Perceptual history propagates down to early levels of sensory analysis

Abstract

Summary One function of perceptual systems is to construct and maintain a reliable representation of the environment. A useful strategy intrinsic to modern “Bayesian” theories of perception 1 , 2 , 3 , 4 , 5 , 6 is to take advantage of the relative stability of the input and use perceptual history (priors) to predict current perception. This strategy is efficient 1 , 2 , 3 , 4 , 5 , 6 , 7 but can lead to stimuli being biased toward perceptual history, clearly revealed in a phenomenon known as serial dependence. 8 , 9 , 10 , 11 , 12 , 13 , 14 However, it is still unclear whether serial dependence biases sensory encoding or only perceptual decisions. 15 , 16 We leveraged on the “surround tilt illusion”—where tilted flanking stimuli strongly bias perceived orientation—to measure its influence on the pattern of serial dependence, which is typically maximal for similar orientations of past and present stimuli. 7 , 10 Maximal serial dependence for a neutral stimulus preceded by an illusory one occurred when the perceived, not the physical, orientations of the two stimuli matched, suggesting that the priors biasing current perception incorporate the effect of the illusion. However, maximal serial dependence of illusory stimuli induced by neutral stimuli occurred when their physical (not perceived) orientations were matched, suggesting that priors interact with incoming sensory signals before they are biased by flanking stimuli. The evidence suggests that priors are high-level constructs incorporating contextual information, which interact directly with early sensory signals, not with highly processed perceptual representations.

Serial dependence and representational momentum in single-trial perceptual decisions

“…Our results demonstrated that SD emerges at later stages than early sensory cortices 7 , likely involving task-related processing 5 . We cannot rule out the existence of SD at multiple stages of processing, as hypothesized in previous work 26 .…”

“…Note that this conclusion refers to the source of SD. Our study does not exclude that SD ultimately leads to changes in the appearance of stimuli, i.e., that the source is post-perceptual but the site of action is perceptual 7 . Perceptual decisions 5 and higher-level cognitive biases may still propagate down to sensory cortices, directly distorting the appearance of stimuli 7 .…”

“…SD occurs mostly for weak (e.g., low contrast) and briefly presented sensory signals, and shows a broad spatial tuning (e.g., ~ 15 3 ). Recent work suggests that SD may originate beyond early sensory processing (e.g., during decision or memory processes 5 , 6 ) and acts directly on the perception of the next stimulus 7 . This phenomenon has been related to predictive processes by which an internal representation of the previous stimulus is used as a prior for current perception 7 , 8 .…”

Perceptual history acts in world-centred coordinates

“…One is that orientation signals of remembered stimuli may be reconverted back into retinotopic coordinates and projected back to V1 to interact with incoming signals. Indeed, feedback from higher areas may be one of the key mechanisms mediating serial dependence (Cicchini et al, 2021). Alternatively, even primary visual areas may display more allocentric properties than is commonly assumed.…”

“…This effect, known as serial dependence , probably reflects an optimisation strategy, where perceptual systems take advantage of temporal redundancies (the relative stability of the world) to improve signal to noise ratios, and hence efficiency (Cicchini et al, 2018). Much evidence suggests that serial dependence acts directly within perceptual circuitry, at early stages of information processing (Cicchini et al, 2021), including monaural auditory circuits (Hao Tam Ho et al, 2019) and primary visual cortex (V1) (St. John-Saaltink et al, 2016).…”