Journal articles on the topic 'Random walks in symmetric exclusion processes'

Abstract We consider the symmetric exclusion process on suitable random grids that approximate a compact Riemannian manifold. We prove that a class of random walks on these random grids converge to Brownian motion on the manifold. We then consider the empirical density field of the symmetric exclusion process and prove that it converges to the solution of the heat equation on the manifold.

We find the first-hit distributions of symmetric randomized random walks on ℝ with exponential lifetime using prediction formulas for Gaussian stationary autoregressive processes, associated with the random walks.

We find the first-hit distributions of symmetric randomized random walks on ℝ with exponential lifetime using prediction formulas for Gaussian stationary autoregressive processes, associated with the random walks.

Symmetric random walks can be arranged to converge to a Wiener process in the area of normal deviation. However, random walks and Wiener processes have, in general, different asymptotics of the large deviation probabilities. The action functionals for random-walks and Wiener processes are compared in this paper. The correction term is calculated. Exit problem and stochastic resonance for random-walk-type perturbation are also considered and compared with the white-noise-type perturbation.

Abstract We investigate the long-term behavior of a random walker evolving on top of the simple symmetric exclusion process (SSEP) at equilibrium, in dimension one. At each jump, the random walker is subject to a drift that depends on whether it is sitting on top of a particle or a hole, so that its asymptotic behavior is expected to depend on the density $$\rho \in [0, 1]$$ ρ ∈ [ 0 , 1 ] of the underlying SSEP. Our first result is a law of large numbers (LLN) for the random walker for all densities $$\rho $$ ρ except for at most two values $$\rho _-, \rho _+ \in [0, 1]$$ ρ - , ρ + ∈ [ 0 , 1 ] . The asymptotic speed we obtain in our LLN is a monotone function of $$\rho $$ ρ . Also, $$\rho _-$$ ρ - and $$\rho _+$$ ρ + are characterized as the two points at which the speed may jump to (or from) zero. Furthermore, for all the values of densities where the random walk experiences a non-zero speed, we can prove that it satisfies a functional central limit theorem (CLT). For the special case in which the density is 1/2 and the jump distribution on an empty site and on an occupied site are symmetric to each other, we prove a LLN with zero limiting speed. We also prove similar LLN and CLT results for a different environment, given by a family of independent simple symmetric random walks in equilibrium.

Symmetric heavily tailed random walks on Zd, d ≥ 1, are considered. Under appropriate regularity conditions on the tails of the jump distributions, global (i.e. uniform in x, t, ∣x∣ + t → ∞,) asymptotic behavior of the transition probability p(t, 0, x) is obtained. The examples indicate that the regularity conditions are essential.

Let X and Y be two simple symmetric continuous-time random walks on the vertices of the n-dimensional hypercube, Z2n. We consider the class of co-adapted couplings of these processes, and describe an intuitive coupling which is shown to be the fastest in this class.

Let X and Y be two simple symmetric continuous-time random walks on the vertices of the n-dimensional hypercube, Z 2 n . We consider the class of co-adapted couplings of these processes, and describe an intuitive coupling which is shown to be the fastest in this class.

AbstractFamously, a d-dimensional, spatially homogeneous random walk whose increments are nondegenerate, have finite second moments, and have zero mean is recurrent if d∈{1,2}, but transient if d≥3. Once spatial homogeneity is relaxed, this is no longer true. We study a family of zero-drift spatially nonhomogeneous random walks (Markov processes) whose increment covariance matrix is asymptotically constant along rays from the origin, and which, in any ambient dimension d≥2, can be adjusted so that the walk is either transient or recurrent. Natural examples are provided by random walks whose increments are supported on ellipsoids that are symmetric about the ray from the origin through the walk's current position; these elliptic random walks generalize the classical homogeneous Pearson‒Rayleigh walk (the spherical case). Our proof of the recurrence classification is based on fundamental work of Lamperti.

A neural model with N interacting neurons is considered. A firing of neuron i delays the firing times of all other neurons by the same random variable θ(i), and in isolation the firings of the neuron occur according to a renewal process with generic interarrival time Y(i). The stationary distribution of the N-vector of inhibitions at a firing time is computed, and involves waiting distributions of GI/G/1 queues and ladder height renewal processes. Further, the distribution of the period of activity of a neuron is studied for the symmetric case where θ(i) and Y(i) do not depend upon i. The tools are probabilistic and involve path decompositions, Palm theory and random walks.

A neural model with N interacting neurons is considered. A firing of neuron i delays the firing times of all other neurons by the same random variable θ(i), and in isolation the firings of the neuron occur according to a renewal process with generic interarrival time Y (i). The stationary distribution of the N-vector of inhibitions at a firing time is computed, and involves waiting distributions of GI/G/1 queues and ladder height renewal processes. Further, the distribution of the period of activity of a neuron is studied for the symmetric case where θ(i) and Y (i) do not depend upon i. The tools are probabilistic and involve path decompositions, Palm theory and random walks.

AbstractWe consider continuous-time random walks on a random locally finite subset of $$\mathbb {R}^d$$ R d with random symmetric jump probability rates. The jump range can be unbounded. We assume some second-moment conditions and that the above randomness is left invariant by the action of the group $$\mathbb {G}=\mathbb {R}^d$$ G = R d or $$\mathbb {G}=\mathbb {Z}^d$$ G = Z d . We then add a site-exclusion interaction, thus making the particle system a simple exclusion process. We show that, for almost all environments, under diffusive space–time rescaling the system exhibits a hydrodynamic limit in path space. The hydrodynamic equation is non-random and governed by the effective homogenized matrix D of the single random walk, which can be degenerate. The above result covers a very large family of models including e.g. simple exclusion processes built from random conductance models on $$\mathbb {Z}^d$$ Z d and on crystal lattices (possibly with long conductances), Mott variable range hopping, simple random walks on Delaunay triangulations, random walks on supercritical percolation clusters.

Abstract We present a reflection principle for a wide class of symmetric random motions with finite velocities. We propose a deterministic argument which is then applied to trajectories of stochastic processes. In the case of symmetric correlated random walks and the symmetric telegraph process, we provide a probabilistic result recalling the classical reflection principle for Brownian motion, but where the initial velocity has a crucial role. In the case of the telegraph process we also present some consequences which lead to further reflection-type characteristics of the motion.

We consider the dynamics of fluctuations in the quantum asymmetric simple exclusion process (Q-ASEP) with periodic boundary conditions. The Q-ASEP describes a chain of spinless fermions with random hoppings that are induced by a Markovian environment. We show that fluctuations of the fermionic degrees of freedom obey evolution equations of Lindblad type, and derive the corresponding Lindbladians. We identify the underlying algebraic structure by mapping them to non-Hermitian spin chains and demonstrate that the operator space fragments into exponentially many (in system size) sectors that are invariant under time evolution. At the level of quadratic fluctuations we consider the Lindbladian on the sectors that determine the late time dynamics for the particular case of the quantum symmetric simple exclusion process (Q-SSEP). We show that the corresponding blocks in some cases correspond to known Yang-Baxter integrable models and investigate the level-spacing statistics in others. We carry out a detailed analysis of the steady states and slow modes that govern the late time behaviour and show that the dynamics of fluctuations of observables is described in terms of closed sets of coupled linear differential-difference equations. The behaviour of the solutions to these equations is essentially diffusive but with relevant deviations, that at sufficiently late times and large distances can be described in terms of a continuum scaling limit which we construct. We numerically check the validity of this scaling limit over a significant range of time and space scales. These results are then applied to the study of operator spreading at large scales, focusing on out-of-time ordered correlators and operator entanglement.

Abstract First passage of stochastic processes under resetting has recently been an active research topic in the field of statistical physics. However, most of previous studies mainly focused on the systems with continuous time and space. In this paper, we study the effect of stochastic resetting on first passage properties of discrete-time absorbing Markov chains, described by a transition matrix $\brm{Q}$ between transient states and a transition matrix $\brm{R}$ from transient states to absorbing states. Using a renewal approach, we exactly derive the unconditional mean first passage time (MFPT) to any absorbing state, the splitting probabilities and the conditional MFPT to a specific absorbing state without hitting any other absorbing state. All the quantities can be expressed in terms of a deformed fundamental matrix $\brm{Z_{\gamma}}=\left[\brm{I}-(1-\gamma) \brm{Q} \right]^{-1}$ and $\brm{R}$, where $\brm{I}$ is the identity matrix, and $\gamma$ is the resetting probability at each time step. We further show a sufficient condition under which the unconditional MPFT can be optimized by stochastic resetting. Finally, we apply our results to two concrete examples: symmetric random walks on one-dimensional lattices with absorbing boundaries and voter model on complete graphs.

What are the possibilities of a body? This is a question that is answered best by thinking prosthetically. After all, the possibilities of a body extend beyond flesh and bone. Asked another way, one might query: what are the affective capacities of bodies—animal or otherwise? Philosophers Gilles Deleuze and Félix Guattari focus on affectivity as capacity, on what the body does or can do; thinking through Baruch Spinoza’s writing on the body, they state, “we know nothing about a body until we know what it can do, in other words, what its affects are, how they can or cannot enter into composition with other affects” (257). If bodies are defined by their affective capacities, I wonder: how can prosthetics be used to alter dominant and dominating relationships between the human and the non-human animal, particularly as these relationships bear on questions of race? In this essay, I forward a contemporary media installation, “The Slug Princess”, as a productive site for thinking through the prosthetic possibilities around issues of race, animality, and aesthetics. I contend that the Degenerate Art Ensemble’s installation works through uncommon prosthetics to activate what Deleuze and Guattari describe as becoming-animal. While animality has historically been mobilized to perpetuate Orientalist logics, I argue that DAE’s becoming-slug rethinks the capacities of the body prosthetically, and in so doing dismantles the hierarchy of the body normativity.The Degenerate Art Ensemble (DAE) is a collective of artists with international showings co-directed by Haruko Crow Nishimura, originally from Japan, and Joshua Kohl, from the United States. The ensemble is based in Seattle, Washington, USA. The group’s name is a reference to the 1937 Degenerate Art Exhibition in Munich, Germany, organized by Adolf Ziegler and the Nazi Party. The exhibition staged 650 works from what Nazi officials referred to as “art stutterers”, the pieces were confiscated from German museums and defined as works that “insult German feeling, or destroy or confuse natural form or simply reveal an absence of adequate manual and artistic skill” (Spotts 163). DAE “selected this politically charged moniker partly in response to the murder in Olympia [Washington] of an Asian American youth by neo-Nazi skinheads” (Frye). DAE’s namesake is thus an embrace of bodies and abilities deemed unworthy by systems of corrupt power. With this in mind, I argue that DAE’s work provides an opportunity to think through intersections of prostheticity, animality, and race.“The Slug Princess” is part of a larger exhibition of their work shown from 19 March to 19 June 2011 at the Frye Art Museum in Seattle. The installation is comprised of two major elements: a crocheted work and a video projection. For me, both are prosthetics.A Crocheted Prosthetic and Orientalist AnimalityThe crocheted garment is not immediately recognizable as a prosthetic. It is displayed on a mannequin that stands mostly erect. The piece, described as a headdress, is however by no means a traditional garment. Yellow spirals and topographies flow and diverge in tangled networks of yarn that sometimes converge into recognizable form. The knit headdress travels in countless directions, somehow assembling as a wearable fibrous entity that covers the mannequin from head to ground, spreading out, away, and behind the figuration of the human. In slumped orbs, green knit “cabbages’ surround the slug princess headdress, exceeding the objects they intend to represent in mass, shape, and affect. In this bustling excess of movement, the headdress hints at how it is more than a costume, but is instead a prosthetic.The video projection makes the prosthetic nature of the crocheted headdress evident. It is a looped performance of Nishimura that runs from ceiling to floor and spans the semi-enclosed space in which it is displayed. In the video, Nishimura walks, then crawls – slowly, awkwardly – through a forest. She also eats whole cabbages, supporting procedure with mouth, foot, and appendage, throwing the function of her body parts into question. The crocheted element is vital to her movement and the perception of her body’s capacities.As Nishimura becomes slug princess, the DAE begins to intervene in complex regimes of racial identification. It is imperative to note that Nishimura’s boy gets caught up in interpretive schemas of Western constructions of Asians as animals. For example, in the early diaspora in the United States, Chinese men were often identified with the figure of the rat in 19th-century political cartoons. Mel Y. Chen points to the ways in which these racialized animalities have long reinforcing the idea of the yellow peril through metaphor (Chen 110-111). These images were instrumental in conjuring fear around the powerfully dehumanizing idea that hordes of rats were infesting national purity. Such fears were significant in leading to the Chinese exclusion acts of the United States and Canada. Western tropes of Asians find traction in animal symbolism. From dragon ladies to butterflies, Asian femininity in both women and men has been captured by simultaneous notions of treachery and passivity. As Nishimura’s body is enabled by prosthetic, it is also caught in a regime of problematic signs. Animal symbolism persists throughout Asian diasporic gender construction and Western fantasies of the East. Rachel C. Lee refers to the “process whereby the human is reduced to the insect, rodent, bird, or microbe” as zoe-ification, which she illustrates as a resolute means of excluding Asian Americans from species-being (Lee Exquisite 48). DAE’s Slug Princess, I argue, joins Lee’s energies herein by providing and performing alternative modes of understanding animality.The stakes of prosthetics in becoming-animal lie in the problem of domination through definition. Orientalist animality functions to devalue Asians as animals, ultimately justifying forms of subordination and exclusion. I want to suggest that becoming-slug, as I will elaborate below, provides a mode of resisting this narrow function of defining bodies by enacting prosthetic process. In doing so, it aligns with the ways in which prosthetics redefine the points of delineation against normativity. As Margarit Shildrick illuminates, “once it is acknowledged that a human body is not a discrete entity ending at the skin, and that material technologies constantly disorder our boundaries, either through prosthetic extensions or through the internalization of mechanical parts, it is difficult to maintain that those whose bodies fail to conform to normative standards are less whole or complete than others” (24). DAE’s Slug Princess transmutates how animality functions to Orientalize Asians as the degenerate other, heightening the ways in which prosthetics can resist the racialized ideologies of normative wholeness.Why Prosthetics? Or, a Comparative Case in Aesthetic AnimalityDAE is of course not alone in their animalistic interventions. In order to isolate what I find uniquely productive about DAE’s prosthetic performance, I turn to another artistic alternative to traditional modes of Orientalist animality. Xu Bing’s performance installation “Cultural Animal” (1994) at the Han Mo Art Center in in Beijing, China can serve as a useful foil. “Cultural Animal” featured a live pig and mannequin in positions that evoked queer bestial sexuality. The pig was covered in inked nonsensical Roman letters; the full body of the mannequin was similarly tattooed in jumbled Chinese characters. The piece was a part of a larger project entitled “A Case Study of Transference”. According to Xu’s website, “the intention was both to observe the reaction of the pig toward the mannequin and produce an absurd random drama—an intention that was realized when the pig reacted to the mannequin in an aggressively sexual manner” (Xu). The photographs, which were a component of the piece, indeed evoke the difficulty of the concept of transference, imbricating species, languages, and taboos. The piece more generally enacts the unexpected excesses of performance with non-scripted bodies. The pig at times caresses the cheek of the mannequin. The sensuous experience is inked by the cultural confusion that images the seeming sensibility of each language. Amidst the movement of the pig and the rubbings of the ink, the mannequin is motionless, bearing a look of resigned openness. His eyes are closed, with a slight furrowing of the brow and calm downturned lips. The performance piece enacts crossings that reorient the historical symbolic force of racialization and animality. These forms of species and cultural miscegenation evoke for Mel Y. Chen a form of queer relationality that exemplifies “animalities that live together with race and with queerness, the animalities that we might say have crawled into the woodwork and await recognition, and, concurrently, the racialized animalities already here” (104). As such, Chen does the work of pointing out how Xu destabilizes notions of proper boundaries between human and animal, positing a different form of human-animal relationality. In short, Xu’s Cultural Animal chooses relationality. This relationality does not extend the body’s capacities. I argue that by focusing in on the pivotal nature of prosthesis, DAE’s slug activates a becoming-animal that goes beyond relationship, instead rethinking what a body can do.Becoming-Slug: Prosthetics as InterventionBy way of differentiation, how might “The Slug Princess” function beyond symbolic universalism and in excess of human-animal relations? In an effort to understand this distinction, I forward DAE’s installation as a practice of becoming-animal. Becoming-animal is a theoretical intervention in hierarchy, highlighting a minoritarian tactic to resist domination, akin to Shildrick’s description of prosthetics.DAE’s installation enacts becoming-slug, as illustrated in an elaboration of Deleuze and Guattari’s concept they argue: “Becoming-animal always involves a pack” “a multiplicity” (Deleuze and Guatttari 239). The banner of becoming-animal is “I am legion”. DAE is and are a propagation of artists working together. They enact legion. Led by a pack of collaborators, DAE engage a range of artists in continual, ongoing, and fluctuating process. Their current collaborators include (and surpass): architect/designer Alan Maskin, costume designer ALenka Loesch, dancer/singer Dohee Lee, performance artist/expressionist/songwriter/shape-shifter Okanomodé, and sound/installation artist Robb Kunz. For the broader exhibition at the Frye, they listed the biographies of fifteen artists and the names of around 200 artists. Yet, it is not the mere number of collaborators that render DAE a multiplicity – it is the collaborative excess of their process that generates potential at the intersection of performance and prosthetic. Notably, it is important that the wearable prosthetic headpiece used in “Slug Princess” was created in collaboration. “The contagion of the pack, such is the path becoming-animal takes” (Deleuze and Guattari, 243). Created by Many Greer but worn by Nishimura, it weighs on Nishimura’s body in ways that steer her performance. She is unable to stand erect as the mannequin in the exhibition. The prosthetic changes her capacities in unpredictable ways. The unexpected headdress causes her to hunch over and crawl, pushing her body into slow contact with the earth. As the flowing garment slows her forward progress, it activates new modes of movement. Snagging, and undulating, Nishimura moves slowly over the uncertain terrain of a forest. As Greer’s creation collides with Nishimura’s body and the practice of the dance, they enact becoming-slug. This is to suggest, then, following Deleuze and Guattari’s affective understanding of becoming-animal, that prosthetics have a productive role to play in disrupting normative modes of embodiment.Further, as Deleuze and Guattari indicate, becoming-animal is non-affiliative (Deleuze and Guattari 238). Becoming-animal is that which is “not content to proceed by resemblance and for which resemblance, on the contrary, would represent an obstacle or stoppage” (Deleuze and Guattari 233). Likewise, Nishimura’s becoming-slug is neither imitative (305) nor mimetic because it functions in the way of displaced doing through prosthetic process. Deleuze and Guattari describe in the example of Little Hans and his horse, becoming-animal occurs in putting one’s shoes on one’s hands to move, as a dog: “I must succeed in endowing the parts of my body with relations of speed and slowness that will make it become dog, in an original assemblage proceeding neither by resemblance nor by analogy” (258). The headdress engages an active bodily process of moving as a slug, rather than looking like a slug. Nishimura’s body begin as her body human begins, upright, but it is pulled down and made slow by the collaborative force of the wearable piece. As such, DAE enacts “affects that circulate and are transformed within the assemblage: what a horse [slug] ‘can do’” (257). This assemblage of affects pushes beyond the limited capacities of the screen, offering new productive entanglements.The Stuplime Loop as ProstheticTo the extent that conceiving of a headdress as a collaborative bodily prosthetic flows from common understandings of prosthetic, the medial interface perhaps stirs up a more foreign example of prosthesis and becoming-animal. The medial performance of DAE’s “The Slug Princess” operates through the video loop, transecting the human, animal, and technological in a way that displaces being in favor of becoming. The looping video creates a spatio-temporal contraction and elongation of the experience of time in relation to viewing. It functions as an experiential prosthetic, reworking the ability to think in a codified manner—altering the capacities of the body. Time play breaks the chronological experience of straight time and time as mastery by turning to the temporal experience as questioning normativity. Specifically, “The Slug Princess” creates productive indeterminacy through what Siane Ngai designates as “stuplimity”. Ngai’s punning contraction of stupidity and sublimity works in relation to Deleuze’s thinking on repetition and difference. Ngai poses the idea of stuplimity as beginning with “the dysphoria of shock and boredom” and culminating “in something like the ‘open feeling’ of ‘resisting being’—an indeterminate affective state that lacks the punctuating ‘point’ of individuated emotion” (284). Ngai characterizes this affecting openness and stupefying: it stops the viewer in their/her/his tracks. This importation of the affective state cannot be overcome through the exercise of reason (270). Departing from Kant’s description of the sublime, Ngai turns to the uglier, less awe-inspiring, and perhaps more debase form of aesthetic encounter. This is the collaboration of the stupid with the sublime. Stuplimity operates outside reason and sublimity but in alliance with their processes. Viewers seem to get “stuck” at “The Slug Princess”, lost in the stuplimity of the loop. Some affect of the looping videos generates not thoughtfulness or reflection, but perhaps cultural stupidity – the relative and temporary cessation or abatement of cultural logics and aesthetic valuations. The video loop comes together with the medial enactment of becoming-slug in such a manner that performs into stuplimity. Stuplimity, in this case, creates an opening of an affectively stupid or illegible (per Xu) space/time alternative being/becoming. The loop is, of course, not unique to the installation and is a common feature of museum pieces. Yet, the performance, the becoming-slug itself, creates sluggishness. Ngai posits that sluggishness works out the boredom of repetition, which I argue is created through the loop of becoming-slug. The slug princess’ slowness, played in the loop creates a “stuplimity [that] reveals the limits of our ability to comprehend a vastly extended form as totality” (271). That is, the loop, by virtue of its sluggishness, opens up becoming-animal not as a finite thing, but as an ongoing, cycling, and thoughtlessly tedious process. DAE’s installation thus demonstrates an attempt to adopt prosthetics to rethink the logics of control and power. In his writing on contemporary shifts in prosthetic function, Paul Preciado argues that digitalization is a core component of the transition from prosthetics to what emerge as “microprosthetic”, in which “power acts through molecules that incorporate themselves into our [bodies]” (78-79). I would like to consider the stuplime loops of becoming-slug to counter what Preciado describes as an “ensemble of new microprosthetic mechanisms of control of subjectivity by means of biomolecular and multimedia technical protocols” (33). Emerging in the same fashion as microproesthetics, which function as modes of control, the stuplime loops instead suspend the logics of control and power enabled by dominant modes of microprosthetic technologies. Rather than infesting one’s body with modes of control, the stuplime loops hijack the digital message and present the possibility of thinking otherwise. In her writing on queer cyborgs, Mimi Nguyen argues that “as technologies of the self, prostheses are both literal and discursive in the digital imaginary. They are a means of habitation and transformation, a humanmachine mixture engaged as a site of contest over meanings – of the self and the nonself” (373). Binaries perhaps structure a thinking between human and animal, but prosthetics as process goes beyond the idea of the cyborg as a mixture and maps a new terrain altogether.ReferencesChen, Mel Y. Animacies: Biopolitics, Racial Mattering, and Queer Affect. Durham: Duke University Press, 2012.Frye. “Degenerate Art Ensemble.” Frye Museum. 2017. <http://fryemuseum.org/exhibition/3816/>.Lee, Rachel C. The Exquisite Corpse of Asian America: Biopolitics, Biosociality, and Posthuman Ecologies. New York: New York University Press, 2014.Ngai, Sianne. Ugly Feelings. Cambridge: Harvard University Press, 2005. Nguyen, Mimi. “Queer Cyborgs and New Mutants: Race, Sexuality, and Prosthetic Sociality in Digital Space.” American Studies: An Anthology. Eds. Janice A. Radway, Kevin K. Gaines, Barry Shank, and Penny Von Eschen. Chichester: Wiley-Blackwell, 2009. 281-305.Preciado, Beatriz [Paul]. Testo Junkie: Sex, Drugs, and Biopolitis in the Pharmacopornographic Era. Trans. Bruce Benderson. New York: The Feminist Press at the City University of New York, 2013.Shildrick, Margarit. “‘Why Should Our Bodies End at the Skin?’: Embodiment, Boundaries, and Somatechnics.” Hypatia 30.1 (2015): 13-29.Spotts, Frederic. Hitler and the Power of Aesthetics. New York: Harry N. Abrams Publishers, 2003.Xu, Bing. “Cultural Animal.” 2017. <http://www.xubing.com/index.php/site/projects/year/1994/cultural_animal>.

Unlike some current discourse on automediality, this essay eschews most of the analysis concerning the adoption or modification of avatars to deliberately enhance, extend or distort the self. Rather than the automedial enabling of alternative, virtual selves modified by playful, confronting or disarming avatars we concentrate instead on emerging efforts to present the self in hyper-realist, interactive modes. In doing so we ask, what is the relationship between traumatic forms of automediation and the affective impact on and response of the audience? We argue that, while on the one hand there are promising avenues for valuable individual and social engagements with traumatic forms of automediation, there is an overwhelming predominance of suffering as a theme in such virtual depictions, comingled with uncritically asserted promises of empathy, which are problematic as the technology assumes greater mainstream uptake.As Smith and Watson note, embodiment is always a “translation” where the body is “dematerialized” in virtual representation (“Virtually” 78). Past scholarship has analysed the capacity of immersive realms, such as Second Life or online games, to highlight how users can modify their avatars in often spectacular, non-human forms. Critics of this mode of automediality note that users can adopt virtually any persona they like (racial, religious, gendered and sexual, human, animal or hybrid, and of any age), behaving as “identity tourists” while occupying virtual space or inhabiting online communities (Nakamura). Furthermore, recent work by Jaron Lanier, a key figure from the 1980s period of early Virtual Reality (VR) technology, has also explored so-called “homuncular flexibility” which describes the capacity for humans to seemingly adapt automatically to the control mechanisms of an avatar with multiple legs, other non-human appendages, or for two users to work in tandem to control a single avatar (Won et. al.). But this article is concerned less with these single or multi-player online environments and the associated concerns over modifying interactive identities. We are principally interested in other automedial modes where the “auto” of autobiography is automated via Artificial Intelligences (AIs) to convincingly mimic human discourse as narrated life-histories.We draw from case studies promoted by the 2017 season of ABC television’s flagship science program, Catalyst, which opened with semi-regular host and biological engineer Dr Jordan Nguyen, proclaiming in earnest, almost religious fervour: “I want to do something that has long been a dream. I want to create a copy of a human. An avatar. And it will have a life of its own in virtual reality.” As the camera followed Nguyen’s rapid pacing across real space he extolled: “Virtual reality, virtual human, they push the limits of the imagination and help us explore the impossible […] I want to create a virtual copy of a person. A digital addition to the family, using technology we have now.”The troubling implications of such rhetoric were stark and the next third of the program did little to allay such techno-scientific misgivings. Directed and produced by David Symonds, with Nguyen credited as co-developer and presenter, the episode “Meet the Avatars” immediately introduced scenarios where “volunteers” entered a pop-up inner city virtual lab, to experience VR for the first time. The volunteers were shown on screen subjected to a range of experimental VR environments designed to elicit fear and/or adverse and disorienting responses such as vertigo, while the presenter and researchers from Sydney University constantly smirked and laughed at their participants’ discomfort. We can only wonder what the ethics process was for both the ABC and university researchers involved in these broadcast experiments. There is little doubt that the participant/s experienced discomfort, if not distress, and that was televised to a national audience. Presenter Nguyen was also shown misleading volunteers on their way to the VR lab, when one asked “You’re not going to chuck us out of a virtual plane are you?” to which Nguyen replied “I don't know what we’re going to do yet,” when it was next shown that they immediately underwent pre-programmed VR exposure scenarios, including a fear of falling exercise from atop a city skyscraper.The sweat-inducing and heart rate-racing exposures to virtual plank walks high above a cityscape, or seeing subjects haptically viewing spiders crawl across their outstretched virtual hands, all elicited predictable responses, showcased as carnivalesque entertainment for the viewing audience. As we will see, this kind of trivialising of a virtual environment’s capacity for immersion belies the serious use of the technology in a range of treatments for posttraumatic stress disorder (see Rizzo and Koenig; Rothbaum, Rizzo and Difede).Figure 1: Nguyen and researchers enjoying themselves as their volunteers undergo VR exposure Defining AutomedialityIn their pioneering 2008 work, Automedialität: Subjektkonstitution in Schrift, Bild und neuen Medien, Jörg Dünne and Christian Moser coined the term “automediality” to problematise the production, application and distribution of autobiographic modes across various media and genres—from literary texts to audiovisual media and from traditional expression to inter/transmedia and remediated formats. The concept of automediality was deployed to counter the conventional critical exclusion of analysis of the materiality/technology used for an autobiographical purpose (Gernalzick). Dünne and Moser proffered a concept of automediality that rejects the binary division of (a) self-expression determining the mediated form or (b) (self)subjectivity being solely produced through the mediating technology. Hence, automediality has been traditionally applied to literary constructs such as autobiography and life-writing, but is now expanding into the digital domain and other “paratextual sites” (Maguire).As Nadja Gernalzick suggests, automediality should “encourage and demand not only a systematics and taxonomy of the constitution of the self in respectively genre-specific ways, but particularly also in medium-specific ways” (227). Emma Maguire has offered a succinct working definition that builds on this requirement to signal the automedial universally, noting it operates asa way of studying auto/biographical texts (of a variety of forms) that take into account how the effects of media shape the kinds of selves that can be represented, and which understands the self not as a preexisting subject that might be distilled into story form but as an entity that is brought into being through the processes of mediation.Sidonie Smith and Julia Watson point to automediality as a methodology, and in doing so emphasize how the telling or mediation of a life actually shapes the kind of story that can be told autobiographically. They state “media cannot simply be conceptualized as ‘tools’ for presenting a preexisting, essential self […] Media technologies do not just transparently present the self. They constitute and expand it” (Smith and Watson “Virtually Me” 77).This distinction is vital for understanding how automediality might be applied to self-expression in virtual domains, including the holographic avatar dreams of Nguyen throughout Catalyst. Although addressing this distinction in relation to online websites, following P. David Marshall’s description of “the proliferation of the public self”, Maguire notes:The same integration of digital spaces and platforms into daily life that is prompting the development of new tools in autobiography studies […] has also given rise to the field of persona studies, which addresses the ways in which individuals engage in practices of self-presentation in order to form commoditised identities that circulate in affective communities.For Maguire, these automedial works operate textually “to construct the authorial self or persona”.An extension to this digital, authorial construction is apparent in the exponential uptake of screen mediated prosumer generated content, whether online or theatrical (Miller). According to Gernalzick, unlike fictional drama films, screen autobiographies more directly enable “experiential temporalities”. Based on Mary Anne Doane’s promotion of the “indexicality” of film/screen representations to connote the real, Gernalzick suggests that despite semiotic theories of the index problematising realism as an index as representation, the film medium is still commonly comprehended as the “imprint of time itself”:Film and the spectator of film are said to be in a continuous present. Because the viewer is aware, however, that the images experienced in or even as presence have been made in the past, the temporality of the so-called filmic present is always ambiguous” (230).When expressed as indexical, automedial works, the intrinsic audio-visual capacities of film and video (as media) far surpass the temporal limitations of print and writing (Gernalzick, 228). One extreme example can be found in an emergent trend of “performance crime” murder and torture videos live-streamed or broadcast after the fact using mobile phone cameras and FaceBook (Bender). In essence, the political economy of the automedial ecology is important to understand in the overall context of self expression and the governance of content exhibition, access, distribution and—where relevant—interaction.So what are the implications for automedial works that employ virtual interfaces and how does this evolving medium inform both the expressive autobiographical mode and audiences subjectivities?Case StudyThe Catalyst program described above strove to shed new light on the potential for emerging technology to capture and create virtual avatars from living participants who (self-)generate autobiographical narratives interactively. Once past the initial gee-wiz journalistic evangelism of VR, the episode turned towards host Nguyen’s stated goal—using contemporary technology to create an autonomous virtual human clone. Nguyen laments that if he could create only one such avatar, his primary choice would be that of his grandfather who died when Nguyen was two years old—a desire rendered impossible. The awkward humour of the plank walk scenario sequence soon gives way as the enthusiastic Nguyen is surprised by his family’s discomfort with the idea of digitally recreating his grandfather.Nguyen next visits a Southern California digital media lab to experience the process by which 3D virtual human avatars are created. Inside a domed array of lights and cameras, in less than one second a life-size 3D avatar is recorded via 6,000 LEDs illuminating his face in 20 different combinations, with eight cameras capturing the exposures from multiple angles, all in ultra high definition. Called the Light Stage (Debevec), it is the same technology used to create a life size, virtual holocaust survivor, Pinchas Gutter (Ziv).We see Nguyen encountering a life-size, high-resolution 2D screen version of Gutter’s avatar. Standing before a microphone, Nguyen asks a series of questions about Gutter’s wartime experiences and life in the concentration camps. The responses are naturalistic and authentic, as are the pauses between questions. The high definition 4K screen is photo-realist but much more convincing in-situ (as an artifact of the Catalyst video camera recording, in some close-ups horizontal lines of transmission appear). According to the project’s curator, David Traum, the real Pinchas Gutter was recorded in 3D as a virtual holograph. He spent 25 hours providing 1,600 responses to a broad range of questions that the curator maintained covered “a lot of what people want to say” (Catalyst).Figure 2: The Museum of Jewish Heritage in Manhattan presented an installation of New Dimensions in Testimony, featuring Pinchas Gutter and Eva SchlossIt is here that the intersection between VR and auto/biography hybridise in complex and potentially difficult ways. It is where the concept of automediality may offer insight into this rapidly emerging phenomenon of creating interactive, hyperreal versions of our selves using VR. These hyperreal VR personae can be questioned and respond in real-time, where interrogators interact either as casual conversers or determined interrogators.The impact on visitors is sobering and palpable. As Nguyen relates at the end of his session, “I just want to give him a hug”. The demonstrable capacity for this avatar to engender a high degree of empathy from its automedial testimony is clear, although as we indicate below, it could simply indicate increased levels of emotion.Regardless, an ongoing concern amongst witnesses, scholars and cultural curators of memorials and museums dedicated to preserving the history of mass violence, and its associated trauma, is that once the lived experience and testimony of survivors passes with that generation the impact of the testimony diminishes (Broderick). New media modes of preserving and promulgating such knowledge in perpetuity are certainly worthy of embracing. As Stephen Smith, the executive director of the USC Shoah Foundation suggests, the technology could extendto people who have survived cancer or catastrophic hurricanes […] from the experiences of soldiers with post-traumatic stress disorder or survivors of sexual abuse, to those of presidents or great teachers. Imagine if a slave could have told her story to her grandchildren? (Ziv)Yet questions remain as to the veracity of these recorded personae. The avatars are created according to a specific agenda and the autobiographical content controlled for explicit editorial purposes. It is unclear what and why material has been excluded. If, for example, during the recorded questioning, the virtual holocaust survivor became mute at recollecting a traumatic memory, cried or sobbed uncontrollably—all natural, understandable and authentic responses given the nature of the testimony—should these genuine and spontaneous emotions be included along with various behavioural ticks such as scratching, shifting about in the seat and other naturalistic movements, to engender a more profound realism?The generation of the photorealist, mimetic avatar—remaining as an interactive persona long after the corporeal, authorial being is gone—reinforces Baudrillard’s concept of simulacra, where a clone exists devoid of its original entity and unable to challenge its automedial discourse. And what if some unscrupulous hacker managed to corrupt and subvert Gutter’s AI so that it responded antithetically to its purpose, by denying the holocaust ever happened? The ethical dilemmas of such a paradigm were explored in the dystopian 2013 film, The Congress, where Robyn Wright plays herself (and her avatar), as an out of work actor who sells off the rights to her digital self. A movie studio exploits her screen persona in perpetuity, enabling audiences to “become” and inhabit her avatar in virtual space while she is limited in the real world from undertaking certain actions due to copyright infringement. The inability of Wright to control her mimetic avatar’s discourse or action means the assumed automedial agency of her virtual self as an immortal, interactive being remains ontologically perplexing.Figure 3: Robyn Wright undergoing a full body photogrammetry to create her VR avatar in The Congress (2013)The various virtual exposures/experiences paraded throughout Catalyst’s “Meet the Avatars” paradoxically recorded and broadcast a range of troubling emotional responses to such immersion. Many participant responses suggest great caution and sensitivity be undertaken before plunging headlong into the new gold rush mentality of virtual reality, augmented reality, and AI affordances. Catalyst depicted their program subjects often responding in discomfort and distress, with some visibly overwhelmed by their encounters and left crying. There is some irony that presenter Ngyuen was himself relying on the conventions of 2D linear television journalism throughout, adopting face-to-camera address in (unconscious) automedial style to excitedly promote the assumed socio-cultural boon such automedial VR avatars will generate.Challenging AuthenticityThere are numerous ethical considerations surrounding the potential for AIs to expand beyond automedial (self-)expression towards photorealist avatars interacting outside of their pre-recorded content. When such systems evolve it may be neigh impossible to discern on screen whether the person you are conversing with is authentic or an indistinguishable, virtual doppelganger. In the future, a variant on the Turning Test may be needed to challenge and identify such hyperreal simulacra. We may be witnessing the precursor to such a dilemma playing out in the arena of audio-only podcasts, with some public intellectuals such as Sam Harris already discussing the legal and ethical problems from technology that can create audio from typed text that convincingly replicate the actual voice of a person by sampling approximately 30 minutes of their original speech (Harris). Such audio manipulation technology will soon be available to anybody with the motivation and relatively minor level of technological ability in order to assume an identity and masquerade as automediated dialogue. However, for the moment, the ability to convincingly alter a real-time computer generated video image of a person remains at the level of scientific innovation.Also of significance is the extent to which the audience reactions to such automediated expressions are indeed empathetic or simply part of the broader range of affective responses that also include direct sympathy as well as emotions such as admiration, surprise, pity, disgust and contempt (see Plantinga). There remains much rhetorical hype surrounding VR as the “ultimate empathy machine” (Milk). Yet the current use of the term “empathy” in VR, AI and automedial forms of communication seems to be principally focused on the capacity for the user-viewer to ameliorate negatively perceived emotions and experiences, whether traumatic or phobic.When considering comments about authenticity here, it is important to be aware of the occasional slippage of technological terminology into the mainstream. For example, the psychological literature does emphasise that patients respond strongly to virtual scenarios, events, and details that appear to be “authentic” (Pertaub, Slater, and Barker). Authentic in this instance implies a resemblance to a corresponding scenario/activity in the real world. This is not simply another word for photorealism, but rather it describes for instance the experimental design of one study in which virtual (AI) audience members in a virtual seminar room designed to treat public speaking anxiety were designed to exhibit “random autonomous behaviours in real-time, such as twitches, blinks, and nods, designed to encourage the illusion of life” (Kwon, Powell and Chalmers 980). The virtual humans in this study are regarded as having greater authenticity than an earlier project on social anxiety (North, North, and Coble) which did not have much visual complexity but did incorporate researcher-triggered audio clips of audience members “laughing, making comments, encouraging the speaker to speak louder or more clearly” (Kwon, Powell, and Chalmers 980). The small movements, randomly cued rather than according to a recognisable pattern, are described by the researchers as creating a sense of authenticity in the VR environment as they seem to correspond to the sorts of random minor movements that actual human audiences in a seminar can be expected to make.Nonetheless, nobody should regard an interaction with these AIs, or the avatar of Gutter, as in any way an encounter with a real person. Rather, the characteristics above function to create a disarming effect and enable the real person-viewer to willingly suspend their disbelief and enter into a pseudo-relationship with the AI; not as if it is an actual relationship, but as if it is a simulation of an actual relationship (USC). Lucy Suchman and colleagues invoke these ideas in an analysis of a YouTube video of some apparently humiliating human interactions with the MIT created AI-robot Mertz. Their analysis contends that, while it may appear on first glance that the humans’ mocking exchange with Mertz are mean-spirited, there is clearly a playfulness and willingness to engage with a form of AI that is essentially continuous with “long-standing assumptions about communication as information processing, and in the robot’s performance evidence for the limits to the mechanical reproduction of interaction as we know it through computational processes” (Suchman, Roberts, and Hird).Thus, it will be important for future work in the area of automediated testimony to consider the extent to which audiences are willing to suspend disbelief and treat the recounted traumatic experience with appropriate gravitas. These questions deserve attention, and not the kind of hype displayed by the current iteration of techno-evangelism. Indeed, some of this resurgent hype has come under scrutiny. From the perspective of VR-based tourism, Janna Thompson has recently argued that “it will never be a substitute for encounters with the real thing” (Thompson). Alyssa K. Loh, for instance, also argues that many of the negatively themed virtual experiences—such as those that drop the viewer into a scene of domestic violence or the location of a terrorist bomb attack—function not to put you in the position of the actual victim but in the position of the general category of domestic violence victim, or bomb attack victim, thus “deindividuating trauma” (Loh).Future work in this area should consider actual audience responses and rely upon mixed-methods research approaches to audience analysis. 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