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PubMed2000

Orientation specificity in biological motion perception.

We addressed the issue of how display orientation affects the perception of biological motion. In Experiment 1, spontaneous recognition of a point-light walker improved abruptly with image-plane display rotation from inverted to upright orientation. Within a range of orientations from 180 degrees to 90 degrees, it was dramatically impeded. Using ROC analysis, we showed (Experiments 2 and 3) that despite prior familiarization with a point-light figure at all orientations, its detectability within a mask decreased with a change in orientation from upright to a range of 90 degrees-180 degrees. In Experiment 4, a priming effect in biological motion was observed only if a prime corresponded to a range of deviations from upright orientation within which the display was spontaneously recognizable. The findings indicate that display orientation nonmonotonically affects the perception of biological motion. Moreover, top-down influence on the perception of biological motion is limited by display orientation.

Adolescent↗
PubMed1998

[A study of motion perception in primary open-angle glaucoma].

OBJECTIVE: To study the characteristics of the motion perception (MP) in primary open-angle glaucoma (POAG). METHOD: Forty-one patients with POAG (67 eyes) and 56 (112 eyes) normal subjects were examined by the motion perception (MP) software in PC compatible computer. RESULTS: The total abnormal rate of MP was 89.5% in POAG, and 81.6% in the early stage of POAG. By using the grade correlation analysis, there is positive correlation of the abnormal degree of MP with C/D, ocular tension, and corrected loss variance (CLV) of visualfield, negative correlation of the abnormal degree of MP with visual acuity and visualfield mean sensitivity (MS), and no correlation of the abnormal degree of MP with age and short-term fluctuation (SF) of visualfield in the POAG patients. CONCLUSION: The examination of MP is a newly reliable and simple test for the diagnosis of the early POAG.

Adolescent↗
PubMed1992

Motion perception and aging.

The authors used a correlated motion paradigm to investigate the effects of aging and gender on motion sensitivity. In 2 experiments with a total of 50 elderly and 50 young subjects, motion thresholds were significantly higher for elderly women. The correlated motion signal, which was embedded in random motion, may have been coherent to subjects in much the same way a form is in Witkin's Embedded Figures Test (EFT). In Experiment 2, EFT scores were obtained. A significant positive relationship between motion thresholds and EFT performance was found within each age group. Although gender-related perceptual style differences may contribute to motion perception effects, the authors argue that a common neural factor contributes to performance on both the EFT and the correlated motion task.

Adult↗
PubMed1990

Intact "biological motion" and "structure from motion" perception in a patient with impaired motion mechanisms: a case study.

A series of psychophysical tests examining early and later aspects of image-motion processing were conducted in a patient with bilateral lesions involving the posterior visual pathways, affecting the lateral parietal-temporal-occipital cortex and the underlying white matter (as shown by magnetic resonance imaging studies and confirmed by neuro-ophthalmological and neuropsychological examinations). Visual acuity, form discrimination, color, and contrast-sensitivity discrimination were normal whereas spatial localization, line bisection, depth, and binocular stereopsis were severely impaired. Performance on early motion tasks was very poor. These include seeing coherent motion in random noise (Newsome & Paré, 1988), speed discrimination, and seeing two-dimensional form from relative speed of motion. However, on higher-order motion tasks the patient was able to identify actions from the evolving pattern of dots placed at the joints of a human actor (Johansson, 1973) as well as discriminating three-dimensional structure of a cylinder from motion in a dynamic random-dot field. The pattern of these results is at odds with the hypothesis that precise metrical comparison of early motion measurements is necessary for higher-order "structure from motion" tasks.

Cerebral Cortex↗
PubMed2006

Motion perception in migraineurs: abnormalities are not related to attention.

Migraine groups have impaired ability to identify global motion direction in noisy random dot stimuli, an observation that has been used as evidence for cortical hyperexcitability. Several studies have also suggested abnormalities in cognitive processing, particularly in the domains of attention, visuo-spatial processing and memory. This study aimed to determine whether poor performance by migraineurs in motion coherence tasks could be explained by non-visual cognitive factors such as attention. Twenty-nine migraineurs and 27 non-headache controls participated. Global motion coherence thresholds were measured along with measures of neuropsychological function, using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The migraine group had significantly higher motion coherence thresholds than controls. No significant difference in attention or any other RBANS index score was found between groups. Index scores did not correlate with motion perception thresholds. This study does not support inattention or other cognitive abnormality as an explanation for motion perception anomalies in migraine.

Adult↗
PubMed1993

Spatio-temporal characteristics of human motion perception.

A bi-local detector array model was assumed to describe the functional performance of monocular motion perception. Distributions of model parameters were measured in human vision at several positions in the visual field. The stimulus paradigm was designed to measure directional motion perception thresholds for individual combinations of spatial displacement and temporal delay in random dot apparent motion stimuli. The resulting data support previous results on perceivable spatial displacement limits in human vision but also indicate that both minimum and maximum perceivable spatial displacement thresholds in human observers have a similar dependence on temporal delay. This dependence changes with eccentricity in the visual field in a qualitatively similar manner but by quantitatively different factors. A description of possible biological properties of the bi-local detector population is presented that may explain how detection of spatio-temporal pattern displacements can be performed by a single system. Such a system also predicts that minimum and maximum perceivable spatial displacement thresholds should scale with visual field eccentricity in a manner consistent with our results.

Humans↗
PubMed1994

Motion perception. Moving on the surface.

Recent studies of motion perception show that, in the brain's internal representation of three-dimensional space, distances may be less important than relationships to surfaces.

Brain↗
PubMed2004

Non-invasive evaluation of face and motion perception in humans.

The neural mechanisms for the perception of face and motion were studied using psychophysical threshold measurements, event-related potentials (ERPs), and functional magnetic resonance imaging (fMRI). A face-specific ERP component, N170, was recorded over the posterior temporal cortex. Removal of the high-spatial-frequency components of the face altered the perception of familiar faces significantly, and familiarity can facilitate the cortico-cortical processing of facial perceptions. Similarly, the high-spatial-frequency components of the face seemed to be crucial for the recognition of facial expressions. Aging and visuospatial impairments affected motion perception significantly. Two distinct components of motion ERPs, N170 and P200, were recorded over the parietal region. The former was related to horizontal motion perception while the latter reflected the perception of radial optic flow motion. The results of fMRI showed that horizontal movements of objects and radial optic flow motion were perceived differently in the V5/MT and superior parietal lobe. We conclude that an integrated approach can provide useful information on spatial and temporal processing of face and motion non-invasively.

Cognition Disorders↗
PubMed2005

Theory of mind and motion perception in schizophrenia.

This study investigated the relationship between theory of mind (ToM) deficits and visual perception in patients with schizophrenia (N=52; 17 remitted and unmedicated) compared with healthy controls (N=30). ToM was assessed with the Eyes Test, which asked participants to choose which of 4 words best described the mental state of a person whose eyes were depicted in a photograph. Visual perception was evaluated with form and motion coherence threshold measurements. Results revealed that patients with schizophrenia (both remitted and nonremitted) showed deficits on the Eyes Test and the motion coherence task. ToM dysfunctions were associated with higher motion coherence thresholds and more severe negative symptoms. This suggests that ToM deficits are related to motion perception dysfunctions, which indicates a possible role of motion-sensitive areas in the pathophysiology of schizophrenia.

Adult↗
PubMed1991

Does primate motion perception depend on the magnocellular pathway?

This study examined the importance of the primate magnocellular retinocortical pathway in the perception of moving stimuli. A portion of the magnocellular pathway was permanently and selectively interrupted by ibotenic acid injections in the LGN of macaque monkeys. We then tested contrast sensitivity for detecting moving stimuli, as well as two indices of motion perception, contrast sensitivity for opposite direction discrimination and speed difference thresholds, in the affected portion of the visual field. Magnocellular lesions greatly reduced detection contrast sensitivity at high temporal and low spatial frequencies and had a similar effect on contrast sensitivity for opposite direction discrimination under these same stimulus conditions. Consequently, opposite direction discriminations could be made at contrast threshold, suggesting that magnocellular lesions reduced the visibility of stimuli used to test direction perception, but did not act directly on direction perception. Magnocellular lesions also elevated speed difference thresholds under some stimulus conditions. However, this deficit was reduced or eliminated by raising the contrast of the test stimulus. Together, these findings suggest that magnocellular lesions reduce the visibility of stimuli used to test motion perception but that they do not appear to alter motion perception otherwise.

Animals↗
PubMed1997

Isoluminance and chromatic motion perception throughout the visual field.

Isoluminance and chromatic motion perception for red/green gratings were measured throughout an 80 deg visual field. Generally, the red/green isoluminance values changed with increasing eccentricity, i.e., observers increased the red luminance contrast for a fixed green luminance contrast. Enlarging the target size (to compensate for the cone density changes with eccentricity) and decreasing the spatial frequency (to compensate for receptive field property changes with eccentricity) did not change the isoluminance values within the central 20 deg, but the isoluminance ratios decreased beyond 20 deg. Our manipulations did not entirely compensate for a given eccentricity, which implies the need for a post-receptoral scaling function for the perception of drifting chromatic stimuli. Further, the results for isoluminance show heterogeneity between the visual field meridians where the red to green luminance ratio tends to be greater in the superior visual field. In our present conditions, chromatic motion was always perceived (up to 40 deg of eccentricity), but sensitivity generally decreased with increasing eccentricity. The inferior visual field was found to be the most sensitive to chromatic motion. We propose that the lower visual field and not the superior visual field is specialized for colour motion information.

Color Perception↗
PubMed1994

Neural network approaches to visual motion perception.

This paper concerns certain difficult problems in image processing and perception: neurocomputation of visual motion information. The first part of this paper deals with the spatial physiological integration by the figure-ground discrimination neural network in the visual system of the fly. We have outlined the fundamental organization and algorithms of this neural network, and mainly concentrated on the results of computer simulations of spatial physiological integration. It has been shown that the gain control mechanism, the nonlinearity of synaptic transmission characteristic, the interaction between the two eyes, and the directional selectivity of the pool cells play decisive roles in the spatial physiological integration. In the second part, we have presented a self-organizing neural network for the perception of visual motion by using a retinotopic array of Reichardt's motion detectors and Kohonen's self-organizing maps. It has been demonstrated by computer simulations that the network is able to learn to solve the ambiguities given by local motion detection mechanism. The resultant self-organized configuration in the output layer is resembling direction selective columns which first appear in area MT of the primate visual system. It has been explored that the spatio-temporal coherences, mapping, cooperation, competition, and Hebb rule are the basic neural principles for visual motion perception.

Animals↗
PubMed1993

Motion perception with spatiotemporally matched chromatic and achromatic information reveals a "slow" and a "fast" motion system.

Recent reports dealing with apparent motion challenged the standard view according to which motion processing should be impossible if the visual attributes matched across space and time are processed in independent channels (the similarity principle). The present work examines this possibility insofar as it relates to the spatiotemporal combination of pure chromatic and pure luminance information. The data indicate that the "similarity principle" is indeed infringed at low (< or = 2.5 Hz, i.e. velocities of 2.5 deg/sec for spatial modulations of 1 c/deg, in this study) but not at high (> or = 7.5 Hz) temporal frequencies. The fact that colour and luminance may or may not combine to yield motion perception depending on their temporal modulation reconciliates contradictory results in the literature and supports the idea of two motion systems, a "fast"/specific one, integrating information only from similar subunits, and a "slow"/unspecific one, integrating information across dissimilar subunits (in the present case, across the chromatic and achromatic "domains"). This dichotomy is also supported by the finding that chromatic reverse-phi (i.e. with equiluminant, red and green stimuli) can be observed at medium temporal frequencies but is replaced by direct motion at low temporal frequencies, presumably within the range of the "slow"/unspecific system. Using a modified "minimum motion" technique (referred to as the Reverse-Phi equiluminance method) we present data allowing to assess the relative weights of the two systems as a function of temporal frequency.

Color Perception↗
PubMed1998

Complex motion perception and its deficits.

Within the hierarchy of motion perception, the dorsolateral middle superior temporal area (MSTd) is optimally suited for the analysis of the complex motion patterns that are directly useful for visually guided behaviour (e.g. computation of heading). Recent electrophysiological and psychophysical evidence suggests the existence of 'detectors' in MSTd that are specialised for complex motion patterns and advocates the necessity of combining retinal and extraretinal signals received by MSTd neurones for the accurate perception of heading. In some neurological patients, of which only a small number have been reported to date, lesions involving the human homologue of MST have devastating effects on their ability to navigate in their surroundings. It has been reported that these patients have impaired performance of psychophysical tasks of complex motion discrimination.

Animals↗
PubMed1990

Assimilation and contrast in motion perception: explorations in cooperativity.

Motions within one region of the field influence motion seen elsewhere. To explore this phenomenon we used cinematograms comprised of alternating strips within which dots (i) tended to move in one direction, or (ii) moved in random directions (dynamic noise). When alternating strips were narrow, motion in one direction induced a similar direction of illusory motion in the adjoining dynamic noise (assimilation); when alternating strips were wide, motion tended to induce an illusory opposed motion in the dynamic noise (contrast). Since this illusory motion exhibits hysteresis, it probably results from spatially distributed, cooperative processes. The shift from assimilation to contrast, as the cinematogram's strips increase in size, suggests that facilitatory and inhibitory influences of the network extend over different distances.

Contrast Sensitivity↗
PubMed1995

Visual motion perception.

The primate visual motion system performs numerous functions essential for survival in a dynamic visual world. Prominent among these functions is the ability to recover and represent the trajectories of objects in a form that facilitates behavioral responses to those movements. The first step toward this goal, which consists of detecting the displacement of retinal image features, has been studied for many years in both psychophysical and neurobiological experiments. Evidence indicates that achievement of this step is computationally straightforward and occurs at the earliest cortical stage. The second step involves the selective integration of retinal motion signals according to the object of origin. Realization of this step is computationally demanding, as the solution is formally underconstrained. It must rely--by definition--upon utilization of retinal cues that are indicative of the spatial relationships within and between objects in the visual scene. Psychophysical experiments have documented this dependence and suggested mechanisms by which it may be achieved. Neurophysiological experiments have provided evidence for a neural substrate that may underlie this selective motion signal integration. Together they paint a coherent portrait of the means by which retinal image motion gives rise to our perceptual experience of moving objects.

Animals↗
PubMed2003

Compound self-motion perception induced by two kinds of optical motion.

Two kinds of flow patterns consisting of random dots were presented simultaneously to subjects to investigate whether or not two kinds of vection occur simultaneously. One pattern induces vertical linear self-translation, whereas the other induces self-rotation around a vertical axis (when either pattern is presented alone). Three sets of conditions were tested. The first condition was one in which random dots moved in a summed direction of both flow vectors. In the second condition, both flow patterns were simply overlaid, whereas in the third condition, the two kinds of flow patterns were overlaid with a depth separation produced by binocular disparity. The subjects perceived both kinds of vection simultaneously in directions opposite to those of the corresponding flow components under the first condition, whereas either vection occurred mainly under the second condition. Under the third condition, both of the flows induced each kind of vection simultaneously, despite there being no physical vector summation of dot motion. The background flow induced vection in a direction opposite to the flow direction, whereas the foreground flow induced vection in the same direction as the flow direction. These results show that induced self-translation and induced self-rotation can occur simultaneously in two ways.

Humans↗
PubMed1993

Barber-pole illusions and plaids: the influence of aperture shape on motion perception.

The barber-pole illusion and its influence on plaid perception were investigated in two experiments to test the following expectations: (i) apertures which bias the perception of grating motion in directions consistent with plaid direction will facilitate plaid perception, and (ii) apertures which bias the perception of grating motion in directions inconsistent with plaid direction will disrupt plaid perception. In experiment 1 the barber-pole illusion was measured as a function of grating orientation (20 degrees, 45 degrees, and 70 degrees, clockwise and counterclockwise from horizontal), and aperture shape (vertical, horizontal; at each of three elongations). Barber-pole illusions reported with 45 degrees gratings increased with increased aperture elongation. However, this was not found with 20 degrees and 70 degrees gratings; these were almost always reported as moving in a direction parallel to the side of the aperture with which the gratings formed angles approaching 90 degrees. In experiment 2 this dependence of barber-pole illusions on the relative orientation between gratings and apertures was also evident with 45 degrees gratings in oblique apertures; only oblique directions of grating motion were reported. The influence of the same apertures on the separate contrast thresholds required for initial plaid coherence and initial plaid decomposition was measured. In experiments 1 and 2, coherence thresholds were unaffected by apertures, contrary to expectation (i). However, in both experiments expectation (ii) was confirmed; decomposition thresholds decreased in apertures which biased perceived direction of gratings towards vertical (plaid direction), and increased in apertures which biased grating motion away from vertical. Adaptation of plaid mechanisms during measurement of decomposition thresholds was proposed to explain the discrepancy between coherence and decomposition data. Taken together, the results were interpreted as reflecting interactions between mechanisms mediating the barber-pole illusion and mechanisms mediating plaid perception.

Humans↗