Constraints common to apparent motion in visual, tactile, and auditory space.

A point-like stimulus was presented in a clockwise or counterclockwise sequence at 3, 4, 6, or 12 uniformly spaced locations around a circle in visual, tactile, or auditory space. In 4 experiments, the simulators were (a) light-emitting diodes in the frontal plane, (b) mechanical stimulators on the palm, (c) airpuff nozzles around the head, and (d) loudspeakers around the head. For each spatial separation and stimulus-onset asynchrony (SOA) between successive stimuli around the circle, participants reported the direction of motion. Within each modality, the SOA required for 75% accurate discrimination of direction increased with the spatial separations. A time–distance constraint akin to Korte's third law of visual apparent motion can thus be obtained from responses that are objectively classifiable as correct or incorrect (without relying on subjective reports of "goodness" of apparent motion). Moreover, this time-distance constraint evidently generalizes across sensory modalities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation of short- and long-range apparent motion in visual search.

The visual search paradigm was used in four experiments to investigate apparent motion perception. The addition of distractor items led to a linear increase in reaction time (RT) under long-range (LR) conditions (>35 min of arc displacement), whereas RT was independent of display size under short-range (SR) conditions (     

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)     

Illusory line motion in visual search: attentional facilitation or apparent motion?

A line, presented instantaneously, is perceived to be drawn from one end when a dot is flashed at that end prior to the presentation of the line. Although this phenomenon, called illusory line motion, has been attributed to accelerated processing at the locus of attention, preattentive (stimulus-driven) motion mechanisms might also contribute to the line-motion sensation. We tested this possibility in an odd-target-search task. The stimulus display consisted of two, four, or eight pairs of dots and lines. All lines were presented on the same side of the dots (eg right), except for the target line, which was presented on the opposite side (left). Subjects were asked to report the presence or absence of the target, which was presented in half of the trials. Low error rates for target detection (about 10%) even when the display consisted of eight dot-line pairs (ie display size was eight) indicated that illusory line motion could be perceived simultaneously at many locations. The interstimulus interval (ISI) between the dots and lines (0-2176 ms) and the contrast polarity (both dots and lines were brighter than the background, or dots were darker and lines were brighter) were also manipulated. When an ISI of a few hundred milliseconds was inserted, target detection was nearly impossible with larger display sizes. When the contrast polarity was changed, the target-detection performance was impaired significantly, even with no ISI. Moreover, it was found that the effects of display size, ISI, and contrast polarity were comparable in searches for a two-dot apparent-motion target. These results support the idea that preattentive, apparent-motion mechanisms, as well as attentional mechanisms, contribute to illusory line motion.     

Object continuity in apparent motion and attention.

Presents 2 experiments that show that the continuity property may underlie 2 seemingly unrelated perceptual phenomena: attentional capture by abrupt visual onset and the appearance of bistable apparent motion displays. In Exp 1, 30 Ss reported the appearance of a bistable apparent-motion (or Ternus) display and engaged in visual search for a prespecified target; on each trial 1 element was briefly flickered off and back on. The time course of the gap duration effect in the visual search task was very similar to that for the Ternus display. In Exp 2, with 15 Ss, the possibility that the presence of an abrupt offset caused the results of Exp 1 was ruled out, since the reactions times (RTs) for the single- and double-offset conditions were similar. Results suggest that the interruption of spatiotemporal continuity may be the underlying mechanism that produces these 2 seemingly unrelated perceptual phenomena. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The two-process distinction in apparent motion.

Traces the historical development of the notion that two processes mediate apparent motion percepts, examines evidence regarding their existence, and summarizes associated characteristics. The short-range process is assumed to reflect the activity of low-level directionally selective motion detectors, have a relatively small spatial integration range, and be favored by short stimulus durations and interstimulus intervals. The long-range process is thought to reflect higher order perceptual activity, match stimulus elements over relatively large retinal distances, and be favored by longer stimulus durations and interstimulus intervals. Criteria for associating different percepts with functionally different processes are advanced and applied. The theoretical status of the two-process distinction is examined, and a heuristic model of motion perception is presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial attention and audiovisual interactions in apparent motion.

In this study, the authors combined the cross-modal dynamic capture task (involving the horizontal apparent movement of visual and auditory stimuli) with spatial cuing in the vertical dimension to investigate the role of spatial attention in cross-modal interactions during motion perception. Spatial attention was manipulated endogenously, either by means of a blocked design or by predictive peripheral cues, and exogenously by means of nonpredictive peripheral cues. The results of 3 experiments demonstrate a reduction in the magnitude of the cross-modal dynamic capture effect on cued trials compared with uncued trials. The introduction of neutral cues (Experiments 4 and 5) confirmed the existence of both attentional costs and benefits. This attention-related reduction in cross-modal dynamic capture was larger when a peripheral cue was used compared with when attention was oriented in a purely endogenous manner. In sum, the results suggest that spatial attention reduces illusory binding by facilitating the segregation of unimodal signals, thereby modulating audiovisual interactions in information processing. Thus, the effect of spatial attention occurs prior to or at the same time as cross-modal interactions involving motion information. (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)     

Age differences in visual search for feature, conjunction, and triple-conjunction targets.

The authors examined the ability of younger and older adults to search for targets defined by single features (feature search), conjunctions of 2 features (conjunction search), and conjunctions of 3 features (triple-conjunction search). Feature search was relatively age-invariant, with both older and younger adults displaying shallow search slopes. However, older adults did show reduced search rates for many conjunction targets. Interestingly, both older and younger adults benefited equivalently when an extra feature was available to define the conjunction target. That is, the relative amount of improvement in search performance was similar for younger and older adults when the triple-conjunction search was compared to the conjunction search. These results are discussed in terms of age-related differences in the effectiveness of bottom-up and top-down mechanisms that support visual search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A theory of visual information acquisition and visual memory with special application to intensity-duration trade-offs.

Describes a theory of memory for visual material in which the visual system acts as a linear filter operating on a stimulus to produce a function, a(t), relating some sensory response to t (the time since stimulus onset). Stimulus information is acquired at a rate proportional to the product of the magnitude by which a(t) exceeds some threshold, and the amount of as-yet-unacquired information. Recall performance is assumed to equal the proportion of acquired information. The theory accounts for data from 2 digit-recall experiments in which stimulus temporal waveform was manipulated. The authors comment on the theory's account of the relation between 2 perceptual events: the phenomenological experience of the stimulus, and the memory representation that accrues from stimulus presentation. It is asserted that these 2 events, although influenced by different variables, can be viewed as resulting from 2 characteristics of the same sensory-response function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bistability and hysteresis in the organization of apparent motion patterns.

In a paradigm for which 2 distinct patterns are perceived for the same stimulus, perceptual hysteresis (persistence of a percept despite parameter change to values favoring the alternative pattern) and temporal stability (persistence despite intrinsic propensities toward spontaneous change) are interdependent. Greater persistence during parameter change reduces temporal stability, slowing the rate of parameter change reduces hysteresis by increasing opportunity for spontaneous change, and increasing temporal stability (by enlarging the stimulus) increases hysteresis. Hysteresis results in the perception of parametrically disfavored patterns; a parameter can influence a percept without specifying it. The visual system thus exhibits time-dependent behavior analogous to dynamical behavior observed in other systems, both physical and biological, for which there is competition among alternative patterns that vary in relative stability. (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)     

Calibrating reach distance to visual targets.

The authors investigated the calibration of reach distance by gradually distorting the haptic feedback obtained when participants grasped visible target objects. The authors found that the modified relationship between visually specified distance and reach distance could be captured by a straight-line mapping function. Thus, the relation could be described using 2 parameters: bias and slope. The authors investigated whether calibration generalized across reach space with respect to changes in bias and slope. In Experiment 1, the authors showed that both bias and slope recalibrate. In Experiment 2, they tested the symmetries of reach space with respect to changes in bias. They discovered that reach space is asymmetric, with the bias shifting inward more readily than outward. The authors measured how rapidly the system calibrated and the stability of calibration once feedback was removed. In Experiment 3, they showed that bias and slope can be calibrated independently of one another. In Experiment 4, the authors showed that these calibration effects are not cognitively penetrable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Close binding of identity and location in visual feature perception.

The binding of identity and location information in disjunctive feature search was studied. 30 Ss searched a heterogeneous display for a color or a form target and reported both target identity and location. To avoid better than chance guessing of target identity (by choosing the target less likely to have been seen), the difficulty of the 2 targets was equalized adaptively; a mathematical model was used to quantify residual effects. A spatial layout was used that minimized postperceptual errors in reporting location. Results showed strong binding of identity and location perception. After correction for guessing, no perception of identity without location was found. A weak trend was found for accurate perception of target location without identity. The authors propose that activated features generate attention-calling "interrupt" signals, specifying only location; attention then retrieves the properties at that location. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pulfrich effect and the filling in of apparent motion

In the stroboscopic version of the Pulfrich effect a filter is able to induce depth shifts in a target as if the latter were moving continuously, rather than merely occupying a series of discrete positions. This was examined in a further series of experiments, in which a visual alignment technique was used to measure the perceived visual direction of an apparently moving target in intervals between its presentations. Results showed that the target has approximately the visual direction that it would have if it were moving continuously. This "filling in" of apparent motion was shown to occur before the level of stereopsis. The possible influence of tracking eye movements is discussed.     

Chronometric analysis of apparent spotlight failure in endogenous visual orienting.

Ss made speeded responses to peripheral luminance increments or decrements preceded by informative central precues. In 4 experiments with 48 university students, one of these stimuli was much more likely to occur than the other. In a simple detection task, the likely and unlikely stimuli showed equivalent cuing effects. In a discrimination task (bright/dim), the likely stimuli showed cuing but the unlikely one did not (spotlight failure), and there was a tendency to make the likely response when the unlikely stimulus occurred at the cued location. In Exp 5, the 2 stimuli were equally likely, and a choice was required. Large cuing effects were observed for both stimuli with no evidence of a speed–accuracy trade-off. A logogen-activation framework is described within which criterion and sensitivity adjustments are needed to accommodate the full pattern of results. Endogenous orienting appears to enhance processing of all stimuli at attended (relative to unattended) locations, an effect that may be masked by specific stimulus or response expectancies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Regulation of social contact in laboratory rats: Time, not distance.

Several studies have shown that rats regulate affiliative behavior, becoming more affiliative after social isolation and less affiliative after satiation. To determine if they regulate (a) time devoted to social activities or (b) distance between animals, both time and distance were measured in a 4-ft or 12-ft diameter circular open field. In an experiment involving 45 male hooded rats, it was found that (a) social distance varied with field size, but time in social contact did not; (b) Ss showed no propensity to keep any social distance other than zero; (c) noncontact distances were large, close to chance; and (d) time was more sensitive statistically than distance to variations in affiliative motivations. Thus, time was the critical dimension used to regulate affiliative encounters. Time may also be the dimension along which noncontact species regulate affiliation. (43 ref) (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)     

Age-related reduction in 3-D visual motion priming.

In 3 experiments, younger and older adults judged the perceived motion of three-dimensional (3-D) figures that rotated in depth either unambiguously or ambiguously. Both groups were found to be equivalent in judging the direction of single rotations of the simulated 3-D objects (Experiment 1). In Experiments 2 and 3, a single unambiguous rotation (prime) was followed 0-3200 ms later by an ambiguous rotation (target). Motion priming was indicated by the disambiguation of the second rotation by the first rotation. 3-D motion priming was initially found to be similar in young and old, but it rapidly reduced in the older participants compared to the younger ones. Using a nonluminance depth cue—occlusion—to induce 3-D motion, diminished contrast sensitivity in the elderly was ruled out as a cause of the reduced priming. The results show that 3-D motion priming exhibits robust age-related decline. An age-related decrease in temporal persistence may account for the reduction in 3-D motion priming in older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)