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1.
Perception ; 50(3): 195-215, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33583254

RESUMO

The descriptions of surfaces, objects, and events computed by visual processes are not solely for consumption in the visual system but are meant to be passed on to other brain centers. Clearly, the description of the visual scene cannot be sent in its entirety, like a picture or movie, to other centers, as that would require that each of them have their own visual system to decode the description. Some very compressed, annotated, or labeled version must be constructed that can be passed on in a format that other centers-memory, language, planning-can understand. If this is a "visual language," what is its grammar? In a first pass, we see, among other things, differences in processing of visual "nouns," visual "verbs," and visual "prepositions." Then we look at recursion and errors of visual grammar. Finally, the possibility of a visual language also raises the question of the acquisition of its grammar from the visual environment and the chance that this acquisition process was borrowed and adapted for spoken language.

2.
Atten Percept Psychophys ; 83(4): 1455-1462, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33400220

RESUMO

Illusions can induce striking differences between perception and retinal input. For instance, a static Gabor with a moving internal texture appears to be shifted in the direction of its internal motion, a shift that increases dramatically when the Gabor itself is also in motion. Here, we ask whether attention operates on the perceptual or physical location of this stimulus. To do so, we generated an attentional tracking task where participants (N = 15) had to keep track of a single target among three Gabors that rotated around a common center in the periphery. During tracking, the illusion was used to make three Gabors appear either shifted away from or toward one another while maintaining the same physical separation. Because tracking performance depends in part on target to distractor spacing, if attention selects targets from perceived positions, performance should be better when the Gabors appear further apart and worse when they appear closer together. We find that tracking performance is superior with greater perceived separation, implying that attentional tracking operates over perceived rather than physical positions.


Assuntos
Ilusões , Percepção de Movimento , Atenção , Humanos , Estimulação Luminosa
3.
Front Hum Neurosci ; 14: 570419, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33192401

RESUMO

Attention can be oriented in space covertly without the need of eye movements. We used multivariate pattern classification analyses (MVPA) to investigate whether the time course of the deployment of covert spatial attention leading up to the observer's perceptual decision can be decoded from both EEG alpha power and raw activity traces. Decoding attention from these signals can help determine whether raw EEG signals and alpha power reflect the same or distinct features of attentional selection. Using a classical cueing task, we showed that the orientation of covert spatial attention can be decoded by both signals. However, raw activity and alpha power may reflect different features of spatial attention, with alpha power more associated with the orientation of covert attention in space and raw activity with the influence of attention on perceptual processes.

4.
Iperception ; 11(5): 2041669520939107, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33014325

RESUMO

When an annulus in fast apparent motion reverses its contrast over time, the foveal and peripheral percepts are strikingly different. In central vision, the annulus appears to follow the same path as an annulus without flicker, whereas in the periphery, the stimulus seems to randomly jump across the screen. The illusion strength depends on motion speed and reversal rate. Our observations suggest that it results from a balance between conflicting phi and reverse-phi motion, positional uncertainty, and attention. In addition to illustrating the differences between central and peripheral motion processing, this illusion shows that both discrete positional sampling and motion energy combine to generate motion percepts, although with eccentricity dependent weights that are themselves affected by attention.

5.
Sci Rep ; 10(1): 14263, 2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32868794

RESUMO

Speaking more than one language has been associated with enhanced cognitive capacities. Here we evaluated whether bilingual individuals have advantages in visual tracking attention. Adult bilingual (n = 35) and monolingual (n = 35) participants were tested in the Multiple Object Tracking task (MOT). In one condition, the MOT was performed by itself establishing the baseline performance of each group, and in the other condition, it was performed while participants counted backward out loud in their mother tongue. At baseline, the average speed tracking threshold of bilinguals was not better than that of the monolinguals. Importantly, for bilinguals, counting backward decreased their threshold by only 15%, but, for monolinguals, it decreased it three times as much. This result suggests that bilingualism confers advantages to visual tracking attention when dual tasking is required, extending the evidence that bilingualism affords cognitive benefits beyond verbal communication.

6.
Atten Percept Psychophys ; 82(6): 3065-3071, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32378147

RESUMO

If a patch of texture drifts in one direction while its internal texture drifts in the orthogonal direction, the perceived direction of this double-drift stimulus (also known as the infinite regress and curveball illusions) deviates strongly from its physical direction. Here, we use double-drift stimuli to construct two types of search arrays: The first had an oddball target in terms of the physical trajectories, but no oddball for the perceived trajectory, whereas the second had a perceptual oddball, but no physical oddball. We used these two arrays to determine whether pop-out operates over physical or perceived trajectories. Participants reported the location of the odd double-drift stimulus that had either a unique physical or perceived trajectory in a set of four or eight items. When the distractors all shared one perceived trajectory, but the target had an odd perceived trajectory, it popped out even though the physical trajectories of the stimuli were mixed: Accuracy rates were at ceiling, and response times decreased with increasing set size. In contrast, participants were significantly less accurate and slower at finding the physical oddball when all the paths had a common perceived trajectory. Moreover, responses became less accurate and slower with increasing set size. Our findings suggest that, at least for this type of stimulus, perceptual features can be processed rapidly, whereas the search for physical features is very inefficient.

7.
Front Neurosci ; 14: 217, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32256310

RESUMO

We generally experience a stable visual world in spite of regular disruptions caused by our own movements (saccades, blinks) or by the visual input itself (flashes, occlusions). In trying to understand the mechanisms responsible for this stability, saccades have been particularly well-studied, and a number of peri-saccadic perceptual distortions (spatial and temporal compression, failure to detect target displacement) have been explored. It has been shown that some of these distortions are not saccade specific, but also arise when the visual input is instead abruptly and briefly masked. Here, we demonstrate that another peri-saccadic distortion, the reversal of the temporal order of a pair of brief events, may also be found with masking. Human participants performed a temporal order judgment task, and the timing of stimuli and mask was varied over trials. Perceptual order was reversed on ~25% of the trials at the shortest stimulus to mask intervals. This was not merely a failure of target detection, since participants often reported these reversals with high subjective confidence. These findings update the constraints on models of stability around disruptions.

9.
J Vis ; 19(14): 2, 2019 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-31826247

RESUMO

If a Gabor pattern drifts in one direction while its internal texture drifts in the orthogonal direction, its perceived direction deviates strongly from its true direction and is instead some combination of its real external motion and its internal motion (Tse & Hsieh, 2006). In the first experiment, we confirm that, for the stimuli used in our experiment, the direction shifts on a gray background were explained by a vector combination of the internal and external motions whereas for the Gabor on a black background, we find no illusory shifts. These results suggest that the internal motion contributes to the perceived direction but only when the Gabor's positional uncertainty is high. Next, we test whether the vector combination is based on motions on the retina or motions in the world. When participants track a fixation point that moves in tandem with the Gabor, keeping it roughly stable on the retina, the illusion is undiminished. This finding indicates that the vector combination of internal and external motion that produces the double-drift illusion must happen after the eye movement signals have been factored into the stimulus motions to recover motions in the world, in particular, in areas V3A, V6, MSTd, and VIP.


Assuntos
Ilusões/fisiologia , Percepção de Movimento/fisiologia , Acompanhamento Ocular Uniforme/fisiologia , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodos , Adulto Jovem
10.
Curr Biol ; 29(23): 4036-4044.e4, 2019 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-31761706

RESUMO

When perception differs from the physical stimulus, as it does for visual illusions and binocular rivalry, the opportunity arises to localize where perception emerges in the visual processing hierarchy. Representations prior to that stage differ from the eventual conscious percept even though they provide input to it. Here, we investigate where and how a remarkable misperception of position emerges in the brain. This "double-drift" illusion causes a dramatic mismatch between retinal and perceived location, producing a perceived motion path that can differ from its physical path by 45° or more. The deviations in the perceived trajectory can accumulate over at least a second, whereas other motion-induced position shifts accumulate over 80-100 ms before saturating. Using fMRI and multivariate pattern analysis, we find that the illusory path does not share activity patterns with a matched physical path in any early visual areas. In contrast, a whole-brain searchlight analysis reveals a shared representation in anterior regions of the brain. These higher-order areas would have the longer time constants required to accumulate the small moment-to-moment position offsets that presumably originate in early visual cortical areas and then transform these sensory inputs into a final conscious percept. The dissociation between perception and the activity in early sensory cortex suggests that consciously perceived position does not emerge in what is traditionally regarded as the visual system but instead emerges at a higher level.


Assuntos
Encéfalo/fisiologia , Estado de Consciência , Ilusões/fisiologia , Percepção de Movimento/fisiologia , Adulto , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Córtex Visual/fisiologia , Adulto Jovem
11.
J Vis ; 19(13): 9, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31715632

RESUMO

In the flash-grab effect, when a disk is flashed on a moving background at the moment it reverses direction, the perceived location of the disk is strongly displaced in the direction of the motion that follows the reversal. Here, we ask whether increased expectation of the reversal reduces its effect on the motion-induced shift, as suggested by predictive coding models with first order predictions. Across four experiments we find that when the reversal is expected, the illusion gets stronger, not weaker. We rule out accumulating motion adaptation as a contributing factor. The pattern of results cannot be accounted for by first-order predictions of location. Instead, it appears that second-order predictions of event timing play a role. Specifically, we conclude that temporal expectation causes a transient increase in temporal attention, boosting the strength of the motion signal and thereby increasing the strength of the illusion.


Assuntos
Percepção de Movimento/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa , Adulto , Feminino , Humanos , Ilusões/fisiologia , Masculino , Adulto Jovem
12.
Perception ; 48(2): 115-137, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30799731

RESUMO

We investigated artificial scotomas created when a moving object instantaneously crossed a gap, jumping ahead and continuing its otherwise smooth motion. Gaps of up to 5.1 degrees of visual angle, presented at 18° eccentricity, either closed completely or appeared much shorter than when the same gap was crossed by two-point apparent motion, or crossed more slowly, mimicking occlusion. Prolonged exposure to motion trajectories with a gap in most cases led to further shrinking of the gap. The same gap-shrinking effect has previously been observed in touch. In both sensory modalities, it implicates facilitation among codirectional local motion detectors and motion neurons with receptive fields larger than the gap. Unlike stimuli that simply deprive a receptor surface of input, suggesting it is insentient, our motion pattern skips a section in a manner that suggests a portion of the receptor surface has been excised, and the remaining portions stitched back together. This makes it a potentially useful tool in the experimental study of plasticity in sensory maps.


Assuntos
Percepção de Movimento/fisiologia , Escotoma/fisiopatologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa , Adulto Jovem
13.
Atten Percept Psychophys ; 81(1): 85-97, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30288690

RESUMO

Our perception of the world remains stable despite the retinal shifts that occur with each saccade. The role of spatial attention in matching pre- to postsaccadic visual information has been well established, but the role of feature-based attention remains unclear. In this study, we examined the transsaccadic processing of a color pop-out target. Participants made a saccade towards a neutral target and performed a search task on a peripheral array presented once the saccade landed. A similar array was presented just before the saccade and we analyzed what aspect of this preview benefitted the postsaccadic search task. We assessed the preview effect in the spatiotopic and retinotopic reference frames, and the potential transfer of feature selectivity across the saccade. In the first experiment, the target and distractor colors remained identical for the preview and the postsaccadic array and performance improved. The largest benefit was observed at the spatiotopic location. In the second experiment, the target and distractor colors were swapped across the saccade. All responses were slowed but the cost was least at the spatiotopic location. Our results show that the preview attracted spatial attention to the target location, which was then remapped, and suggest that previewed features, specifically colors, were transferred across the saccade. Furthermore, the preview induced a spatiotopic advantage regardless of whether the target switched color or not, suggesting that spatiotopy was established independently of feature processing. Our results support independent priming effects of features versus location and underline the role of feature-based selection in visual stability.


Assuntos
Atenção/fisiologia , Percepção de Cores/fisiologia , Estimulação Luminosa/métodos , Movimentos Sacádicos/fisiologia , Processamento Espacial/fisiologia , Adulto , Feminino , Humanos , Masculino , Retina/fisiologia , Adulto Jovem
14.
eNeuro ; 5(5)2018.
Artigo em Inglês | MEDLINE | ID: mdl-30294669

RESUMO

The perception of gender and age of unfamiliar faces is reported to vary idiosyncratically across retinal locations such that, for example, the same androgynous face may appear to be male at one location but female at another. Here, we test spatial heterogeneity for the recognition of the identity of personally familiar faces in human participants. We found idiosyncratic biases that were stable within participants and that varied more across locations for low as compared to high familiar faces. These data suggest that like face gender and age, face identity is processed, in part, by independent populations of neurons monitoring restricted spatial regions and that the recognition responses vary for the same face across these different locations. Moreover, repeated and varied social interactions appear to lead to adjustments of these independent face recognition neurons so that the same familiar face is eventually more likely to elicit the same recognition response across widely separated visual field locations. We provide a mechanistic account of this reduced retinotopic bias based on computational simulations.


Assuntos
Viés , Reconhecimento Facial/fisiologia , Relações Interpessoais , Reconhecimento Visual de Modelos/fisiologia , Reconhecimento Psicológico/fisiologia , Adulto , Face/fisiologia , Feminino , Humanos , Masculino , Adulto Jovem
15.
Iperception ; 9(5): 2041669518801029, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30302188

RESUMO

A spot moves vertically across a large grating of oblique parallel lines. When viewed peripherally, the motion path looks oblique, close to the orientation of the background grating. Even when the grating's orientation is concealed by crowding, it can still deflect the spot's perceived motion path.

16.
J Neurosci ; 38(38): 8243-8250, 2018 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-30104339

RESUMO

Transmission delays in the nervous system pose challenges for the accurate localization of moving objects as the brain must rely on outdated information to determine their position in space. Acting effectively in the present requires that the brain compensates not only for the time lost in the transmission and processing of sensory information, but also for the expected time that will be spent preparing and executing motor programs. Failure to account for these delays will result in the mislocalization and mistargeting of moving objects. In the visuomotor system, where sensory and motor processes are tightly coupled, this predicts that the perceived position of an object should be related to the latency of saccadic eye movements aimed at it. Here we use the flash-grab effect, a mislocalization of briefly flashed stimuli in the direction of a reversing moving background, to induce shifts of perceived visual position in human observers (male and female). We find a linear relationship between saccade latency and perceived position shift, challenging the classic dissociation between "vision for action" and "vision for perception" for tasks of this kind and showing that oculomotor position representations are either shared with or tightly coupled to perceptual position representations. Altogether, we show that the visual system uses both the spatial and temporal characteristics of an upcoming saccade to localize visual objects for both action and perception.SIGNIFICANCE STATEMENT Accurately localizing moving objects is a computational challenge for the brain due to the inevitable delays that result from neural transmission. To solve this, the brain might implement motion extrapolation, predicting where an object ought to be at the present moment. Here, we use the flash-grab effect to induce perceptual position shifts and show that the latency of imminent saccades predicts the perceived position of the objects they target. This counterintuitive finding is important because it not only shows that motion extrapolation mechanisms indeed work to reduce the behavioral impact of neural transmission delays in the human brain, but also that these mechanisms are closely matched in the perceptual and oculomotor systems.


Assuntos
Encéfalo/fisiologia , Movimentos Oculares/fisiologia , Percepção de Movimento/fisiologia , Percepção Visual/fisiologia , Feminino , Humanos , Masculino , Movimento (Física) , Estimulação Luminosa , Adulto Jovem
17.
Iperception ; 9(4): 2041669518770690, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30083307

RESUMO

A Cornsweet edge creates the perception of a step in surface lightness between two adjacent regions of identical mean luminance due to a gradient on both sides. We might imagine that in a concatenated set of these gradients, the lightness steps would accumulate, but they do not. However, a diamond pattern, with each diamond filled with an identical luminance gradient does give a cumulative Cornsweet effect. Here, we offer an illumination explanation for why the cumulative effect is visible in the diamonds but not in the basic ramp grating and we demonstrate that when the diamonds drift, they produce a strong brightening effect (depending on the direction of the motion) and a dimming aftereffect. These effects are consistent with the local luminance gradients and not with the global lightness shift of the cumulative Cornsweet effect.

18.
J Neurophysiol ; 119(6): 2091-2099, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29513148

RESUMO

When a Gabor patch moves along a path in one direction while its internal texture drifts orthogonally to this path, it can appear to deviate from its physical path by 45° or more. This double-drift illusion is different from other motion-induced position shift effects in several ways: it has an integration period of over a second; the illusory displacement that accumulates over a second or more is orthogonal to rather than along the motion path; the perceptual deviations are much larger; and they have little or no effect on eye movements to the target. In this study we investigated the underlying neural mechanisms of the motion integration and position processing for this double-drift stimulus by testing possible anatomical constraints on its magnitude. We found that the illusion was reduced at the vertical and horizontal meridians when the perceptual path would cross or be driven toward the meridian, but not at other locations or other motion directions. The disruption of the accumulation of the position error at both the horizontal and vertical meridians suggests a central role of quadrantic areas in the generation of this type of motion-induced position shift. NEW & NOTEWORTHY The remarkably strong double-drift illusion is disrupted at both the vertical and horizontal meridians. We propose that this finding is the behavioral consequence of the anatomical gaps at both meridians, suggesting that neural areas with quadrantic representations (e.g., V2, V3) are the initial locus of this motion-induced position shift. This result rules out V1 as the source of the illusion because it has an anatomical break only at the vertical meridian.


Assuntos
Percepção de Movimento , Ilusões Ópticas , Córtex Visual/fisiologia , Adulto , Movimentos Oculares , Feminino , Humanos , Masculino
19.
Atten Percept Psychophys ; 80(4): 884-893, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29476332

RESUMO

The double-drift stimulus produces a strong shift in apparent motion direction that generates large errors of perceived position. In this study, we tested the effect of attentional load on the perceptual estimates of motion direction and position for double-drift stimuli. In each trial, four objects appeared, one in each quadrant of a large screen, and they moved upward or downward on an angled trajectory. The target object whose direction or position was to be judged was either cued with a small arrow prior to object motion (low attentional load condition) or cued after the objects stopped moving and disappeared (high attentional load condition). In Experiment 1, these objects appeared 10° from the central fixation, and participants reported the perceived direction of the target's trajectory after the stimulus disappeared by adjusting the direction of an arrow at the center of the response screen. In Experiment 2, the four double-drift objects could appear between 6 ° and 14° from the central fixation, and participants reported the location of the target object after its disappearance by moving the position of a small circle on the response screen. The errors in direction and position judgments showed little effect of the attentional manipulation-similar errors were seen in both experiments whether or not the participant knew which double-drift object would be tested. This suggests that orienting endogenous attention (i.e., by only attending to one object in the precued trials) does not interact with the strength of the motion or position shifts for the double-drift stimulus.


Assuntos
Atenção/fisiologia , Percepção de Movimento/fisiologia , Orientação/fisiologia , Adulto , Sinais (Psicologia) , Feminino , Humanos , Masculino
20.
Atten Percept Psychophys ; 80(3): 723-737, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29327331

RESUMO

The cortical representations of a visual object differ radically across saccades. Several studies claim that the visual system adapts the peripheral percept to better match the subsequent foveal view. Recently, Herwig, Weiß, and Schneider (2015, Annals of the New York Academy of Sciences, 1339(1), 97-105) found that the perception of shape demonstrates a saccade-dependent learning effect. Here, we ask whether this learning actually requires saccades. We replicated Herwig et al.'s (2015) study and introduced a fixation condition. In a learning phase, participants were exposed to objects whose shape systematically changed during a saccade, or during a displacement from peripheral to foveal vision (without a saccade). In a subsequent test, objects were perceived as less (more) curved if they previously changed from more circular (triangular) in the periphery to more triangular (circular) in the fovea. Importantly, this pattern was seen both with and without saccades. We then tested whether a variable delay between the presentations of the peripheral and foveal objects would affect their association-hypothetically weakening it at longer delays. Again, we found that shape judgments depended on the changes experienced during the learning phase and that they were similar in both the saccade and fixation conditions. Surprisingly, they were not affected by the delay between the peripheral and foveal presentations over the range we tested. These results suggest that a general associative process, independent of saccade execution, contributes to the perception of shape across viewpoints.


Assuntos
Reconhecimento Visual de Modelos/fisiologia , Movimentos Sacádicos/fisiologia , Adulto , Calibragem , Feminino , Fóvea Central , Humanos , Julgamento , Aprendizagem , Masculino , Estimulação Luminosa/métodos , Adulto Jovem
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