The research tackles a puzzle that has long haunted body image science. Many adolescents and women overestimate normal body sizes and pursue slenderness that falls outside healthy ranges, while some individuals with obesity underestimate their own size. This phenomenon, termed body size and shape misperception, is common across cultures and is closely linked to body dissatisfaction and eating disorders. Traditional explanations have emphasized sociocultural pressures, but a newer hypothesis proposes a perceptual mechanism: constant exposure to extreme body shapes, whether on social media, television, or magazine covers, routinely triggers visual adaptation, and repeated adaptation may permanently recalibrate what the brain accepts as normal. The critical open question was whether the aftereffect of adaptation persists long enough to matter outside the lab, because aftereffects from a single short adaptation session typically fade quickly.

To find out, the team ran a series of three experiments with young Chinese women. In the first, forty participants were split into two groups. One group spent seven consecutive days adapting to contracted, thinner-than-normal body images; the other adapted to expanded, larger-than-normal bodies. Each day, the researchers measured the participants’ perception of body normality, essentially the body size they judged to be average, both before and after the adaptation session. The results were striking. Over the week of training, the baseline judgment, measured before any daily adaptation, gradually shifted toward the adapting body shape. Women who viewed thin bodies began to perceive progressively larger figures as normal, while women who viewed expanded bodies shifted in the opposite direction. Meanwhile, the day-to-day adaptation effect itself shrank, because the baseline had already moved so far that there was little room left for further change.

The most consequential finding came from a follow-up test conducted about a month after training ended. For participants who had adapted to contracted bodies, the baseline perception of normality was still significantly shifted compared with day one, retaining roughly 58 percent of the training effect. In the expanded-body group, the retained effect was even larger, about 79 percent, although the researchers caution that fewer participants from that group completed the follow-up, so that comparison should be treated as preliminary. Either way, the message is clear: brief, repeated visual exposure to distorted bodies is sufficient to produce a perceptual bias that endures for weeks, without any feedback, instruction, or conscious effort on the part of the viewer.

The study went beyond behavior and asked what happens in the brain. Using electroencephalography, the researchers recorded event-related potentials, tiny voltage fluctuations time-locked to the presentation of body images, before and after the week of training. They focused on four well-characterized components: P1 and N1, which reflect early structural encoding of bodies in occipito-temporal cortex, likely involving the extrastriate body area; P2, associated with automatic motivated attention; and the late positive potential, or LPP, which reflects later, more controlled attentional processing. Previous work had shown that enlarged bodies reliably elicit larger N1, P2, and LPP responses than normal-weight or underweight bodies, a pattern interpreted as an implicit, stimulus-driven anti-fat bias.

After a week of adapting to thin bodies, that neural bias grew stronger. The enhanced response to expanded bodies, relative to contracted and midsize ones, became significantly more pronounced in the N1 component, and the P2 bias was also greater in the thin-adaptation group. In contrast, participants who had adapted to expanded bodies showed no comparable strengthening. Importantly, responses to non-body control images, pictures of tools, were completely unaffected, ruling out the possibility that the changes simply reflected generic differences between the two EEG sessions. The training appeared to selectively sharpen the early brain response to large body shapes, potentially laying a foundation for the negative attitudes toward larger bodies documented in earlier studies.

A skeptical reader might wonder whether the whole effect is an illusion of geometry. The stimuli were created by horizontally stretching or compressing photographs, so perhaps participants were merely adapting to wide versus narrow shapes rather than to adiposity. The researchers addressed this concern in two ways. First, a rating task showed that more than 80 percent of the stimuli were judged as manipulations of thinness or largeness rather than narrowness or wideness, indicating that the images genuinely altered perceived body fat. Second, a separate experiment tested whether the aftereffect followed the signature of low-level shape adaptation or of high-level norm recalibration. Low-level contrastive processes would sharpen the boundary between thin and large categories, steepening the psychometric function without moving its center. Recalibrative processes, by contrast, shift the entire perceptual norm. The data favored recalibration: adaptation shifted the point of subjective equality without the steepening predicted by contrastive mechanisms, and model comparisons using the Bayesian Information Criterion confirmed that the position parameter, not the slope, carried the effect.

The team then deployed a drift-diffusion model to settle a long-standing debate about whether high-level aftereffects are truly perceptual or merely decisional. In this framework, the drift rate captures how quickly sensory evidence accumulates toward a judgment, while decision boundaries and starting points capture response strategy. After adaptation to contracted bodies, the drift rate for judging a body as thin decreased significantly, meaning participants needed stronger sensory evidence to reach that conclusion. After adaptation to expanded bodies, the drift rate increased. Crucially, the decision-related parameters did not budge in any condition. The aftereffect, in other words, lives in sensory processing, not in a cautious or biased response criterion.

The third experiment brought the findings into the real world. If chronic exposure to thin bodies drives these biases, then people whose professions demand slenderness should show the strongest effects. The researchers compared professionally trained performers, dancers, models, and actresses with at least two years of formal training, against non-performer controls. Despite having a significantly lower average body mass index, the performers were more preoccupied with their appearance and less satisfied with their bodies. Their perception of body normality was significantly thinner than the average body shape of the reference volunteers, while the non-performers’ judgments matched it. Most tellingly, the performers showed a significant neural response bias to expanded bodies across all measured components, including N1 and P2, whereas the non-performers showed a bias only in the later LPP. Across all participants, the magnitude of the N1 and P2 bias correlated negatively with body mass index, and lower body appreciation, extracted through principal component analysis of the questionnaires, was associated with a stronger N1 bias.

The implications reach well beyond the laboratory. The findings support the adaptation-based theory of body size misperception, suggesting that the visual diet of thin bodies consumed daily through media and professional environments can durably recalibrate the brain’s internal norm, making normal-sized bodies look large and fueling the pursuit of unhealthy slenderness. The authors note that eating disorder patients show a distinctive adaptation profile, responding only to expanded bodies and not to contracted ones, with the degree of impairment tracking symptom severity, and that body size overestimation often persists even after successful cognitive behavioral therapy. That raises an intriguing therapeutic possibility: if passive, feedback-free exposure can shift perceptual norms in healthy women, carefully designed adaptation paradigms, perhaps to larger bodies, might one day help correct distorted body perception in clinical populations. The researchers caution that their follow-up covered only one month, that their stimulus technique, while validated, could be improved with modern computer-generated imagery, and that the neural mechanisms linking perceptual and attitudinal body image remain to be mapped with neuroimaging. Still, the core message is hard to ignore: what we look at, repeatedly and passively, quietly rewrites what we believe a body should be.

Subject of Research: Visual adaptation and its persistent effects on body size perception and neural processing

Article Title: Repeated visual adaptation induces persistent behavioral and neural biases in body size perception

Article References: Sang, X., Dong, X., & Bao, M. (2026). Repeated visual adaptation induces persistent behavioral and neural biases in body size perception. iScience, 29(11), Article 117772. https://doi.org/10.1016/j.isci.2026.117772

Image Credits: AI Generated

DOI: 10.1016/j.isci.2026.117772

Keywords: body size perception, visual adaptation, body image, eating disorders, event-related potentials, perceptual norm recalibration, thin-ideal, anti-fat bias, drift-diffusion model, body dissatisfaction, media exposure, neuroscience

The theoretical backdrop for the work is the increasingly popular Bayesian account of serial dependence. According to this framework, the brain behaves like an intuitive statistician, combining noisy sensory evidence with expectations derived from recent experience to produce decisions that are optimal under uncertainty. When the current stimulus is encoded poorly, its internal representation is noisy, and the perceptual system should lean more heavily on the previous stimulus, producing stronger attractive biases. Conversely, when the previous stimulus, often called the inducer, is itself noisy, its influence on the current decision should weaken because a unreliable source of prior information deserves less weight. This elegant logic has generated a large body of findings, mostly documenting attractive biases in tasks such as orientation and face estimation. Yet the framework makes a prediction that has been far less explored: in some tasks, the strategy that actually minimizes error is not attraction but repulsion, and uncertainty should then modulate repulsive biases in predictable ways.

Yildirim and Boduroglu designed an experiment precisely to test that prediction. Participants viewed three tilted gratings in rapid succession, each flashed for roughly 83 milliseconds, and later reported the orientation of each one from memory. The critical manipulation lay in the timing. The first two targets, T1 and T2, were separated by either three or seven intervening stimuli, while the third target, T3, always followed T2 at a lag of seven. At the shorter lag, T2 fell inside the temporal window of the well-known attentional blink, the brief period after detecting one target during which attentional resources for the next are depleted. As a result, participants’ representations of T2 were measurably worse at Lag 3 than at Lag 7, as indexed by larger absolute estimation errors and lower precision. This created a natural experiment in representational noise: the same stimulus, T2, sometimes served as a well-encoded target and sometimes as a degraded one, and in both cases it also acted as the inducer for the subsequent report of T3.

The results overturned a straightforward reading of the Bayesian account. When T2’s representation was noisier, produced by the attentional blink at the short lag, the repulsive serial bias away from T1 actually grew stronger, not weaker. Reduced attentional resources amplified the tendency for participants’ estimates of T2 to be pushed away from the orientation they had just seen on T1. This is the first demonstration, the authors report, that diminished attention increases repulsive serial bias in working memory. In other words, when the current representation is unreliable, the system does not simply lean harder on the past; instead, in this task regime, it actively differentiates the present from the past, as if exaggerating the contrast between the two to keep them from being confused.

Equally striking was what did not change. The noisiness of the inducer, that is, the fidelity of T2, had no measurable effect on the bias observed in estimates of T3. Whether T2 had been encoded under the attentional blink or with full attentional resources, the repulsive pull of T2 on T3 estimates remained statistically indistinguishable. Under a strict Bayesian reading, a degraded inducer should contribute a weaker prior and therefore a smaller bias. The absence of such modulation suggests that the brain may treat the stored memory trace of a stimulus as a fixed reference point for differentiation, regardless of how faithfully that stimulus was originally captured, or that the adaptive mechanism at work here is not the classic Bayesian weighting scheme at all.

Perhaps the most intriguing findings concern the temporal reach of the repulsive effect. Serial dependence is usually studied between adjacent items, and many researchers have assumed that its influence decays rapidly with intervening stimuli. But in this experiment, estimates of T3 were repelled not only by T2 but also by T1, an item separated from T3 by a lag of ten stimuli in the rapid stream. The bias therefore extended well beyond the immediate perceptual history, implying that multiple past representations can coexist in working memory and each exert a distinct repulsive influence on a current report. This long-range repulsion is difficult to reconcile with simple low-level adaptation accounts, in which sensory neurons tuned to the previous orientation become fatigued and shift subsequent percepts away, because such aftereffects are typically short-lived and confined to the immediately preceding stimulus.

The study also uncovered evidence of repulsion operating in the opposite direction of time. Estimates of T2 were pushed away from the orientation of T3, the stimulus that followed it. Since T3 had not yet been presented when T2 appeared, this backward bias could not reflect perception at encoding. Instead, the authors argue, it emerged during the maintenance period, while T2’s representation was being held in working memory and before T3’s report was required. This implies that repulsive differentiation is an active, ongoing computation performed on stored representations rather than a passive residue of earlier sensory processing. When a new item enters working memory, existing representations appear to be reorganized to maximize their separation from the newcomer, a form of online uncertainty minimization that unfolds during the retention interval itself.

Taken together, these findings complicate the popular narrative that serial dependence is a single, attractively inclined mechanism serving perceptual stability. The authors conclude that the pattern they observed reflects adaptive uncertainty minimization in working memory that goes beyond standard Bayesian accounts of serial dependence. When a target representation is noisy, the optimal strategy for distinguishing successive items in this task is to push them apart, and the visual system appears to implement exactly that strategy, amplifying repulsion under attentional deprivation. At the same time, the insensitivity of downstream biases to inducer fidelity, the long-range influence of T1 on T3, and the backward repulsion from T3 onto T2 collectively suggest that the underlying mechanism is more like an active separation process operating across the entire contents of working memory than a passive weighting of previous percepts as priors.

The work, which was supported by the Scientific and Technological Research Council of Turkey through a 1001 program grant and doctoral and international fellowships to the first author, carries implications well beyond the laboratory. Visual working memory underlies everyday activities as varied as navigating a crowded street, comparing two paint swatches, or tracking a moving vehicle through traffic, and all of these depend on keeping successive percepts distinct. The discovery that attentional lapses strengthen the active separation of memories offers a new lens on the errors people make under cognitive load, and it may inform models of perceptual decision making, visual search, and even clinical conditions characterized by attentional dysfunction. For now, the study stands as a vivid reminder that memory is not a passive recording but a dynamic negotiation between past and present, one in which the brain sometimes decides that the best way to remember what it just saw is to remember it as deliberately different from what came before.

Subject of Research: Repulsive serial dependence in visual working memory and how target fidelity shapes serial biases

Article Title: Repulsive serial dependence in visual working memory modulated by target fidelity

Article References: Yildirim, B., & Boduroglu, A. (2026). Repulsive serial dependence in visual working memory modulated by target fidelity. BMC Biology. https://doi.org/10.1186/s12915-026-02739-9

Image Credits: AI Generated

DOI: 10.1186/s12915-026-02739-9

Keywords: visual working memory, serial dependence, serial bias, attentional blink, orientation estimation, Bayesian inference, perceptual decision making, attention, visual adaptation, working memory maintenance, repulsive bias, target fidelity