Vector analysis and process combinations in motion perception: A reply to Wallach, Becklen, and Nitzberg (1985).

Comments on a proposed alternative to the present author's theory of perceptual vector analysis in motion perception, which was advanced by H. Wallach et al (see record 1986-00251-001). It is argued that Wallach et al have not taken the qualitative difference between their theory and vector analysis into account and that they employed an early and outdated vector theory in their study. Therefore, the conclusion by Wallach et al that their theory is superior to vector analysis is unwarranted. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learned stimulation in space and motion perception.

Argues that in the perception of distance, depth, and visual motion, a single property is often represented by 2 or more stimuli. Two instances of such redundant stimulation are discussed: (a) the various stimuli that represent visual motion and (b) the 2 forms of stimulation by which binocular parallax evokes stereoscopic depth perception. In the case of visual motion, simultaneous operation of redundant stimulation has raised questions concerning the basis of experienced motion and the conditions under which different motion processes are combined. Experiments are described that suggest that some redundant stimuli owe their existence to simple associative learning. Evidence is reviewed that shows that binocular parallax causes stereoscopic depth by means of 2 different perceptual processes. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depth perception in motion parallax and stereokinesis.

Perceived depth in the stereokinetic effect (SKE) illusion and in the monocular derivation of depth from motion parallax were compared. Motion parallax gradients of velocity can be decomposed into 2 components: object- and observer-relative transformations. SKE displays present only the object-relative component. Observers were asked to estimate the magnitude and near–far order of depth in motion parallax and SKE displays. Monocular derivation of depth magnitude from motion parallax is fully accounted for by the perceptual response to the SKE, and observer-relative transformations absent in the SKE are of perceptual utility only as determinants of the near–far signing of perceived sequential depth. The amount of depth and rigidity perceived in motion parallax and SKE displays covaries with the projective size of the stimuli. The monocular derivation of depth from motion is mediated by a perceptual heuristic of which the SKE is symptomatic. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Models of stimulus uncertainty in motion perception.

Proposed a model to account for the loss in visibility of moving targets that occurs when an observer is uncertain about the target's direction of motion. In response to uncertainty about 2 possible directions of motion, the observer is assumed to use a mechanism whose peak sensitivity is to a direction midway between the 2 possible directions. Seven experiments (observers were 7 naive Ss and the 1st author), using both reaction time and forced-choice data, demonstrate the predictive advantages of this midway model over competing single-band and multiple-band models. The experiments reveal several new properties of human motion perception: (a) direction and velocity information have orthogonal representations in the visual system; (b) although motion sensitivity does not vary with direction, the precision with which small changes in direction can be recognized does, reflecting differential breadth of tuning for directionally selective mechanisms sensitive to various directions; and (c) motion-analyzing mechanisms are broadly tuned for direction as well as speed. (47 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The figure ground problem in motion perception.

Perceiving motion in an object involves discriminating the object from its background, judging the motion contrast between figure and ground and then attributing the motion to the appropriate entity. The present paper discusses psychophysical data on Induced Motion (IM) which supports the view that object/motion perception is constructed relatively late in the system by combining the output of several different motion analysers. Results from two experiments suggest that solution of the figure ground problem in motion perception may occur late in processing, be mediated by the parvocelluar stream and involve combining the output of at least two types of motion analysers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The perception of depth through motion.

Motion perspective is the phenomenon that as an object moves, the projections of its surface features and of its contours undergo certain regular transformations. The retinal image undergoes similar transformations. This aspect of depth perception has received comparatively little attention. Theory has been primarily based on gestalt formulations, and, more recently, an empirical approach has been suggested which is based on the use of high speed computers. The latter approach appears quite promising. (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.     

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)     

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)     

Image statistics and the perception of apparent motion.

The short- and long-range apparent motion processes are discussed in terms of the statistical properties of images. It is argued that the short-range process, exemplified by the random-dot kinematogram, is primarily sensitive to the dipole statistics, whereas the long-range process, exemplified by illusory occlusion, is treated by the visual system primarily in terms of the tripole and higher statistical correlation functions. The studies incorporate the balanced dot, which is a unique stimulus element that permits high pass filtering while preserving detailed positional information. Low spatial frequencies are shown to be critical for texture segregation in random-dot kinematograms, independent of the grain size or number density of texture elements. Illusory path perception in the long-range process is shown not to require low spatial frequencies, but is sensitive rather to global temporal phase coherency. These results are interpreted in terms of the respective roles of the power and phase spectra in perceptual organization. The construction of balanced dots is discussed in detail. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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.     

Orientation-dependent priming effects in the perception of biological motion.

In a serial 2-choice reaction time (RT) task, Ss discriminated between a biological motion walker and a similar distractor. The point-light walker appeared in 1 of 2 possible in-depth orientations: The figure was walking either to the right or to the left in the sagittal plane. Reliable priming effects were established in consecutive trials but only when priming and primed walkers had the same in-depth orientation. This orientation-dependent priming effect was not tempered when priming and primed figures had different directions of articulatory motion (Exps 1–6), different starting positions in the step cycle (Exp 2), different point-light localizations (Exp 3), or when the figures were translating (Exps 4–6). The data converge with neurophysiological findings that suggest that object recognition is accomplished by accessing high-level, orientation-dependent representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Configural processing in the perception of apparent biological motion.

In classic demonstrations of apparent motion, observers typically report seeing motion along the shortest possible path between 2 sequentially presented objects. However, when realistic photographs of a human body are sequentially presented at slow temporal rates, observers report paths of apparent motion that arc consistent with the movement limitations of the human body even when those paths are not the shortest possible. The current set of experiments examined those aspects of the human form that lead to the perception of biomechanically consistent paths of motion. The authors' findings suggest that the perception of apparent biological motion extends to human movements that involve inanimate objects. The authors also report that observers can perceive apparent motion of nonbiological objects in a manner similar to apparent motion of human bodies. However, a global hierarchy of orientation and position cues resembling the human form is required for the perception of these paths. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accuracy and precision of binocular 3-D motion perception.

In principle, information for 3-D motion perception is provided by the differences in position and motion between left- and right-eye images of the world. It is known that observers can precisely judge between different 3-D motion trajectories, but the accuracy of binocular 3-D motion perception has not been studied. The authors measured the accuracy of 3-D motion perception. In 4 different tasks, observers were inaccurate, overestimating trajectory angle, despite consistently choosing similar angles (high precision). Errors did not vary consistently with target distance, as would be expected had inaccuracy been due to misestimates of viewing distance. Observers appeared to rely strongly on the lateral position of the target, almost to the exclusion of the use of depth information. For the present tasks, these data suggest that neither an accurate estimate of 3-D motion direction nor one of passing distance can be obtained using only binocular cues to motion in depth. (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)     

Object and observer motion in the perception of objects by infants.

Sixteen-week-old human infants distinguish optical displacements given by their own motion from displacements given by moving objects, and they use only the latter to perceive the unity of partly occluded objects. Optical changes produced by moving the observer around a stationary object produced attentional levels characteristic of stationary observers viewing stationary displays and much lower than those shown by stationary observers viewing moving displays. Real displacements of an object with no subject-relative displacement, produced by moving an object so as to maintain a constant relation to the moving observer, evoked attentional levels that were higher than with stationary displays and more characteristic of attention to moving displays, a finding suggesting detection of the real motion. Previously reported abilities of infants to perceive the unity of partly occluded objects from motion information were found to depend on real object motion rather than on optical displacements in general. The results suggest that object perception depends on registration of the motions of surfaces in the three-dimensional layout. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

机械镀锌过程中锌粉的受力及运动分析

采用粒径0.1-8.0μm范围的金属锌粉,在室温下以机械镀方式形成锌镀层。对镀桶内物质运动状态、机械碰撞力及锌粉颗粒之间的相互作用力进行了分析计算。结果表明：表面张力、液桥作用力和气泡团聚力是引起锌粉颗粒聚团的主要原因;分子间作用力、双电层作用力和溶剂化膜作用力对锌粉颗粒的聚团作用影响甚微。锌粉的紧实变形和镶嵌成层主要依靠机械碰撞力。     

Global and local precedence: Selective attention in form and motion perception.

Five experiments traced the causes of the discrepancy in research that showed both local and global precedence in selective attention tasks. The effects of the relative discriminabilities of the local and global levels of the stimuli and the differences between Stroop-type interference (attributable to incongruity on the irrelevant dimension) and Garner-type interference (attributable to variability on the irrelevant dimension) were explored. The experiments also examined whether the precedence effects previously examined in form perception generalize to motion perception. 45 Ss, most of whom were college students, participated. Ss viewed stimuli on an oscilloscope under 9 conditions. Results show that (a) some cases of global precedence were due solely to the greater perceptual discriminability of the global level; (b) instances of both local and global precedence could be demonstrated for certain types of stimuli, even when the discriminabilities of their local and global levels had been equated; and (c) the Stroop and Garner measures of selective attention were not equivalent but instead measured different types of interference. It is concluded that cases of both local and global precedence have been amply documented but that no general theory can account for why or when these effects will appear until a better understanding is gained of both the nature of part–whole relationships and the perceptual processes that are tapped by different measures of selective attention. (31 ref) (PsycINFO Database Record (c) 2010 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.     

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)