High-level Aftereffects Research Articles

(Don't) look where you are going: Evidence for a travel direction signal in humans that is independent of head direction.

We often assume that travel direction is redundant with head direction, but from first principles, these two factors provide differing spatial information. Although head direction has been found to be a fundamental component of human navigation, it is unclear how self-motion signals for travel direction contribute to forming a travel trajectory. Employing a novel motion adaptation paradigm from visual neuroscience designed to preclude a contribution of head direction, we found high-level aftereffects of perceived travel direction, indicating that travel direction is a fundamental component of human navigation. Interestingly, we discovered a higher frequency of reporting perceived travel toward the adapted direction compared to a no-adapt control-an aftereffect that runs contrary to low-level motion aftereffects. This travel aftereffect was maintained after controlling for possible response biases and approaching effects, and it scaled with adaptation duration. These findings demonstrate the first evidence of how a pure travel direction signal might be represented in humans, independent of head direction. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Aftereffects, High-Levelism and Gestalt Properties

AbstractAccording to high-levelism, one can perceptually be aware of high-level properties such as natural kind properties. Against high-levelism, the Gestalt proposal suggests that instead of high-level properties, one can have a perceptual experience as of Gestalt properties, i.e., determinables of determinate low-level properties. When one looks at a bird, the high-levelist argues that one can perceive the property of being a bird, and the proponent of the Gestalt proposal argues that one first perceives the property of having the bird Gestalt (shared by all and only birds) and only post-perceptually recognizes that it is a bird. In the present study, to resolve the dispute between high-levelism and the Gestalt proposal, I aim to test their abilities to explain the attribution of multiple perceptible properties to the same object by making use of various empirical studies on high-level aftereffects. I conclude that the Gestalt proposal fails the test and hence shall not be a viable alternative to high-levelism.

High-level aftereffects reveal the role of statistical features in visual shape encoding

Visual shape perception is central to many everyday tasks, from object recognition to grasping and handling tools.1,2,3,4,5,6,7,8,9,10 Yet how shape is encoded in the visual system remains poorly understood. Here, we probed shape representations using visual aftereffects-perceptual distortions that occur following extended exposure to a stimulus.11,12,13,14,15,16,17 Such effects are thought to be caused by adaptation in neural populations that encode both simple, low-level stimulus characteristics17,18,19,20 and more abstract, high-level object features.21,22,23 To tease these two contributions apart, we used machine-learning methods to synthesize novel shapes in a multidimensional shape space, derived from a large database of natural shapes.24 Stimuli were carefully selected such that low-level and high-level adaptation models made distinct predictions about the shapes that observers would perceive following adaptation. We found that adaptation along vector trajectories in the high-level shape space predicted shape aftereffects better than simple low-level processes. Our findings reveal the central role of high-level statistical features in the visual representation of shape. The findings also hint that human vision is attuned to the distribution of shapes experienced in the natural environment.

Visual adaptation to non-face animate objects elicits temporally robust high-level aftereffects

Visual adaptation to non-face animate objects elicits temporally robust high-level aftereffects

After-effects and the reach of perceptual content

In this paper, I discuss the use of after-effects as a criterion for showing that we can perceive high-level properties. According to this criterion, if a high-level property (for example, an emotional expression) is susceptible to after-effects, this suggests that the property can be perceived, rather than cognized. The defenders of the criterion claim that, since after-effects are also present for low-level, uncontroversially perceptual properties (such as orientation), we can safely infer that high-level after-effects are perceptual as well. The critics of the criterion, on the other hand, assimilate it to superficially similar effects in cognition (such as decision biases) and argue that the after-effect criterion is a cognitive phenomenon rather than a perceptual one, and that as a result it is not a reliable guide for exploring the contents of perception. I argue against both of these views and show that high-level after-effects cannot be identified either with low-level after-effects or with cognitive biases. I suggest an intermediate position: high-level after-effects are not cognitive, but they are nonetheless not a good criterion for exploring the contents of perception.

Pupil size is sensitive to dynamic change in scene layout properties

Previously we observed that pupil size is modulated by scene layout properties: smaller when viewing far or open scenes. Here we investigate whether changing direction of these properties, in addition to their static value, will also affect pupil size, by comparing pupillary response to otherwise identical scenes after exposure to scenes of different depths. 10 naive volunteers were instructed to free-view a series of 479 color video clips (mean duration ~8.57 s) in random order, while binocular pupil size was recorded using Eyelink 1000 eyetracker. All clips were extracted from documentary movies depicting natural or man-made sceneries, and were preprocessed to have roughly matched mean luminance and RMS contrast in each frame. Dominant depth of the scene in the clips was continuously rated by another group of 10 observers in separate sessions. Trials were sorted according to whether depth rating of preceding clip (adaptor) was farther, similar (served as baseline), or nearer compared with current clip (probe). Event-related pupil response time-locked to video onset was constructed for clips with at least one trial in all three conditions, and averaged across clips. When adaptor was farther, pupil size was significantly larger than baseline condition starting from as early as 280 ms, as if the probe was perceived nearer. The opposite was true when adapted to nearer scenes. Notably, larger difference in depth between adaptor and probe was significantly correlated with greater change in pupil size. Near reflex couldn't explain the result because it would predict opposite trend. In conclusion, the result suggests that pupil response is not only modulated by static value of scene layout properties, but also sensitive to their dynamic changes, probably due to high-level aftereffect in scene perception. Meeting abstract presented at VSS 2017

Duration Aftereffect Depends on the Duration of Adaptation

It has been widely demonstrated that a prolonged adaptation to a relatively long or short stimulus leads to a robust repulsive duration aftereffect. However, little is known about the rapid adaptation to stimulus duration. In this study, we investigated whether the duration aftereffect could also be induced by short-term adaptation to stimuli of both sub- and supra-second durations. To control for the internal reference for duration judgment, participants were adapted to a stimulus of medium duration, and then tested with both longer and shorter stimuli. We found that the duration aftereffect was only observed after long-term adaptation to stimuli of both sub- and supra-second durations, which suggests that the exposure time to the adaptor is a fundamental factor in determining the duration aftereffect. Our findings offer further evidence of the duration aftereffect, which in this study was dissociated from the anchor effect and high-level aftereffects.

Neural model for multi-stability in visual action recognition

The visual perception of body movements shows interesting dynamical properties. Biological motion perception can show perceptual multi-stability with respect to the perceived walking direction [1]. In addition, body motion perception is subject to adaptation, as is demonstrated by the existence of high-level after-effects and of fMRI repetition suppression in relevant areas. Existing neural models for action recognition do not account for these phenomena. We present neurodynamical model that reproduces these phenomena, and which allows to study the interplay between multi-stability, adaptation and intrinsic fluctuations in body motion perception.

Heads First: Visual Aftereffects Reveal Hierarchical Integration of Cues to Social Attention.

Determining where another person is attending is an important skill for social interaction that relies on various visual cues, including the turning direction of the head and body. This study reports a novel high-level visual aftereffect that addresses the important question of how these sources of information are combined in gauging social attention. We show that adapting to images of heads turned 25° to the right or left produces a perceptual bias in judging the turning direction of subsequently presented bodies. In contrast, little to no change in the judgment of head orientation occurs after adapting to extremely oriented bodies. The unidirectional nature of the aftereffect suggests that cues from the human body signaling social attention are combined in a hierarchical fashion and is consistent with evidence from single-cell recording studies in nonhuman primates showing that information about head orientation can override information about body posture when both are visible.

Are high-level aftereffects perceptual?

Imagineanexperimentinwhichyoushowsomeonepicturesofacomputer-generatedface displaying random expressions, rang-ing from happy, through neutral, to sad.You tell the participant that she must clas-sify each picture as being either “happy”or “sad,” and you note the point onthe expression continuum at which sheswitches from mostly-“happy” classifica-tions to mostly-“sad.” Then, you ask herto repeat the task, but between each pic-ture you have her feel, with her hands butout of sight, the contours of a smiling facemask. You find that her category bound-ary has shifted: she now classifies more ofthe pictures as “sad.” This result (reportedby Matsumiya, 2013)isanexampleofan aftereffect, in which adaptation to oneinput (the mask) has altered responsesto subsequent inputs (the images). It is“high-level” in the sense that the adaptingand test stimuli have little overlap in theirinitial sensory encoding (they are pre-sentedinseparatemodalities).Thereareatleast two ways to interpret this finding.

Multi-level visual adaptation: Dissociating curvature and facial-expression aftereffects produced by the same adapting stimuli

Adaptation aftereffects offer a critical window onto sensory processing in the brain. However, such sensory processing is hierarchical, progressing from the extraction of simple features to the representation of complex patterns. The way that adaptation depends on coordinated changes across different levels of the hierarchy has been studied. However, when a given adapting stimulus produces both a low- and a high-level aftereffect, it remains unclear whether the high-level aftereffect is a passive reflection of low-level adaptation, or whether it is generated, at least partially, de novo in high-level areas. We assembled the two key ingredients needed for investigating this question psychophysically. One ingredient involves perceptual tasks that depend rather exclusively on low or high levels of processing, and yet involve partially identical stimuli that inspire cross-level adaptation. For this, we considered the discrimination of curvature or facial expression using curves or cartoon faces. The other ingredient is spatial or temporal stimulus manipulations that limit adaptation to either low or high levels. For this, we used crowding and brief presentations. We found that crowding an adapting curve with flanking curves reduces the curvature aftereffect much more than the facial-expression aftereffect, and vice versa for crowding the adapting face with flanking faces. Additionally, reducing adaptation time to a cartoon face diminishes the curvature aftereffect more drastically than the facial-expression aftereffect. These results suggest that high-level aftereffects, even when generated by a low-level adaptor, are not completely inherited from lower levels, and offer a window into the determining factors.

Not All High-Level Aftereffects are Equal (And Perhaps None is Opponent Coded)

Not All High-Level Aftereffects are Equal (And Perhaps None is Opponent Coded)

Race-specific norms for coding face identity and a functional role for norms

Models of face perception often adopt a framework in which faces are represented as points or vectors in a multidimensional space, relative to the average face that serves as a norm for encoding. Since faces are very similar in their configuration and share many visual properties, they could be encoded in one common space against one norm. However, certain face properties may result in grouping and "subclassification" of similar faces. We studied the processing of faces of different races, using high-level aftereffects, where exposure to one face systematically distorts the perception of a subsequently viewed face toward the "opposite" identity in face space. We measured identity aftereffects for adapt-test pairs that were opposite relative to race-specific (Asian and Caucasian) averages and pairs that were opposite relative to a "generic" average (both races morphed together). Aftereffects were larger for race-specific compared to mixed-race adapt-test pairs. These results suggest that race-specific norms are used to code identity because aftereffects are generally larger for adapt-test pairs drawn from trajectories passing through the norm (opposite pairs) than for those that do not. We also found that identification thresholds were lower when targets were distributed around race-specific averages than around the mixed-race average, suggesting that norm-based face encoding may play a functional role in facilitating identity discrimination.

High-level adaptation aftereffects for novel objects: The role of pre-existing representations

Recent perceptual experience can strongly influence the way in which ambiguous stimuli are interpreted and categorized. A well known example is the phenomenon of adaptation aftereffects that occurs when prolonged exposure to a clear, prototypical image induce a repulsive bias in the perception of a subsequently presented ambiguous stimulus. When an ambiguous image is used as adapter, however, a facilitatory, attractive effect can be observed (priming effect). In this study, the role of a pre-existing representation in the induction of the perceptual effect was investigated, with the use of novel, unfamiliar objects (Greebles). The results of two experiments indicate that a pre-existing representation is necessary for aftereffects to be observed, but only when the contribution of low-level adaptation is controlled for. Increased familiarity with the stimuli is able to restore the repulsive effect, as indicated by a third experiment. The priming effect found for ambiguous adapters, on the other hand, seems not to be influenced by a previously stored memory representation.

Voice aftereffects of adaptation to speaker identity

While adaptation to complex auditory stimuli has traditionally been reported for linguistic properties of speech, the present study demonstrates non-linguistic high-level aftereffects in the perception of voice identity, following adaptation to voices or faces of personally familiar speakers. In Exp. 1, prolonged exposure to speaker A′s voice biased the perception of identity-ambiguous voice morphs between speakers A and B towards speaker B (and vice versa). Significantly biased voice identity perception was also observed in Exp. 2 when adaptors were videos of speakers’ silently articulating faces, although effects were reduced in magnitude relative to those seen in Exp. 1. By contrast, adaptation to an unrelated speaker C elicited an intermediate proportion of speaker A identifications in both experiments. While crossmodal aftereffects on auditory identification ( Exp. 2) dissipated rapidly, unimodal aftereffects ( Exp. 1) were still measurable a few minutes after adaptation. These novel findings suggest contrastive coding of voice identity in long-term memory, with at least two perceptual mechanisms of voice identity adaptation: one related to auditory coding of voice characteristics, and another related to multimodal coding of familiar speaker identity.

High-level after-effects in the recognition of dynamic facial expressions

High-level after-effects in the recognition of dynamic facial expressions

High-level aftereffects to natural scenes

High-level aftereffects to natural scenes

Simple stimulus metrics vs. Gestalt in high-level aftereffects

Simple stimulus metrics vs. Gestalt in high-level aftereffects

The Influence of a Low-Level Color or Figure Adaptation on a High-Level Face Perception

Visual adaptation is a universal phenomenon associated with human visual system. This adaptation affects not only the perception of low-level visual systems processing color, motion, and orientation, but also the perception of high-level visual systems processing complex visual patterns, such as facial identity and expression. Although it remains unclear for the mutual interaction mechanism between systems at different levels, this issue is the key to understand the hierarchical neural coding and computation mechanism. Thus, we examined whether the low-level adaptation influences on the high-level aftereffect by means of cross-level adaptation paradigm (i.e. color, figure adaptation versus facial identity adaptation). We measured the identity aftereffects within the real face test images on real face, color chip and figure adapting conditions. The cross-level mutual influence was evaluated by the aftereffect size among different adapting conditions. The results suggest that the adaptation to color and figure contributes to the high-level facial identity aftereffect. Besides, the real face adaptation obtained the significantly stronger aftereffect than the color chip or the figure adaptation. Our results reveal the possibility of cross-level adaptation propagation and implicitly indicate a high-level holistic facial neural representation. Based on these results, we discussed the theoretical implication of cross-level adaptation propagation for understanding the hierarchical sensory neural systems.

High-level aftereffects to global scene properties.

Adaptation is ubiquitous in the human visual system, allowing recalibration to the statistical regularities of its input. Previous work has shown that global scene properties such as openness and mean depth are informative dimensions of natural scene variation useful for human and machine scene categorization (Greene & Oliva, 2009b; Oliva & Torralba, 2001). A visual system that rapidly categorizes scenes using such statistical regularities should be continuously updated, and therefore is prone to adaptation along these dimensions. Using a rapid serial visual presentation paradigm, we show aftereffects to several global scene properties (magnitude 8-21%). In addition, aftereffects were preserved when the test image was presented 10 degrees away from the adapted location, suggesting that the origin of these aftereffects is not solely due to low-level adaptation. We show systematic modulation of observers' basic-level scene categorization performances after adapting to a global property, suggesting a strong representational role of global properties in rapid scene categorization.