Dynamics of history-dependent perceptual judgment

Abstract

Identical physical inputs do not always evoke identical percepts. To investigate the role of stimulus history in tactile perception, we designed a task in which rats had to judge each vibrissal vibration, in a long series, as strong or weak depending on its mean speed. After a low-speed stimulus (trial n − 1), rats were more likely to report the next stimulus (trial n) as strong, and after a high-speed stimulus, they were more likely to report the next stimulus as weak, a repulsive effect that did not depend on choice or reward on trial n − 1. This effect could be tracked over several preceding trials (i.e., n − 2 and earlier) and was characterized by an exponential decay function, reflecting a trial-by-trial incorporation of sensory history. Surprisingly, the influence of trial n − 1 strengthened as the time interval between n − 1 and n grew. Human subjects receiving fingertip vibrations showed these same key findings. We are able to account for the repulsive stimulus history effect, and its detailed time scale, through a single-parameter model, wherein each new stimulus gradually updates the subject’s decision criterion. This model points to mechanisms underlying how the past affects the ongoing subjective experience.

From recency to central tendency biases in working memory: a unifying network model

“…The model makes predictions as to how the pattern of errors may change when the distribution of stimuli is manipulated, either at the level of the presented stimuli or through the network dynamics. In support of this, in a recent tactile categorization study [40], where rats were trained to categorize tactile stimuli according to a boundary set by the experimenter, the authors have shown that rats set their decision boundary according to the the statistical structure of the stimulus set to which they are exposed.…”

“…Although contraction bias is robustly found in different contexts, surprisingly similar tasks, such as perceptual estimation tasks, sometimes highlight opposite effects, i.e. repulsive effects [43, 44, 40]. Sensory adaptation has long been evoked to explain such findings [45, 43, 46], mostly studied in the context of vision, and shown to underly some illusion effects.…”

Neural evidence for boundary updating as the source of the repulsive bias in classification

“…Humans and non-human animals show various forms of history bias in binary classification 17 . One frequent form of such history biases is a tendency to classify an item as the class opposite to its preceding items, dubbed repulsive bias [14][15][16][17] . For instance, we tend to classify the tree of intermediate height as 'tall' after seeing a short tree.…”

“…height. However, there is an alternative scenario, which considers the possibility that the internal class boundary adaptively shifts toward recent samples of property magnitude 14, 15,17,[25][26][27][28] (Fig. 1C).…”

Corrective feedback guides human perceptual decision-making by informing about the world state rather than rewarding its choice

“…First, we localized the trials in which a PDM episode of interest occurred (the trials of interest, toi) and stacked the trials that preceded (the retrospective block of trials, toi-1) and those that followed (the prospective block of trials, toi+1) toi. Second, we derived the two psychometric curves based on the retrospective and prospective blocks of trials, respectively, and fit the cumulative normal distribution function to these curves to estimate the point-of-subjective-inequality (PSE) measures, which have previously been used [16][17][18] and known 28 to reliably estimate the history-dependent choice biases in PDM. Thus, the PSEs of the retrospective and prospective trials quantify the choice biases that exist before and after, respectively, the PDM episode of interest occurs, with negative and positive values signifying that choices are biased to ,<#>$ and ;(<,,, respectively.…”