varanus Spp.)." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19799.
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Learning in reptiles has been studied with a variety of methods and included numerous species. However, research on learning in lizards has generally focused on spatial memory and has used only a few species. No research has specifically investigated and documented the use of visual discrimination in monitor lizards. The ability of monitor lizards (Varanus spp.) to discriminate between visual stimuli was investigated. Subjects were tested on acquisition and two reversals of a discrimination task between black and white stimuli. A food-choice procedure was used to determine if consistent rankings of food items could be determined using a multiple-stimulus choice procedure. The functional value of the rankings was assessed using a progressive ratio technique. The subjects formed stable food preferences, which were reflected in increased response requirement completed for preferred items and subjects did successfully learn the initial discrimination task and the following reversals.
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Perry, C. "Studies by computer simulation of visual detection and discrimination of astronomical objects." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37816.
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McNeil, Jane. "WORKPLACE DISCRIMINATION AND VISUAL IMPAIRMENT: AN ANALYSIS OF EEOC CHARGES AND RESOLUTIONS." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/4081.
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Workplace discrimination for individuals with visual impairments in the U.S. is an ongoing issue dating before the founding of the EEOC and the enactment of the ADA. Despite laws enacted to protect against unequal treatment in the workplace, the EEOC continues to receive submissions of formal discrimination charges from individuals with visual impairments.
The workplace is experiencing changes with increasing amounts of older adults, women, minorities, and the use of technology and the Internet. By examining characteristics of the discrimination charges and the resulting outcomes, the knowledge gained can describe the current situation and the historical progression of workplace discrimination for individuals with visual impairments. The purpose of this cross-sectional study is to understand through descriptive, non-parametric, and logistical regression analyses of secondary data, meaningful associations regarding workplace discrimination and Americans with visual impairments.
Study results showed that charging party characteristics of age, gender, and race were found to be predictive of types of discrimination charges and resolutions outcomes. Respondent characteristics of employer region of location, size, and industry were also found to be predictive of types of discrimination charges and resolution outcomes. Differences were revealed between discrimination charges before and after the enactment of the ADAAA, yet not between resolution outcomes before and after the enactment of the ADAAA. Additionally, discrimination charges and resolution outcomes were determined to be associated with one another. Implications for employees, employers, and professionals who work with individuals with visual impairments are addressed and recommendations for further research are provided.
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Campbell, Holly Renee. "Spatially-invariant discrimination of visual pattern orientationin the blow fly Phaenicia sericata." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284181.
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Despite a wealth of information regarding visual processing in flies, little is known regarding their pattern discrimination abilities and the neural correlates of pattern recognition. The work presented here provides evidence of learned visual discriminations of complex visual patterns in the blowfly, Phaenicia sericata. A learning and memory assay was developed to determine the pattern-orientation discrimination ability of blowflies. Individual flies were trained to discriminate between pairs of visual patterns that differed in the orientation of their composite lines. During training and subsequent testing trials flies exhibited a preference for the previously-rewarded visual stimulus. Flies learned to discriminate between horizontal and vertical gratings, +45° and -45° gratings, and vertical and +5° gratings. Among four possible underlying mechanisms used to discriminate between these sets of patterns, hypothetical orientation-selective neurons are uniquely capable of discriminating between all sets of discriminated patterns. One previous theory of insect vision suggests that in order for an insect to recognize previously learned visual images, the insect must align the current retinal input with the region of the retina with which the pattern was first viewed and learned (Wehner, 1981; Dill et al., 1993). To address this theory of retinotopic matching, a detailed analysis was made of fly behavior during the discrimination process. Both the spatial structure of the approaches to the visual cues and the range of body orientations used by individual flies demonstrated that Phaenicia approaches the visual cue from an unique vantage point from trial to trial and, therefore, retinotopic matching is not necessary for the recognition of pattern orientation by blowflies. To test for the existence of orientation-selective neurons in Phaenicia, the lobula neuropil was impaled for intracellular recording. Two neurons exhibited directional motion preferences indicative of a possible role in the detection of expanding, oblique edges during approach to visual cues. Two additional neurons with combined responses to both directional motion and the orientation of the stimulus were recorded. These data support the hypothesis that the dipteran lobula processes information regarding the orientation of visual stimuli.
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Wells, Mary Anne. "The role of darkness in students' conceptions about light propagation and vision." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 100 p, 2007. http://proquest.umi.com/pqdlink?did=1253511301&Fmt=7&clientId=79356&RQT=309&VName=PQD.
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Hailston, Kenneth. "Investigating the roles of features and priming in visual search." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29731.
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Thesis (Ph.D)--Psychology, Georgia Institute of Technology, 2009.Committee Chair: Dr. Elizabeth T. Davis; Committee Member: Dr. Gregory M. Corso; Committee Member: Dr. Krishnankutty Sathian; Committee Member: Dr. Paul Corballis; Committee Member: Dr. Wendy A. Rogers. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Hailston, Kenneth W. "Effects of Priming Visual Relatedness and Expectancy on Visual Search Performance." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7498.
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The current study examined two means of reducing uncertainty in visual search: 1) visual relatedness of a prime to the target (a data-driven, bottom-up processing) and 2) expectancy (a top-down process based on the proportion of validly primed trials). The two processes were decoupled using a short and a long inter-stimulus interval (ISI) to examine their time course in visual search. Competing hypotheses were contrasted in order to determine whether relatedness is associated with iconic memory (Neely, 1977) or a longer lasting visual-structural implicit memory (Schacter and Cooper, 1995) and what role participant expectancy plays in visual search performance.
Twelve participants engaged in a discrimination task and a visual search task. The obtained results suggest that visual relatedness is a bottom-up process, probably mediated by a short-term iconic store that affects search performance early, but whose effects rapidly decay. They also suggest that expectancy is a top-down process that requires time to build up before it can affect visual search performance, but whose effects are more long lasting than visual relatedness.
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D'Aquisto, Joseph Paul. "Visual discrimination of French and English in inter-speech and speech-ready position." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50258.
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This study investigates the ability of observers to discriminate between French and English using visual-only stimuli. This study differs from prior studies because it specifically uses inter-speech(ISP) and speech-ready tokens rather than full sentences. The main purpose of this research was to answer if observers could successfully discriminate French from English by watching video clips of speakers engaged in ISP and speech-ready positions with the audio removed. Two experiments were conducted; the first experiment focuses on native English vs. non-native English speakers and the second experiment focuses on native English vs. native French speakers which expands further on the data in the first experiment. The results support the view that observers can visually distinguish their native language even in the absence of segmental information.Arts, Faculty of
Linguistics, Department of
Graduate
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Dewhurst, Richard Charles. "Evaluating strategies for visual search and stimulus discrimination : implications for training eye-movements." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10811/.
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Eight experiments are described exploring the consequences of training eye-movements. Training is related to Findlay & Walker’s (1999) model of saccade generation, and consists of strategies for visual search and stimulus discrimination. These two components are separated in an effort to link training to the hypothesised Move and Fixate centres, respectively, within Findlay & Walker’s framework. Training directed towards the Move centre thus consistently improved visual search, and in Experiments 1-4 it was also shown that training directed towards the Fixate centre could further improve performance (in terms of target response discrimination) in an additive way over Move Training alone. Experiments 5-7 investigated the idea that training which promotes activity in the Move centre, independently, may actually be detrimental. This hypothesis draws upon the reciprocal inhibitory relationship between the Move and Fixate centres described by Findlay & Walker: training people where to look may increase activity in the Move centre and consequently hinder information processing during fixational eye movements, owing to an associated diminution of activity in the Fixate centre. Partial support for this conclusion was found. When training encouraged saccades away from a task-relevant centrally located stimulus, towards a visible saccade target in the periphery, there was evidence of premature disengagement when fixating, causing sub-optimal processing of the central stimulus in the first instance (Exp. 5). However, this effect was sensitive to changes in task (Exps. 6 & 7). This may explain why Move training did not encumber performance in a driving task (Exp. 8). Nevertheless, the findings reported herein have implications for training eye-movements in applied settings, because they suggest combined eye movement training directed towards the Move and Fixate centres in concert may produce cumulative performance gains, and offset detection failures associated with a sole emphasis on visual scanning.
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Wiesemann, Elizabeth Y. "The Visual Perception of Elasticity." TopSCHOLAR®, 2008. http://digitalcommons.wku.edu/theses/75.
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Nácar, García Loreto 1988. "Language acquisition in bilingual infants : Early language discrimination in the auditory and visual domains." Doctoral thesis, Universitat Pompeu Fabra, 2016. http://hdl.handle.net/10803/511361.
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Learning language is a cornerstone in the cognitive development during the first year of life. A fundamental difference between infants growing up in monolingual versus bilingual environments is the necessity of the latter to discriminate between two language systems since very early in life. To be able to learn two different languages, bilingual infants will have to perceive the regularities of each of their two languages while keeping them separated. In this thesis we explore the differences between monolingual and bilingual infants in their early language discrimination abilities as well as the strategies that arise for each group as a consequence of their adaptation to their different linguistic environments.
In chapter two, we examine the capacities of monolingual and bilingual 4-month-old infants to discriminate between their native/dominant language from foreign ones in the auditory domain. Our results show that, in this context, bilingual and monolingual infants present different brain signals, both in the temporal and the frequency domain, when listening to their native language. The results pinpoint that discriminating the native language represents a higher cognitive cost for bilingual than for monolingual infants when only auditory information is available.
In chapter three we explore the abilities of monolingual and bilingual 8-month-old infants to discriminate between languages in the visual domain. Here we show to infants never exposed to sign languages videos of two different sign languages and we measure their discriminatory abilities using a habituation paradigm. The results show that at this age only bilingual infants can discriminate between the two sign languages. The results of a second control study points in the direction that bilinguals exploit the information coming from the face of the signer to make the distinction.
Altogether, the studies presented in this thesis investigate a fundamental ability to learn language - specially in the case of bilingual environments - which is discriminating between different languages. Compared to a monolingual environment, being exposed to a bilingual environment is characterized by receiving more information (2 languages) but with less exposure to each of the languages (on average half of the time to each of them). We argue that the developmental brain is as prepared to learn one language from birth, as it is to learn two. However, to do so, monolingual and bilingual infants will develop particular strategies that will allow them to select the relevant information from the auditory and visual domains.La adquisición del lenguaje es una pieza fundamental en el desarrollo cognitivo durante el primer año de vida. Una diferencia fundamental entre los bebés que crecen en ambientes monolingües y bilingües es que estos últimos necesitan discriminar entre dos sistemas lingüísticos desde muy temprano en la vida. Para poder aprender dos idiomas, los bebés bilingües tienen que percibir las regularidades de cada uno de sus idiomas y a la vez mantenerlos separados. En esta tesis exploramos las diferencias entre bebés monolingües y bilingües tanto en sus capacidades de discriminación tempranas, como en las estrategias que desarrolla cada grupo como consecuencia de la adaptación a su entorno lingüístico. En el segundo capítulo, examinamos la capacidad de los bebés bilingües y monolingües a los 4 meses de edad para discriminar entre la lengua nativa/dominante de otra extranjera en el dominio auditivo. Nuestros resultados muestran que, en este contexto, los bebés monolingües y bilingües presentan diferentes señales auditivas cuando escuchan su lengua nativa. Los resultados señalan que discriminar la lengua nativa representa un coste cognitivo mayor para los bebés bilingües que para los monolingües cuando sólo sólo disponen de información auditiva. En el capítulo 3, exploramos las habilidades de los bebés monolingües y bilingües a los 8 meses de edad para discriminar lenguas en el dominio visual. Aquí, mostramos a bebés que nunca han sido expuestos a lengua de signos, videos de dos lenguas de signos diferentes y medimos sus habilidades discriminatorias usando un paradigma de habituación. Los resultados muestran que a esta edad sólo los bebés bilingües son capaces de hacer la distinción y apuntan que para ello aprovechan la información proveniente de la cara de la signante.
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Corns, David Allan. "The effects of graduated stimulus change on learning efficiency in a visual discrimination task." Virtual Press, 1990. http://liblink.bsu.edu/uhtbin/catkey/720342.
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The investigation examined differences in learning efficiency produced by two different methods of discrimination training among regular placement fifth-grade pupils. It was designed to explore possible between-group differences in rate of learning, length of training, mastery rate, recall of learning, and task persistence following training. The experiment consisted of training, an interference task, and a concluding posttest. Two independent groups were formed by random assignment of subjects. The experimental group began training with graduated stimulus change trials--that is, subjects were presented with a succession of three visual discrimination tasks consisting of six trials per task designed to teach correct responding before incorrect alternatives were gradually introduced. Control subjects did not receive graduated stimulus change trials. Instead, they began each task in the training phase with more complex discriminations at trial seven. Pennies were used for reinforcement of correct choices in each group; incorrect selection resulted in no reinforcer delivery. Both groups were then administered a brief exercise designed to inhibit the recall of acquired discriminations. All subjects concluded with a 54-item posttest consisting of intermingled trials from the three-task training phase. The first 21 items were considered mandatory, but the final 33 were optional (i.e., subjects were instructed to complete as many items as they wished and informed that each correct selection earned a penny). Results indicated that graduated stimulus change (GSC) learners committed significantly fewer errors learning the discriminations and mastered significantly more of the training tasks presented than did trial-and-error learners. There was no significant difference between the two groups in the length of training nor in the degree of persistence during posttest voluntary responding. GSC subjects also committed significantly fewer errors on recall than controls although the degree of absolute forgetting in each group was not significantly different. The findings suggest that regular placement, "easy-to-teach" pupils can profit from GSC programming in several important ways. Without lengthening the training process, stimulus control methodologies can render instruction more efficient than trial-and-error procedures for nonimpaired learners. The need is apparent for further experimental research on the application of errorless discrimination procedures to other areas and levels of education.Department of Educational Psychology
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Robinson, andrea Maureen. "Blockade of Muscarinic M1 Receptors Disrupts Performance on an Attention-Demanding Visual Discrimination Task." W&M ScholarWorks, 2009. https://scholarworks.wm.edu/etd/1539626606.
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Roper, Mark. "Honeybee visual cognition : a miniature brain's simple solutions to complex problems." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/25938.
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In recent decades we have seen a string of remarkable discoveries detailing the impressive cognitive abilities of bees (social learning, concept learning and even counting). But should these discoveries be regarded as spectacular because bees manage to achieve human-like computations of visual image analysis and reasoning? Here I offer a radically different explanation. Using theoretical bee brain models and detailed flight analysis of bees undergoing behavioural experiments I counter the widespread view that complex visual recognition and classification requires animals to not only store representations of images, but also perform advanced computations on them. Using a bottom-up approach I created theoretical models inspired by the known anatomical structures and neuronal responses within the bee brain and assessed how much neural complexity is required to accomplish behaviourally relevant tasks. Model simulations of just eight large-field orientation-sensitive neurons from the optic ganglia and a single layer of simple neuronal connectivity within the mushroom bodies (learning centres) generated performances remarkably similar to the empirical result of real bees during both discrimination and generalisation orientation pattern experiments. My models also hypothesised that complex 'above and below' conceptual learning, often used to exemplify how 'clever' bees are, could instead be accomplished by very simple inspection of the target patterns. Analysis of the bees' flight paths during training on this task found bees utilised an even simpler mechanism than anticipated, demonstrating how the insects use unique and elegant solutions to deal with complex visual challenges. The true impact of my research is therefore not merely showing a model that can solve a particular set of generalisation experiments, but in providing a fundamental shift in how we should perceive visual recognition problems. Across animals, equally simple neuronal architectures may well underlie the cognitive affordances that we currently assume to be required for more complex conceptual and discrimination tasks.
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Clayton, Anna. "The Effect of Experience Upon the Visual and Haptic Discrimination of 3-D Object Shape." TopSCHOLAR®, 2004. http://digitalcommons.wku.edu/theses/544.
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Both our sense of touch and our sense of vision allow us to perceive common object properties such as size, shape, and texture. The extent of this functional overlap has been studied in relation to infant perception (Bushnell & Weinberger, 1987; Gibson & Walker, 1984; Streri, 1987; Streri & Gentaz, 2003), overlap in brain regions (Amedi, Malach, Hendler, Peled, & Zohary, 2001; Deibert, Kraut, Kermen, & Hart, 1999; James, Humphrey, Gati, Menon, & Goodale, 2002), and adult perception (Gibson, 1962, 1963, 1966; Klatzky, Lederman, & Reed, 1987; Lakatos & Marks, 1999; Norman, Norman, Clayton, Lianekhammy, & Zielke, 2004). The current experiment extended the findings of Norman et al. (2004) by examining the effect of experience upon the visual and haptic discrimination of 3-D object shape, as well as examining for differences in how long visual and haptic shape representations can be held in short-term memory. Participants were asked to compare the shapes of two objects either within a single sensory modality (both objects presented visually or haptically) or across the sensory modalities (one object presented visually, the other presented haptically) for 120 trials. Their task was to compare whether the objects possessed the "same" or "different" 3-D shapes. The objects were presented for a duration of 3 seconds each, with a 3-, 9-, or 15-second interstimulus interval (ISI) between them. Both the unimodal (visual-visual and haptichaptic) and cross-modal (visual-haptic and haptic-visual) conditions exhibited a linear pattern of learning, and were unaffected by the various ISI's used. However, different levels of discrimination accuracies were observed for the various groups with the highest level of accuracy occurring for the visual-visual group (M = 78.65 % correct) and the lowest level of accuracy occurring for the haptic-visual group (M = 65.31 % correct). Different patterns of errors for "same" versus "different" trials were observed for the unimodal and cross-modal conditions. Taken together, the results of the current experiment give us a better understanding of the similarities and differences that exist between the visual and haptic sensory modalities representations of 3-D object shape.