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This article reviews theoretical and empirical arguments for and against various theories that explain the classic Ponzo illusion and its variants from two different viewpoints concerning the role of perceived depth in size distortions. The first viewpoint argues that all Ponzo-like illusions are driven by perceived depth. The second viewpoint argues that the classic Ponzo illusion is unrelated to depth perception. This review will give special focus to the first viewpoint and consists of three sections. In the first section, the role of the number of pictorial depth cues and previous experience in the strength of all Ponzo-like illusions are discussed. In the second section, we contrast the first viewpoint against the theories that explain the classic Ponzo illusion with mechanisms that are unrelated to depth perception. In the last section, we propose a Bayesian-motivated reconceptualization of Richard Gregory's misapplied size constancy theory that explains Ponzo-variant illusions in terms of prior information and prediction errors. The new account explains why some studies have provided inconsistent evidence for misapplied size constancy theory.

Flexibility and robustness of multisensory temporal recalibration is paramount for maintaining perceptual constancy of the surrounding natural world. Different environments impart various impediments, distances and routes that alter the propagation times of sight and sound cues comprising a multimodal event. One’s ability to rapidly calibrate and account for these external variations allows for maintained perception of synchrony which is crucial for coherent and consistent perception. The two common paradigms used to compare precision of temporal processing between experimental and control groups, the simultaneity judgment (SJ) and temporal order judgment (TOJ) tasks, often use supra-threshold stimuli. However, few studies have specifically examined the effects of normalizing stimulus intensities to participant’s unisensory detection thresholds. The current project presented multiple combinations of auditory and visual stimulus intensity levels, based on individual detection thresholds, during a TOJ and a SJ task. While no effect of stimulus intensity was found on temporal sensitivity or perceived temporal synchrony, there was a significant difference in point of subjective simultaneity (PSS) measures between tasks. In addition, PSS estimates were audio-leading, rather than visual-leading as previously reported, suggesting that exposure to the particular combinations of stimulus intensity levels used influenced temporal synchrony perception. Overall, these results support the use of supra-threshold stimuli in TOJ and SJ tasks as a way of minimizing the confound from differences in unisensory processing.

Although researchers have debated whether a core deficit of nonsymbolic representation of magnitude underlies developmental dyscalculia (DD), research has mostly focused on numerosity processing. We probed the possibility of a general magnitude deficit in individuals with DD and asked whether sensitivity to size varied in contexts of depth ordering and size constancy. We measured full psychometric functions in size-discrimination tasks in 12 participants with DD and 13 control participants. Results showed that although people with DD exhibited veridical perceived magnitude, their sensitivity to size was clearly impaired. In contrast, when objects were embedded in depth cues allowing size-constancy computations, participants with DD demonstrated typical sensitivity to size. These results demonstrate a deficit in the perceptual resolutions of magnitude in DD. At the same time, the finding of an intact size constancy suggests that when magnitude perception is facilitated by implicit mandatory computations of size constancy, this deficit is no longer evident.

Humans and animals rely on accurate object size perception to guide behavior. Object size is judged from visual input, but the relationship between an object's retinal size and its real-world size varies with distance. Humans perceive object sizes to be relatively constant when retinal size changes. Such size constancy compensates for the variable relationship between retinal size and real-world size, using the context of recent retinal sizes of the same object to bias perception towards its likely real-world size. We therefore hypothesized that object size perception may be affected by the range of recently viewed object sizes, attracting perceived object sizes towards recently viewed sizes. We demonstrate two systematic biases: a central tendency attracting perceived size towards the average size across all trials, and a serial dependence attracting perceived size towards the size presented on the previous trial. We recently described topographic object size maps in the human parietal cortex. We therefore hypothesized that neural representations of object size here would be attracted towards recently viewed sizes. We used ultra-high-field (7T) functional MRI and population receptive field modeling to compare object size representations measured with small (0.05–1.4°diameter) and large objects sizes (0.1–2.8°). We found that parietal object size preferences and tuning widths follow this presented range, but change less than presented object sizes. Therefore, perception and neural representation of object size are attracted towards recently viewed sizes. This context-dependent object size representation reveals effects on neural response preferences that may underlie context dependence of object size perception.

Previous research has revealed changes in the perception of objects due to changes of object-oriented actions. In present study, we varied the arm and finger postures in the context of a virtual reaching and grasping task and tested whether this manipulation can simultaneously affect the perceived size and distance of external objects. Participants manually controlled visual cursors, aiming at reaching and enclosing a distant target object, and judged the size and distance of this object. We observed that a visual–proprioceptive discrepancy introduced during the reaching part of the action simultaneously affected the judgments of target distance and of target size (Experiment 1). A related variation applied to the grasping part of the action affected the judgments of size, but not of distance of the target (Experiment 2). These results indicate that perceptual effects observed in the context of actions can directly arise through sensory integration of multimodal redundant signals and indirectly through perceptual constancy mechanisms. Supplementary Information The online version contains supplementary material available at 10.3758/s13423-021-01915-y.

We assessed the contribution of binocular disparity and the pictorial cues of linear perspective, texture, and scene clutter to the perception of distance in consumer virtual reality. As additional cues are made available, distance perception is predicted to improve, as measured by a reduction in systematic bias, and an increase in precision. We assessed (1) whether space is nonlinearly distorted; (2) the degree of size constancy across changes in distance; and (3) the weighting of pictorial versus binocular cues in VR. In the first task, participants positioned two spheres so as to divide the egocentric distance to a reference stimulus (presented between 3 and 11 m) into three equal thirds. In the second and third tasks, participants set the size of a sphere, presented at the same distances and at eye-height, to match that of a hand-held football. Each task was performed in four environments varying in the available cues. We measured accuracy by identifying systematic biases in responses and precision as the standard deviation of these responses. While there was no evidence of nonlinear compression of space, participants did tend to underestimate distance linearly, but this bias was reduced with the addition of each cue. The addition of binocular cues, when rich pictorial cues were already available, reduced both the bias and variability of estimates. These results show that linear perspective and binocular cues, in particular, improve the accuracy and precision of distance estimates in virtual reality across a range of distances typical of many indoor environments.

Perceptual constancy, often defined as the perception of stable features under changing conditions, goes hand in hand with variation in how things look. A white wall in the orange afternoon sun still looks white, though its whiteness looks different compared with the same wall in the noon sun. Historically, this variation has often been explained in terms of our experience of “merely sensory” or subjective properties – an approach at odds with the fact that the variation does track objective features of the perceptual situation, such as illumination (in the case of colour constancy). One approach, becoming more common, is to account for the variation in terms of further “dimensions” to perceptual experience. Especially in colour perception, this is a natural thought to have but the idea is often left vague. In this paper I argue that the “dimensional” strategy has problems of its own, but is useful in drawing out some interesting complications in the way perceptual experience is structured. Specifically, the structure of “constancy spaces” brings out the different ways in which there is stability and instability in the experience of constancy, without the need for novel or merely subjective features. Instability arises in a contingent structural feature of perceptual experience.

Color constancy is a prime example of a perceptual constancy, giving stability to mental representations of objects in an unstable world. Yet color constancy is highly variable, depending on the illumination, the object and its context, and the viewer. Color constancy is particularly challenged by artificial lights that differ from the natural illuminations under which human vision evolved. The rapid developments in solid-state lighting technologies revive the need to scrutinise the limits of color constancy, to understand whether and how it is optimised for natural illuminations, and, in turn, to optimise novel lighting technologies for human color perception. For these goals, a deeper collaboration between the disciplines of human vision science and color science is needed.

It is still unclear whether size constancy is an innate ability or whether it develops with age. As many developmental studies are limited to the child’s comprehension of the task instructions, here, an implicit measure of perceived size, namely, simple manual reaction time (RT), was opted for based on the assumption that perceptually bigger objects generate faster detection times. We examined size constancy in children (from 5 to 14 years of age) and adults using a simple RT approach. Participants were presented with pictures of tennis balls on a screen that was physically moved to two viewing distances. Visual stimuli were adjusted in physical size in order to subtend the same visual angle across distances, determining two conditions: a small-near tennis ball vs. a big-far tennis ball. Thanks to size constancy, the two tennis balls were perceived as different even though they were of equal size on the retina. Stimuli were also matched in terms of luminance. Participants were asked to react as fast as possible to the onset of the stimuli. The results show that the RTs reflected the perceived rather than the retinal size of the stimuli across the different age groups, such that participants responded faster to stimuli that were perceived as bigger than those perceived as smaller. Hence, these findings are consistent with the idea that size constancy is already present in early childhood, at least from the age of five, and does not require extensive visual learning.

Corrections applied by the visual system, like size constancy, provide us with a coherent and stable perspective from ever-changing retinal images. In the present experiment we investigated how willing adults are to examine their own vision as if it were an uncorrected 2D image, much like a photograph. We showed adult participants two lines on a wall, both of which were the same length but one was closer to the participant and hence appeared visually longer. Despite the instruction to base their judgements on appearance specifically, approximately half of the participants judged the lines to appear the same. When they took a photo of the lines and were asked how long they appeared in the image their responses shifted; now the closer line appeared longer. However, when they were asked again about their own view they reverted to their original response. These results suggest that many adults are resistant to imagining their own vision as if it were a flat image. We also place these results within the context of recent views on visual perspective-taking.

The perception of sensory events can be suppressed or enhanced by the surrounding spatial and temporal context in ways that help in detecting novel objects and establishing perceptual constancy. In the auditory system, the phenomenon known as auditory enhancement reflects a general principle of contrast enhancement, where a target sound embedded within a background sound becomes perceptually more salient if the background is presented first by itself. This effect is highly robust, producing an effective enhancement of the target of between 5 and 25 dB (more than two orders of magnitude in intensity), depending on the task. Despite their ubiquity in vision, neural correlates of auditory contrast enhancement have yet to be identified in humans. Here we used the auditory steady-state response to probe the neural response to a target sound under conditions of enhancement. The probe was simultaneously modulated in amplitude with two modulation frequencies, to distinguish cortical from subcortical contributions to this phenomenon. We found robust auditory cortical, but not subcortical, enhancement that correlates with behavior and is consistent with an early theoretical model that postulates neural adaptation of inhibition. Our findings provide empirical support for a previously unverified theory of auditory enhancement and point to new approaches for improving sensory prostheses for hearing loss, such as hearing aids and cochlear implants.Significance StatementA target sound embedded within a background sound becomes perceptually more salient if the background is presented first by itself. This phenomenon, where the target “pops out”, is known as auditory enhancement. It reflects a general principle of contrast enhancement, and helps in the detection of new acoustic events in the environment and in establishing the perceptual constancy of speech and other biologically relevant sounds under varying acoustic conditions. We use EEG in humans to reveal a cortical correlate of this perceptual phenomenon that provides empirical support for a longstanding but previously unverified theoretical account.

Since Kepler (1604) and Descartes (1637), it has been suggested that ‘vergence’ (the angular rotation of the eyes) plays a key role in size constancy. However, this has never been tested divorced from confounding cues such as changes in the retinal image. In our experiment, participants viewed a target which grew or shrank in size over 5 s. At the same time, the fixation distance specified by vergence was reduced from 50 to 25 cm. The question was whether this change in vergence affected the participants’ judgements of whether the target grew or shrank in size? We found no evidence of any effect, and therefore no evidence that eye movements affect perceived size. If this is correct, then our finding has three implications. First, perceived size is much more reliant on cognitive influences than previously thought. This is consistent with the argument that visual scale is purely cognitive in nature (Linton, 2017, 2018). Second, it leads us to question whether the vergence modulation of V1 contributes to size constancy. Third, given the interaction between vergence, proprioception, and the retinal image in the Taylor illusion, it leads us to ask whether this cognitive approach could also be applied to multisensory integration.

Previous studies have shown that people are good at rapidly estimating ensemble summary statistics, such as the mean size of multiple objects. In the present study, we tested whether these average estimates are based on "raw" retinal representations (proximal sizes) or on how items should appear based on context, such as the viewing distance (distal sizes). In our experiments, observers adjusted the mean size of multiple objects presented at various apparent distances through a stereoscope. In Experiment 1, all items were shifted in depth by the same amount while the adjustable probe stayed at the fixed middle position. We found that presenting ensembles in an apparently remote plane made observers overestimate the mean size, which is consistent with angular sizes being rescaled to distance. In Experiment 2, we presented individual sizes in different planes. While angular sizes and apparent distances were kept controlled across conditions, we only manipulated correlations between them. These manipulations affected the precision of size averaging in line with changes in the range of apparent rather than angular sizes. This pattern is possible only if the visual system rescales each individual size to its distance prior to averaging. Our finding demonstrates that ensemble summaries of basic features, such as size, can be based on quite elaborated representations of multiple objects. We also discuss important implications for size constancy. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Making sense of the world requires perceptual constancy—the stable perception of an object across changes in one’s sensation of it. To investigate whether constancy is intrinsic to perception, we tested whether humans can learn a form of constancy that is unique to a novel sensory skill (here, the perception of objects through click-based echolocation). Participants judged whether two echoes were different either because: (a) the clicks were different, or (b) the objects were different. For differences carried through spectral changes (but not level changes), blind expert echolocators spontaneously showed a high constancy ability (mean d′ = 1.91) compared to sighted and blind people new to echolocation (mean d′ = 0.69). Crucially, sighted controls improved rapidly in this ability through training, suggesting that constancy emerges in a domain with which the perceiver has no prior experience. This provides strong evidence that constancy is intrinsic to human perception., Public Significance Statement This study shows that people who learn a new skill to sense their environment - here: listening to sound echoes - can correctly represent the physical properties of objects. This result has implications for effectively rehabilitating people with sensory loss.

To achieve perceptual constancy, listeners utilize contextual cues to normalize speech variabilities in speakers. The present study tested the time course of this cognitive process with an event-related potential (ERP) experiment. The first neurophysiological evidence of speech normalization is observed in P2 (130–250 ms), which is functionally related to phonetic and phonological processes. Furthermore, the normalization process was found to ease lexical retrieval, as indexed by smaller N400 (350–470 ms) after larger P2. A cross-language vowel perception task was carried out to further specify whether normalization was processed in the phonetic and/or phonological stage(s). It was found that both phonetic and phonological cues in the speech context contributed to vowel normalization. The results suggest that vowel normalization in the speech context can be observed in the P2 time window and largely overlaps with phonetic and phonological processes.

Perceptual constancy requires the brain to maintain a stable representation of sensory input. In the olfactory system, activity in primary olfactory cortex (piriform cortex) is thought to determine odour identity1–5. Here we present the results of electrophysiological recordings of single units maintained over weeks to examine the stability of odour-evoked responses in mouse piriform cortex. Although activity in piriform cortex could be used to discriminate between odorants at any moment in time, odour-evoked responses drifted over periods of days to weeks. The performance of a linear classifier trained on the first recording day approached chance levels after 32 days. Fear conditioning did not stabilize odour-evoked responses. Daily exposure to the same odorant slowed the rate of drift, but when exposure was halted the rate increased again. This demonstration of continuous drift poses the question of the role of piriform cortex in odour perception. This instability might reflect the unstructured connectivity of piriform cortex6–12, and may be a property of other unstructured cortices. All odours elicit a unique pattern of neuronal activity in primary olfactory cortex but these patterns drift over time, posing a problem for the perceptual constancy of odours.

Although it has been proposed that birds acquire visual depth cues through dynamic head movements, behavioral evidence on how birds use motion parallax depth cues caused by self-motion is lacking. This study investigated whether self-generated motion parallax modulates pecking motor control and visual size perception in pigeons (Columba livia). We trained pigeons to peck a target on a touch monitor and to classify it as small or large. To manipulate motion parallax of the target, we changed the target position on the monitor according to the bird's head position in real time using a custom-built head tracker with two cameras. Pecking motor control was affected by the manipulation of motion parallax: when the motion parallax signified the target position farther than the monitor surface, the head position just before pecking to target was near the monitor surface, and vice versa. By contrast, motion parallax did not affect how the pigeons classified target sizes, implying that motion parallax might not contribute to size constancy in pigeons. These results indicate that motion parallax via head movements modulates pecking motor control in pigeons, suggesting that head movements of pigeons have the visual function of accessing motion parallax depth cues.

With the increase in popularity of consumer virtual reality headsets, for research and other applications, it is important to understand the accuracy of 3D perception in VR. We investigated the perceptual accuracy of near-field virtual distances using a size and shape constancy task, in two commercially available devices. Participants wore either the HTC Vive or the Oculus Rift and adjusted the size of a virtual stimulus to match the geometric qualities (size and depth) of a physical stimulus they were able to refer to haptically. The judgments participants made allowed for an indirect measure of their perception of the egocentric, virtual distance to the stimuli. The data show under-constancy and are consistent with research from carefully calibrated psychophysical techniques. There was no difference in the degree of constancy found in the two headsets. We conclude that consumer virtual reality headsets provide a sufficiently high degree of accuracy in distance perception, to allow them to be used confidently in future experimental vision science, and other research applications in psychology.

The closer an object is, the more the eyes have to rotate to fixate on it. This degree of eye rotation (or vergence) is thought to play an essential role in size constancy, the process of perceiving an object as having a constant physical size despite changes in distance. But vergence size constancy has never been tested divorced from confounding cues such as changes in the retinal image. We control for these confounding cues and find no evidence of vergence size constancy. This has three important implications. First, we need a new explanation for binocular vision's contribution to visual scale. Second, the vergence modulation of neurons in V1 can no longer be responsible for size constancy. Third, given the role attributed to vergence in multisensory integration, multisensory integration appears to be more reliant on cognitive factors than previous thought.

In three experiments, a bias to inflate in drawing the proportion of an image on a mirror over the mirror itself is demonstrated in a sample ( N = 146) of undergraduate students taking introductory psychology classes. The inflation is not confined to the image of one’s own head but is likely to occur in depictions of any object from a mirror with the mirror frame included. Having to include in the drawing background objects visible in the mirror is found to reduce the inflation. The inflation also diminishes with a smaller mirror and at a longer viewing distance. An account for the inflation in terms of a mechanism of size constancy contingent on selective attention is offered. The size of the inflation suggests a conflation of the perceived mirror image size with the size of the distal object it signals rather than a complete take-over by the latter. The reduction of the size inflation when participants are asked draw both a target and background objects is more likely a result of the selective attention to proportional relationships in the mirror scene, rather than a manifestation of an evenly scaled visual space under distributed visual spatial attention. The implications of the findings to improving proportional accuracy in observational drawing are discussed.

Do the physical facts of the viewed environment account for the ordinary experiences we have of that environment? According to standard philosophical views, distal facts do account for our experiences, a phenomenon explained by appeal to perceptual constancy, the phenomenal stability of objects and environmental properties notwithstanding physical changes in proximal stimulation. This essay reviews a significant but neglected research tradition in experimental psychology according to which percepts systematically do not correspond to mind-independent distal facts. Instead, stability of percept values comes in degrees, and physical facts about the viewed environment alone do not account for our ordinary experiences of the world. I conclude that more attention to descriptive research in psychophysics is warranted if what is sought is a philosophical theory of the nature of our perceptual relation with the world.

We are generally able to identify sounds and understand speech with ease, despite the large variations in the acoustics of each sound, which occur due to factors such as different talkers, background noise, and room acoustics. This form of perceptual constancy is likely to be mediated in part by the auditory system's ability to adapt to the ongoing environment or context in which sounds are presented. Auditory context effects have been studied under different names, such as spectral contrast effects in speech and auditory enhancement effects in psychoacoustics, but they share some important properties and may be mediated by similar underlying neural mechanisms. This review provides a survey of recent studies from our laboratory that investigate the mechanisms of speech spectral contrast effects and auditory enhancement in people with normal hearing, hearing loss, and cochlear implants. We argue that a better understanding of such context effects in people with normal hearing may allow us to restore some of these important effects for people with hearing loss via signal processing in hearing aids and cochlear implants, thereby potentially improving auditory and speech perception in the complex and variable everyday acoustic backgrounds that surround us.

The ability to keep perception constant despite environmental changes of illumination, viewing angle, or distance is a key feature of perception. Here, we investigated how "perceptual constancy" relates to language learning by investigating the relationship between color constancy and color term knowledge in 3- and 4-year-old children. We used a novel method to test color constancy where children are required to match colored stimuli under different illuminations. We found a positive relationship between color constancy and color term knowledge; children who knew more color words also had better color constancy. The relationship remained even when accounting for the effect of age and ability to discriminate colors. The findings have implications for understanding the development of perceptual constancy, language learning, and the link between perceptual processing and cognitive development.

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Depth information is necessary for perceiving the real size of objects at varying visual distances. To investigate to what extent this size constancy present in another vertebrate class, we addressed the two questions using pigeons: (a) whether pigeons see a corridor illusion based on size constancy and (b) whether pigeons prioritize pictorial cues over motion parallax cues for size constancy, like humans. We trained pigeons to classify target sizes on a corridor. In addition, we presented a dynamic version of corridor illusion in which the target and corridor moved side by side. Target speed was changed to manipulate motion parallax. With the static corridor, pigeons overestimated the target size when it was located higher, indicating that pigeons see a corridor illusion like humans. With the dynamic corridor, the pigeons overestimated the target size depending on target position, as in the static condition, but target speed did not affect their responses, indicating that the pictorial precedence also applies to pigeons. In a follow-up experiment using the same stimulus, we confirmed that humans perceive object size based on pictorial cues. These results suggest that size constancy characteristics are highly similar between pigeons and humans, despite the differences in their phylogeny and neural systems.

Human perception requires the many-to-one mapping between continuous sensory elements and discrete categorical representations. This grouping operation underlies the phenomenon of categorical perception (CP)—the experience of perceiving discrete categories rather than gradual variations in signal input. Speech perception requires CP because acoustic cues do not share constant relations with perceptual-phonetic representations. Beyond facilitating perception of unmasked speech, we reasoned CP might also aid the extraction of target speech percepts from interfering sound sources (i.e., noise) by generating additional perceptual constancy and reducing listening effort. Specifically, we investigated how noise interference impacts cognitive load and perceptual identification of unambiguous (i.e., categorical) vs. ambiguous stimuli. Listeners classified a speech vowel continuum (/u/-/a/) at various signal-to-noise ratios (SNRs [unmasked, 0 and −5 dB]). Continuous recordings of pupil dilation measured processing effort, with larger, later dilations reflecting increased listening demand. Critical comparisons were between time-locked changes in eye data in response to unambiguous (i.e., continuum endpoints) tokens vs. ambiguous tokens (i.e., continuum midpoint). Unmasked speech elicited faster responses and sharper psychometric functions, which steadily declined in noise. Noise increased pupil dilation across stimulus conditions, but not straightforwardly. Noise-masked speech modulated peak pupil size (i.e., [0 and −5 dB] > unmasked). In contrast, peak dilation latency varied with both token and SNR. Interestingly, categorical tokens elicited earlier pupil dilation relative to ambiguous tokens. Our pupillary data suggest CP reconstructs auditory percepts under challenging listening conditions through interactions between stimulus salience and listeners’ internalized effort and/or arousal.

Explanations of the Ponzo size illusion, the simultaneous contrast illusion, and the Craik-O’Brien-Cornsweet brightness illusions involve either stimulus-driven processes (assimilation, enhanced contrast, and anchoring) or prior experiences. Real-world up-down asymmetries for typical direction of illumination and ground planes in our physical environment should influence these illusions if they are experience based, but not if they are stimulus driven. Results presented here demonstrate differences in illusion strengths between upright and inverted versions of all three illusions. A left-right asymmetry of the Cornsweet illusion was produced by manipulating the direction of illumination, providing further support for the involvement of an experience-based explanation. When the inducers were incompatible with the targets being located at the different distances, the Ponzo illusion persisted and so did the influence from orientation, providing evidence for involvement of processes other than size constancy. As defined here, upright for the brightness illusions is consistent with an interpretation of a shaded bulging surface and a 3D object resulting from a light-from-above assumption triggering compensation for varying illumination. Upright for the Ponzo illusion is consistent with the inducers in the form of converging lines being interpreted as railway tracks receding on the ground triggering size constancy effects. The implications of these results, and other results providing evidence against experience-based accounts of the illusions, are discussed.

Naive realism is often characterized, by its proponents and detractors alike, as the view that for a subject to undergo a perceptual experience is for her to stand in a simple two-place acquaintance relation toward an object. However, two of the leading defenders of naive realism, John Campbell and Bill Brewer, have thought it necessary to complicate this picture, claiming that a third relatum is needed to account for various possible differences between distinct visual experiences of the same object (for example, differences that result from changes in the object’s spatial orientation relative to the subject, or from changes in the intensity with which the subject focuses her attention on the object). This, I argue, is a mistake. Once it is acknowledged that a subject’s visual experience acquaints her with more than just a single object, all of the relevant facts can be explained from within the simpler naive realist framework.

For very rough surfaces, friction-induced vibrations contain frequencies that change in proportion to sliding speed. Given the poor capacity of the somatosensory system to discriminate frequencies, this fact raises the question of how accurately finger sliding speed must be known during the reproduction of virtual textures with a surface tactile display. During active touch, ten observers were asked to discriminate texture recordings corresponding to different speeds. The samples were constructed from a common texture, which was resampled at various frequencies to give a set of stimuli of different swiping speeds. In trials, they swiped their finger in rapid succession over a glass plate, which vibrated to accurately reproduce three texture recordings. Two of these recordings were identical and a third differed in that the sample represented a texture swiped at a speed different from the other two. Observers identified which of the three samples felt different. For a metal mesh texture recording, seven observers reported differences when the speed varied by 60, 80, and 100mm/s while the other three did not reach a discrimination threshold. For a finer leather chamois texture recording, thresholds were never reached in the 100mm/s range. These results show that the need for high-accuracy measurement of swiping speed during texture reproduction may actually be quite limited compared to what is commonly found in the literature.

The nondeterministic relationship between speech acoustics and abstract phonemic representations imposes a challenge for listeners to maintain perceptual constancy despite the highly variable acoustic realization of speech. Talker normalization facilitates speech processing by reducing the degrees of freedom for mapping between encountered speech and phonemic representations. While this process has been proposed to facilitate the perception of ambiguous speech sounds, it is currently unknown whether talker normalization is affected by the degree of potential ambiguity in acoustic-phonemic mapping. We explored the effects of talker normalization on speech processing in a series of speeded classification paradigms, parametrically manipulating the potential for inconsistent acoustic-phonemic relationships across talkers for both consonants and vowels. Listeners identified words with varying potential acoustic-phonemic ambiguity across talkers (e.g., beet/boat vs. boot/boat) spoken by single or mixed talkers. Auditory categorization of words was always slower when listening to mixed talkers compared to a single talker, even when there was no potential acoustic ambiguity between target sounds. Moreover, the processing cost imposed by mixed talkers was greatest when words had the most potential acoustic-phonemic overlap across talkers. Models of acoustic dissimilarity between target speech sounds did not account for the pattern of results. These results suggest (i) that talker normalization incurs the greatest processing cost when disambiguating highly-confusable sounds and (ii) that talker normalization appears to be an obligatory component of speech perception, taking place even when the acoustic-phonemic relationships across sounds are unambiguous.

The primate visual system contains specialised neural mechanisms for encoding the direction of others’ gaze. A foundational question that we can ask in this domain concerns the frame of reference in which another person’s gaze is represented. Electrophysiological recordings in macaque monkeys suggest that direction of gaze might be encoded relative to the observer (i.e., in a first person reference frame) or relative to the head or body of the stimulus (i.e., in a second person reference frame). Here we use sensory adaptation to gaze direction as a psychophysical tool to probe how this property of the environment is represented in the human visual system. We find that strong perceptual aftereffects occur following adaptation to images that share a common direction of gaze in the first person reference frame, but vary in their direction of gaze in the second person reference frame. In contrast, sensory aftereffects do not occur following adaptation to images that share a common direction of gaze in the second person reference frame. These findings suggest that the adaptive coding of gaze direction in the human visual system occurs primarily in a first-person coordinate system. These data also provide strong support for perceptual constancy in the context of perceived gaze direction, implying that the direction of others’ attention is represented in the brain as a higher-level perceptual property abstracted from lower-level cues (e.g., iris position and head rotation).

The “Innsbruck Goggle Experiments” on long-term wearing of reversing mirrors, prismatic and half prismatic goggles, and colored half goggles represent a milestone in research on adaptation (adapting to the introduced “disturbance”) and after-effects (after removal of the “disturbance”). By means of these goggles it is, for example, possible to invert or distort the visual field (such as flipping top and bottom or left and right), as well as to observe how individuals learn to change the image back to vertical or recognize left and right. The Innsbruck Experiments gave decisive momentum to further international research on the ontogenetic development of perception, special perception, color perception, perceptual constancy, sensorimotor coordination, as well as to the development of theories. In the current paper, aside from presenting the history and results of selected studies, we will give an introduction to the life and work of the protagonists of these studies in Innsbruck, namely Theodor Erismann (1883–1961) and Ivo Kohler (1915–1985). Furthermore, we will propose ideas for future research on cognition and neuroscience.

A new illusion is described. Randomly positioned dots moved radially within an imaginary annular window. The dots' motion periodically changed the direction, leading to an alternating percept of expanding and contracting motion. Strikingly, the apparent size of the enclosed circular region shrank during the dots' expanding phases and dilated during the contracting phases. We quantitatively measured the illusion, and found that the presence of energy at the local kinetic edge could not account for the illusion. Besides, we reproduced the illusion on a natural scene background seen from a first-person point of view that moved forward and backward periodically. Blurring the boundaries of motion areas could not reverse the illusion in all subjects. Taken together, our observed illusion is likely induced by optic flow processing with some components of motion contrast. Expanding or contracting dots may induce the self-motion perception of either approaching or leaving way from the circle. These will make the circle appear smaller or larger since its retinal size remains constant.

In recent discussions of two important issues in the philosophy of perception, viz. the problems of perceptual presence and perceptual constancy, Merleau-Ponty's ideas have been garnering attention thanks to the work of Sean Kelly and Alva Noe. Although both Kelly's normative approach and Noe's enactive approach highlight important aspects of Merleau-Ponty's view, I argue that neither does full justice to it because they overlook the central role that style plays in his solution to these problems. I show that a closer look at the Phenomenology and several other texts from this period reveals that, on Merleau-Ponty's account, we are able to perceive the absent features of objects as present, constant properties, and constant objects because we recognize that the objects we perceive have a unique style that persists through and unifies all their appearances.

Summary Object constancies are central constructs in theories of visual phenomenology. A powerful example is "size constancy," in which the perceived size of an object remains stable despite changes in viewing distance [1–4]. Evidence from neuropsychology [5], neuroimaging [6–11], transcranial magnetic stimulation [12, 13], single-unit and lesion studies in monkey [14–20], and computational modeling [21] suggests that re-entrant processes involving reciprocal interactions between primary visual cortex (V1) and extrastriate visual areas [22–26] play an essential role in mediating size constancy. It is seldom appreciated, however, that object constancies must also operate for the visual guidance of goal-directed action. For example, when reaching out to pick up an object, the hand's in-flight aperture scales with size of the goal object [27–30] and is refractory to the decrease in retinal-image size with increased viewing distance [31–41] (Figure 1), a phenomenon we call "grip constancy." Does grip constancy, like perceptual constancy, depend on V1 or can it be mediated by pathways that bypass it altogether? We tested these possibilities in an individual, M.C., who has bilateral lesions encompassing V1 and much of the ventral visual stream. We show that her perceptual estimates of object size co-vary with retinal-image size rather than real-world size as viewing distance varies. In contrast, M.C. shows near-normal scaling of in-flight grasp aperture to object size despite changes in viewing distance. Thus, although early visual cortex is necessary for perceptual object constancy, it is unnecessary for grip constancy, which is mediated instead by separate visual inputs to dorsal-stream visuomotor areas [42–48].

Size constancy is the ability to perceive objects as remaining constant in size regardless of their distance from the observer. Emmert's law demonstrates that viewing distance determines the perceived size of afterimages according to the amount of depth cues that are available. Using an afterimage paradigm, we examined to what extent removing stereopsis and other depth cues affects size-distance scaling. Thirty participants 'projected' afterimages onto a surface presented at different distances under binocular, monocular, and eyes-closed conditions. The perceived size of the afterimages closely followed the size-distance scaling predictions made by Emmert's law under binocular testing conditions, when all depth cues were available. In contrast, monocular testing decreased adherence to Emmert's law, while the eyes-closed condition resulted in a greater breakdown of size-distance scaling. Because we used an afterimage paradigm, this study provides the first demonstration of how perceived size is modulated by the availability of depth cues under conditions with a constant retinal image stimulus.

© 2019 Elsevier Ltd Our visual system provides a distance-invariant percept of object size by integrating retinal image size with viewing distance (size constancy). Single-unit studies with animals have shown that some distance cues, especially oculomotor cues such as vergence and accommodation, can modulate the signals in the thalamus or V1 at the initial processing stage [1–7]. Accordingly, one might predict that size constancy emerges much earlier in time [8–10], even as visual signals are being processed in the thalamus. So far, the studies that have looked directly at size coding have either used fMRI (poor temporal resolution [11–13]) or relied on inadequate stimuli (pictorial illusions presented on a monitor at a fixed distance [11, 12, 14, 15]). Here, we physically moved the monitor to different distances, a more ecologically valid paradigm that emulates what happens in everyday life and is an example of the increasing trend of “bringing the real world into the lab.” Using this paradigm in combination with electroencephalography (EEG), we examined the computation of size constancy in real time with real-world viewing conditions. Our study provides strong evidence that, even though oculomotor distance cues have been shown to modulate the spiking rate of neurons in the thalamus and in V1, the integration of viewing distance cues and retinal image size takes at least 150 ms to unfold, which suggests that the size-constancy-related activation patterns in V1 reported in previous fMRI studies (e.g., [12, 13]) reflect the later processing within V1 and/or top-down input from other high-level visual areas. Chen et al. examine the computation of size constancy using EEG in a real-world setting in which the stimuli are viewed from different distances. They show that even when the distance cues are strong and congruent, none of them has any effect on the early event-related potential (ERP) components. Size constancy takes time to evolve even though that time is short (∼150 ms).

Does the sense of smell involve the perception of odor objects? General discussion of perceptual objecthood centers on three criteria: stimulus representation, perceptual constancy, and figure-ground segregation. These criteria, derived from theories of vision, have been applied to olfaction in recent philosophical debates about psychology. An inherent problem with such framing of olfactory objecthood is that philosophers explicitly ignore the constitutive factors of the sensory systems that underpin the implementation of these criteria. The biological basis of odor coding is fundamentally different from the coding principles of the visual system. This article analyzes the three measures of perceptual objecthood against the biological background of the olfactory system. It contrasts the coding principles in olfaction with the visual system to show why these criteria of objecthood fail to be instantiated in odor perception. The argument demonstrates that olfaction affords perceptual categorization without the need to form odor objects.

Although social contingency, namely contingent reactions of other to one's own actions, critically affects attachment formation, can it also modulate the perceived distance between self and other? Previous studies have suggested a positive answer. However, these studies are criticized for not showing true top-down effects on perception because of pitfalls such as task demands. We show that social contingency reduced the perceived distance between self and other while avoiding pitfalls. According to Emmert’s law, the perceived size of an afterimage increases with perceived distance. Thus, if social contingency modulates the perceived distance, the perceived size of afterimage should inevitably reflect it. The results showed that the size of the afterimages of a face that contingently responded to participants’ actions was perceived as smaller than those of non-contingent and unresponsive faces. This effect was more salient with increasing viewing distances. Thus, prior knowledge of interaction with environment modulates online perceptual processing in size constancy, probably through its influence on perceived distance.

In this chapter, I discuss Tyler Burge’s account of the origins of objectivity. According to him, perceptual representation has a proto-predicational structure, represents the distal (as opposed to the proximal) stimulus and is necessarily governed by non-biological teleology. Furthermore, Burge argues that there is detailed empirical evidence for this conception of perceptual representation, as a mature scientific discipline, perceptual psychology, uses this conception in mathematically rigorous, predictively successful descriptions of the visual system of animal species. I discuss Burge’s proposal with an eye looking backward and an eye looking forward, as it were. First, the account adds to the critique of Quine’s own mature proposal by suggesting that Quine has been superseded by the progress of science. Second, I consider the merits of Burge’s account as an attempt at naturalized epistemology in its own rights.

Contains fulltext : 208867.pdf (Publisher’s version ) (Open Access) When searching for relevant objects in our environment (say, an apple), we create a memory template (a red sphere), which causes our visual system to favor template-matching visual input (applelike objects) at the expense of template-mismatching visual input (e.g., leaves). Although this principle seems straightforward in a lab setting, it poses a problem in naturalistic viewing: Two objects that have the same size on the retina will differ in real-world size if one is nearby and the other is far away. Using the Ponzo illusion to manipulate perceived size while keeping retinal size constant, we demonstrated across 71 participants that visual objects attract attention when their perceived size matches a memory template, compared with mismatching objects that have the same size on the retina. This shows that memory templates affect visual selection after object representations are modulated by scene context, thus providing a working mechanism for template-based search in naturalistic vision. 13 p.

According to numerous studies observers can rapidly and precisely evaluate mean or range of the set. Recent studies have shown that the mean size estimated based on sizes of objects rescaled to their distances (Tiurina & Utochkin, 2019). In the current study, we directly tested this rescaling mechanism on the perception of range using binocular and monocular cues.In Experiment 1, a sample set of circles with different angular sizes and in different apparent distances were stereoscopically presented. Participants had to adjust the range of the test set to match the range of the sample set. The main manipulation was the size-distance correlation for sample and test sets: in negative size-distance correlation, the apparent range had to decrease, while in positive correlation - increase. We found the highest underestimation in the condition with the negative sample correlation and positive test correlation, which could be explained only if ensemble summary statistics were estimated after the item's rescaling.In Experiment 2, we used Ponzo-like illusion and spatial positions as a depth cue. Sets were presented with positive, negative or without size-distance correlation on a grey background or the background with Ponzo-like illusion. We found that the range was underestimated in negative correlation and overestimated in positive correlation.Thus, items of ensemble could be automatically rescaled according to their distance, based on both binocular and monocular cues, and ensemble summary statistics estimation is based on perceived sizes.

Deficits in perceptual constancies from early infancy have been proposed to contribute to autism and exacerbate its symptoms (Hellendoorn et al., Frontiers in Psychology 6:1–16, 2015). Here, we examined size constancy in adults from the general population (N = 106) with different levels of self-reported autistic traits using an approach based on negative afterimages. The afterimage strength, as indexed by duration and vividness, was also quantified. In opposition to the Hellendoorn and colleagues’ model, we were unable to demonstrate any kind of relationship between abilities in size constancy and autistic traits. However, our results demonstrated that individuals with higher degrees of autistic traits experienced more persistent afterimages. We discuss possible retinal and post-retinal explanations for prolonged afterimages in people with higher levels of autistic traits. Electronic supplementary material The online version of this article (doi:10.1007/s10803-016-2971-6) contains supplementary material, which is available to authorized users.

When perceiving speech, listeners compensate for reverberation and stable spectral peaks in the speech signal. Despite natural listening conditions usually adding both reverberation and spectral coloration, these processes have only been studied separately. Reverberation smears spectral peaks across time, which is predicted to increase listeners’ compensation for these peaks. This prediction was tested using sentences presented with or without a simulated reverberant sound field. All sentences had a stable spectral peak (added by amplifying frequencies matching the second formant frequency [F2] in the target vowel) before a test vowel varying from /i/ to /u/ in F2 and spectral envelope (tilt). In Experiment 1, listeners demonstrated increased compensation (larger decrease in F2 weights and larger increase in spectral tilt weights for identifying the target vowel) in reverberant speech than in nonreverberant speech. In Experiment 2, increased compensation was shown not to be due to reverberation tails. In Experiment 3, adding a pure tone to nonreverberant speech at the target vowel’s F2 frequency increased compensation, revealing that these effects are not specific to reverberation. Results suggest that perceptual adjustment to stable spectral peaks in the listening environment is not affected by their source or cause.