Cortical dynamics of visual motion perception: Short-range and long-range apparent motion.

Describes further evidence for a new neural network theory of biological motion perception. The theory clarifies why parallel streams V1→V2, V1→MT, and V1→V2→MT exist for static form and motion form processing among the areas V1, V2, and MT of visual cortex. It also suggests that the static form system generates emergent boundary segmentations whose outputs are insensitive to direction-of-contrast and to direction-of-motion, whereas the motion form system generates emergent boundary segmentations whose outputs are insensitive to direction-of-contrast but sensitive to direction-of-motion. Data on short- and long-range apparent motion percepts are explained including beta, split, gamma and reverse-contrast gamma, and delta motions, as well as visual inertia. Also included are the transition from group motion to element motion in response to a Ternus display as the interstimulus interval (ISI) decreases; group motion in response to a reverse-contrast Ternus display even at short ISIs; speed-up of motion velocity as interflash distance increases or flash duration decreases dependence of the transition from element motion to group motion on stimulus duration and size, various classical dependencies between flash duration, spatial separation, ISI, and motion threshold known as Korte's laws; dependence of motion strength on stimulus orientation and spatial frequency; short-range and long-range form–color interactions; and binocular interactions of flashes to different eyes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional modulation of visual processes in motion perception.

Examined the effects of spatially directed attention on the temporal characteristics of information transmission in the visual system. A 2-stimulus, 2-flash, long-range motion display was used. The results showed that attending to 1 of the 2 stimuli altered the perceived direction of motion, the pattern of motion and no-motion responses, and ratings of motion quality. The results were compared with predictions derived from 2 conceptual frameworks of attention: a temporal-profile model and an additive account. The results support the temporal-profile model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of vestibular and visual motion perception on task performance

The effects of foveal and peripheral visual, as well as vestibular, cues on the performance and control behaviour of subjects in two different roll control tasks were studied in a moving base flight simulator with low noise motion characteristics. Two different roll control tasks were used, one being a following task (or compensatory tracking task) where a displayed random signal was to be tracked, the other being a disturbance task in which a random signal perturbed the controlled system and the roll angle was to be kept at zero. Consistent improvement in controller performance was found after adding visual peripheral or vestibular (motion) cues to the basic configuration consisting of a central CRT display. Control behaviour, as expressed by controller transfer functions was also markedly influenced by the addition of these extra motion cues, the changes in control behaviour being dependent on the type of control task. Some possible causes for this dependence are discussed.     

Gibson's inspired but latent prelude to visual motion perception.

J. J. Gibson's (see PA, Vol 29:5103; see also PA, Vol 81:28168) article is paradoxical: This forward-looking review of visual motion perception anticipates developments in the field, yet those developments were achieved without closely following Gibson's footsteps. This commentary offers several possible reasons for the dormancy of Gibson's ideas about motion perception and evaluates contemporary work on motion perception in the context of Gibson's perspective. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The visual perception of objective motion and subjective movement.

(This reprinted article originally appeared in Psychological Review, 1954, Vol 61, 304–314. The following abstract of the original article appeared in PA, Vol 29:5103.) The question of movement involves at least 3 closely related questions: How do we see the motion of an object? How do we see the stability of the environment? How do we perceive ourselves as moving in a stable environment? The author draws together the experimental evidence on the 3 questions and draws out its implications, including a hypothesis for research. The article concludes with a discussion of the requirements for a psychophysics of kinetic impressions. 19 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact visual imagery and impaired visual perception in a patient with visual agnosia.

Although it is now well accepted that visual mental imagery and visual perception share common underlying mechanisms, there are several reports in which they are dissociated. Evidence for the separability of these processes is provided by a 33-yr-old male patient who has a profound visual object recognition deficit attributable to an impairment in grouping or segmenting visual images. Despite this perceptual deficit, the patient was able to draw objects in considerable detail from memory, and his knowledge of the visual appearance of objects was preserved on a variety of mental imagery tasks. Together with previous cases, these findings confirm the double dissociation between object recognition and perception. Interestingly, the patient could also recognize newly constructed objects in his internal imagery. To accommodate these results, the authors propose a model in which imagery and perception are strongly associated but are also functionally specialized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object manipulation and motion perception: Evidence of an influence of action planning on visual processing.

In 3 experiments, the authors investigated the bidirectional coupling of perception and action in the context of object manipulations and motion perception. Participants prepared to grasp an X-shaped object along one of its 2 diagonals and to rotate it in a clockwise- or a counterclockwise direction. Action execution had to be delayed until the appearance of a visual go signal, which induced an apparent rotational motion in either a clockwise- or a counterclockwise direction. Stimulus detection was faster when the direction of the induced apparent motion was consistent with the direction of the concurrently intended manual object rotation. Responses to action-consistent motions were also faster when the participants prepared the manipulation actions but signaled their stimulus detections with another motor effector (i.e., with a foot response). Taken together, the present study demonstrates a motor-visual priming effect of prepared object manipulations on visual motion perception, indicating a bidirectional functional link between action and perception beyond object-related visuomotor associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual motion perception after brain damage: II. Deficits in form-from-motion perception

We investigated form-from-motion perception (FFM perception) in a sample of 39 patients with acquired brain damage. Pronounced FFM deficits were found in two patients (FM1 and FM2) with biparietal lesions. Both patients were able to identify the relevant figure, when it was not embedded in obstructive texture. Moreover, they could localize the figures in the FFM condition, although they could not reliably identify them. The two patients had normal motion coherence thresholds. Their performance in a static figure-ground task did not differ from that of other patients. These findings imply that the FFM deficits are not caused by impairment of basic visual motion or form perception but are the consequence of damage to a parietal brain structure involved in the combined analysis of visual motion and form information. The nature and functional role of this brain structure as well as the implications of our results for models of FFM perception are discussed.     

Taking a long look at action and time perception.

Everyone has probably experienced chronostasis, an illusion of time that can cause a clock's second hand to appear to stand still during an eye movement. Though the illusion was initially thought to reflect a mechanism for preserving perceptual continuity during eye movements, an alternative hypothesis has been advanced that overestimation of time might be a general effect of any action. Contrary to both of these hypotheses, the experiments reported here suggest that distortions of time perception related to an eye movement are not distinct from temporal distortions for other kinds of responses. Moreover, voluntary action is neither necessary nor sufficient for overestimation effects. These results lead to a new interpretation of chronostasis based on the role of attention and memory in time estimation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Binocular visual surface perception

Binocular disparity, the differential angular separation between pairs of image points in the two eyes, is the well-recognized basis for binocular distance perception. Without denying disparity's role in perceiving depth, we describe two perceptual phenomena, which indicate that a wider view of binocular vision is warranted. First, we show that disparity can play a critical role in two-dimensional perception by determining whether separate image fragments should be grouped as part of a single surface or segregated as parts of separate surfaces. Second, we show that stereoscopic vision is not limited to the registration and interpretation of binocular disparity but that it relies on half-occluded points, visible to one eye and not the other, to determine the layout and transparency of surfaces. Because these half-visible points are coded by neurons carrying eye-of-origin information, we suggest that the perception of these surface properties depends on neural activity available at visual cortical area V1.     

Neural systems shared by visual imagery and visual perception: a positron emission tomography study

Subjects participated in perceptual and imagery tasks while their brains were scanned using positron emission tomography. In the perceptual conditions, subjects judged whether names were appropriate for pictures. In one condition, the objects were pictured from canonical perspectives and could be recognized at first glance; in the other, the objects were pictured from noncanonical perspectives and were not immediately recognizable. In this second condition, we assume that top-down processing is used to evaluate the names. In the imagery conditions, subjects saw a grid with a single X mark; a lowercase letter was presented before the grid. In the baseline condition, they simply responded when they saw the stimulus, whereas in the imagery condition they visualized the corresponding block letter in the grid and decided whether it would have covered the X if it were physically present. Fourteen areas were activated in common by both tasks, only 1 of which may not be involved in visual processing (the precentral gyrus); in addition, 2 were activated in perception but not imagery, and 5 were activated in imagery but not perception. Thus, two-thirds of the activated areas were activated in common.     

Don't look down: Emotional arousal elevates height perception.

In a series of experiments, it was found that emotional arousal can influence height perception. In Experiment 1, participants viewed either arousing or nonarousing images before estimating the height of a 2-story balcony and the size of a target on the ground below the balcony. People who viewed arousing images overestimated height and target size more than did those who viewed nonarousing images. However, in Experiment 2, estimates of horizontal distances were not influenced by emotional arousal. In Experiment 3, both valence and arousal cues were manipulated, and it was found that arousal, but not valence, moderated height perception. In Experiment 4, participants either up-regulated or down-regulated their emotional experience while viewing emotionally arousing images, and a control group simply viewed the arousing images. Those participants who up-regulated their emotional experience overestimated height more than did the control or down-regulated participants. In sum, emotional arousal influences estimates of height, and this influence can be moderated by emotion regulation strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Laterality in visual speech perception.

The lateralization of visual speech perception was examined in 3 experiments. Participants were presented with a realistic computer-animated face articulating 1 of 4 consonant-vowel syllables without sound. The face appeared at 1 of 5 locations in the visual field. The participants' task was to identify each test syllable. To prevent eye movement during the presentation of the face, participants had to carry out a fixation task simultaneously with the speechreading task. In one study, an eccentricity effect was found along with a small but significant difference in favor of the right visual field (left hemisphere). The same results were found with the face articulating nonlinguistic mouth movements (e.g., kiss). These results suggest that the left-hemisphere advantage is based on the processing of dynamic visual information rather than on the extraction of linguistic significance from facial movements. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Attentional episodes in visual perception.

Is one's temporal perception of the world truly as seamless as it appears? This article presents a computationally motivated theory suggesting that visual attention samples information from temporal episodes (episodic simultaneous type/serial token model; Wyble, Bowman, & Nieuwenstein, 2009). Breaks between these episodes are punctuated by periods of suppressed attention, better known as the attentional blink (Raymond, Shapiro, & Arnell, 1992). We test predictions from this model and demonstrate that participants were able to report more letters from a sequence of 4 targets presented in a dense temporal cluster than from a sequence of 4 targets interleaved with nontargets. However, this superior report accuracy comes at a cost in impaired temporal order perception. Further experiments explore the dynamics of multiple episodes and the boundary conditions that trigger episodic breaks. Finally, we contrast the importance of attentional control, limited resources, and memory capacity constructs in the model. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Anomalies of motion perception in infantile esotropia

PURPOSE: To quantify motion sensitivity in patients with infantile esotropia who, as a subgroup, have been previously reported to have abnormal oculomotor control. In addition, to probe abnormal binocular development as a factor underlying abnormal motion perception in infantile esotropia (IE), motion sensitivity was compared among participants with and without stereopsis. METHODS: Monocular sensitivity to leftward and rightward motion was assessed across the horizontal meridian, using partially coherent random dot kinematograms. Participants included 11 observers with IE, 5 observers with acquired esotropia, and 11 observers with normal eye alignment. RESULTS: Participants with IE showed no deficits in motion sensitivity to any visual field locations when motion thresholds were collapsed across direction. However, they showed an abnormal variation in directional anisotropy. Although sensitivity to centripetal motion was superior in both hemifields of control participants and in the temporal hemifields of participants with IE, a centrifugal bias was revealed in the nasal hemifields of IE. Stereoblind observers with acquired esotropia showed a normal centripetal directional anisotropy, whereas binocular observers with acquired esotropia showed directional anisotropy similar to that in the IE group. CONCLUSIONS: Motion perception, like oculomotor function in IE, is characterized by a variation of directional anisotropy for stimuli presented to the nasal hemifields. This finding supports the hypothesis that abnormal oculomotor control and motion perception in IE reflect a common disruption of the visual system. A similar variation of directional sensitivity in patients with acquired esotropia with normal stereopsis suggests that the interruption of binocularity is not the underlying cause of abnormal motion perception in IE.     

Memory for visual motion

Observers briefly viewed random dots moving in a given direction and subsequently recalled that direction. When required to remember a single direction, observers performed accurately for memory intervals of up to 8 s; this high-fidelity memory for motion was maintained when observers executed a vigilance task during the memory interval. When observers tried to remember multiple directions of motion, performance deteriorated with increasing number of directions. Still, memory for multiple directions was unchanged over delays of up to 30 s. In a forced-choice experiment, observers viewed 2 successive animation sequences separated by a memory interval; for both sequences, dots moved in any direction within a limited bandwidth. Observers accurately judged which animation sequence was more coherent, even with memory intervals of 30 s. The findings are considered within the context of cognitive bias and memory for other aspects of perception.     

Functional segregation of color and motion perception examined in motion nulling

We examine two hypotheses about the functional segregation of color and motion perception, using a motion nulling task. The most common interpretation of functional segregation, that motion perception depends only on one of the three dimensions of color, is rejected. We propose and test an alternative formulation of functional segregation: that motion perception depends on a univariate motion signal driven by all three color dimensions, and that the motion signal is determined by the product of the stimulus contrast and a term that depends only on the relative cone excitations. Two predictions of this model are confirmed. First, motion nulling is transitive: when two stimuli null a third they also null another. Second, motion nulling is homogeneous: if two stimuli null one another, they continue to null one another when their contrasts are scaled equally. We describe how to apply our formulation of functional segregation to other behavioral and physiological measurements.