Binocular distance perception.

Binocular distance perception is not veridical. A constant binocular disparity corresponds neither to a constant perceived depth nor to a constant perceived distance ratio. Perceived relative distance depends on physical distance as well as disparity. This implies the existence of an egocentric distance signal. A model is proposed that attributes all of the error in binocular distance perception to a misperception of egocentric distance and a difference in the effective magnifications in the 2 eyes. Perceived distance of near targets exceeds physical distance; perceived distance of far targets is less than physical distance. The model describes a large body of data in which Ss set distances to satisfy various relative perceived distance criteria. The misperception of egocentric distance is also manifested in a variety of experiments in which the S directly indicates perceived egocentric distance. The egocentric distance signal appears to be of extraretinal origin and to be related to the vergence of the eyes. (59 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Binocular distance perception: Egocentric distance tasks.

Tested an extension of the present author's (1978; see also PA, Vol 64:11699) theory of binocular distance perception, which has been shown to give a good account of performance in relative distance tasks. In 2 experiments, 5 18–36 yr olds indicated perceived egocentric distance of targets (perceived distance from him/herself) by means of a verbal report or manual pointing response. In Exp I, the distance to 2 targets was varied while maintaining a constant disparity between them. In Exp II, 1 target was held fixed while the distance to a 2nd target was varied. In each case, Ss indicated the perceived distance of each target. Manual and verbal responses agreed with each other to within a linear transform. Both sets of data are consistent with the theory and indicate that reference parallax is a weighted average of target parallaxes. The systematic inaccuracy of binocular distance perception is attributed to the misperception of egocentric distance to the configuration. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual perception and aging.

Reviews a series of studies on aging and its effect on perceptual processing and working memory capacity for visual stimuli. Specifically, studies on luminance, color, motion, texture, and symmetry processing are reported. Furthermore, experiments on the capacity to retain size and spatial frequency information are also discussed. The general conclusion is that there are a number of perceptual abilities that diminish with age. However, the extent of these deficits will depend on the complexity of the neural circuitry involved for processing a given task. This is also true for visual working memory where no evidence of loss due to aging is demonstrated for processing low-level visual information, when individual differences in sensory input are compensated for. It is concluded that perceptual processing deficits due to aging (like working memory) will become evident when the computational load reaches a certain level of complexity (larger or more complex network) even if the tasks remain cognitively simple. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Monocular distance perception in schizophrenics.

This study was designed to investigate the possibility of a dysfunction in monocular depth perception in schizophrenics. 50 schizophrenics and 50 normals were asked to align monocularly viewed patterned and unpatterned projected images with each of 5 monocularly viewed, minimally lighted rods. An analysis of variance indicated a difference significant beyond the 1% level in the alignment ability of the 2 groups and stimulus intensification of the images with color increased both groups' alignment ability. A trend analysis indicated a significant increase in the difference between the groups from p     

Dynamic contrast perception assessed by pattern masking

The perceived contrast of a pulsed grating varies markedly with the exposure duration and spatial frequency of the grating. We studied dynamic changes in perceived grating contrast with a pattern-masking paradigm. We measured masking of a brief, localized test pattern (a D6 stimulus, 30 ms in duration) by fixed-contrast cosine grating patterns of varying duration (50-500 ms). The cosine mask pattern had spatial frequency of either 1 or 6 cycles per degree (cpd) at a contrast of 0.3. The D6 test pattern was centered on a light bar of the mask and was either positive peak contrast (same-polarity test and mask) or negative peak contrast (opposite-polarity test and mask). In Experiment 1, the test and mask had simultaneous onset. With a 6-cpd mask, the same-polarity test-threshold elevation versus mask-duration function increases monotonically. For a 1-cpd mask, the same-polarity threshold-mask-duration function is nonmonotonic, with peak masking effect produced by a grating pulse of 80-100 ms. These masking effects are closely congruent with known dynamic contrast effects. With negative tests, masking-duration functions are elevated from same-polarity functions and are essentially similar in shape for 1- and 6-cpd masks. The elevated thresholds suggest inhibitory interaction between ON and OFF pathways, with a similar time course across spatial frequency. In Experiment 2, the D6 test was delayed from mask onset by 33 ms. Positive contrasts only were employed. For 1-cpd stimuli, the delay of test greatly reduced masking at all mask durations and eliminated the nonmonotonic function. This suggests that for low-spatial-frequency patterns, perceived contrast is determined by an early peak component of the neural response. But for 6-cpd stimuli, masking of the delayed test was somewhat greater at all mask durations, consistent with a gradually increasing underlying neural response to the grating. Finally, in Experiment 3, same-polarity masking effects at both spatial frequencies were replicated with negative-contrast test and mask (OFF pathway mediation). This indicates that the ON and OFF pathways have similar response dynamics.     

Visual short-term memory is influenced by haptic perception.

The present study investigated whether and how visual memory and haptic perception are related. Participants were required to compare a visual reference velocity with a visual test velocity separated by a 4-s interval. During the retention interval, a fast or slow hand movement was performed. Although the hand movement was not visible, effects of the speed of the distracting body movement occurred. Slow movements resulted in a lowering of the represented visual velocity, whereas fast movements heightened the represented velocity. Subsequent experiments extended the effect to body movements that differed from the visual motion and ruled out the possibility that the effect was due to changes in visual perception or interference from semantic, verbal, and acoustic memory codes. Perhaps haptic velocity information and visual velocity information stored in short-term memory am blended. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of distance upon risk perception.

148 Ss were asked to rate the hazard they perceived to be associated with living near 7 different types of public facilities (i.e., nuclear reactor, oil refinery, airport, gas works, prison, district heating facility, and mental hospital). Two respondent groups lived .5 km and 1.4 km from a nuclear research reactor, 2 groups lived at similar distances from a district heating facility, and the control group lived about 10 km from both facilities. Statistically significant differences were found with respect to the item "nuclear reactor," with the group living 1.4 km from the reactor perceiving it to be riskier than the nearer group and the controls, suggesting that frequent contact with potentially threatening objects reduces the perceived hazard. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual and tactual perception of shape by young children.

Gave 3-4 yr olds a series of 2-choice matching problems involving visual and/or tactual perception. Contrary to S. A. Rose et al (1972) some shape discriminations were more difficult tactually than visually. Predicted differences between dissimilar and similar discrimination were not obtained. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual perception of sequential numerosity by normals and retardates.

Presented sequences of 2-10 50-msec light flashes at interstimulus intervals (ISIs) of 100, 200, 300, 400, 500, and 600 msec. for multiple- and single-locus conditions to 20 educable retardates and 20 equal MA normals. Numerosity discrimination of the younger, normal children was more accurate at all ISIs (p     

The necessity of a perception–action approach to definite distance perception: Monocular distance perception to guide reaching.

In this investigation of monocular perception of egocentric distance, the authors advocate the necessity of a perception–action approach because calibration is intrinsic to definite distance perception. A helmet-mounted camera and display were used to isolate optic flow generated by participants' head movements toward a target, and participants' reaches to place a stylus either in a target hole (Experiments 1, 2, and 4) or aligned under a target surface (Experiment 3) were analyzed. Conclusions are that binocular distance perception is accurate, monocular distance perception yields compression that is not eliminated by feedback, but feedback is used to eliminate underestimation generated by restriction of the size of the visual field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual perception. Knowing is seeing

New visual illusions provide further evidence for the influence of higher-order analyses of the visual scene on the perceived brightnesses of surfaces within that scene.     

Motion parallax and children's distance perception.

Studied the effectiveness of motion parallax for relative and absolute distance judgments using 48 2nd, 4th, and 6th graders and college adults. Two targets were viewed either monocularly with a fixed head, monocularly with head movements providing motion parallax, or binocularly with head movements providing motion parallax. Ss adjusted the distance of a comparison rod to match the perceived distance of the target, or simply indicated which was nearer. For absolute judgments, accuracy was not affected by age level of the Ss; however, a developmental decrease in the variability of judgment was observed. There were no grade effects for relative judgments. For both judgments, the addition of motion parallax information increased accuracy. Results indicate that children are capable of registering array velocity information for distance. The ability to register self-movement or to integrate self-movement and array motion in the perception of absolute distance may account for the observed developmental changes. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of two indicators of perceived egocentric distance under full-cue and reduced-cue conditions.

It has not been established that walking without vision to previewed targets is indeed controlled by perceived distance. To this end, we compared walking and verbal report as distance indicators, looking for a tight covariation in responses that would indicate control by a common variable. Targets from 79–500 cm away were presented under dark and well-lit conditions. Both verbal reports and walking indicated overestimation of near targets and underestimation of far targets under dark viewing conditions. Moreover, the finding that verbally reported distance plotted essentially as a single-valued function of walked distance and vice versa is evidence that both indicators were responding to the same internal variable, ostensibly perceived distance. In addition, binocular parallax, absolute motion parallax, and angular elevation were evaluated as distance cues, and only angular elevation exerted a large influence on perceived distance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual perception of numerosity in infancy.

Numerosity was defined as an invariant property of a collection of objects specifying its numerical size. Infants looked at displays of small numerosities that changed optic structure such that size was not tied to certain static or dynamic configurational properties of the display but remained constant across patterns of optic motion. The displayed figures moved continuously and at a constant speed. The trajectories were irregular and could produce occlusion of objects. The task used involved infant-controlled habituation of visual looking time. At ages 5 mo, 8 mo, and 13 mo, 44 infants were tested for the numerosities 2, 3, and 4 in 3 randomly ordered sessions. The results demonstrated that infants from the age of at least 5 mo perceive small numerosities. It appears that discrimination of units, rather than discrimination of characteristic patterns, underlies numerosity perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distortions in definite distance and shape perception as measured by reaching without and with haptic feedback.

Psychophysical studies reveal distortions in perception of distance and shape. Are reaches calibrated to eliminate distortions? Participants reached to the front, side, or back of a target sphere. In Experiment 1, feedforward reaches yielded distortions and outward drift. In Experiment 2, haptic feedback corrected distortions and instability. In Experiment 3, feedforward reaches with only haptic experience of targets replicated the shape distortions but drifted inward. This showed that outward drift in Experiment 1 was visually driven. In Experiment 4, visually guided reaches were accurate when participants used binocular vision but when they used monocular vision, reaches were distorted. Haptic feedback corrected inaccuracy and instability of distance but did not correct monocular shape distortions. Dynamic binocular vision is representative and accurate and merits further study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Haptic perception of the distance walked when blindfolded.

The ability to detect the distance walked when blindfolded using only haptic information generated by the walking activity was investigated. Participants walked a straight path until told to stop, turned, and attempted to return to their starting point. The path was completely featureless. Counting was prevented. Blindfolded, sighted participants traveled with a long cane or a trained sighted guide. Gait was varied or distorted In all experiments the return distance was a linear function of the set distance, with some participants giving and some conditions resulting in remarkably sensitive performances. The magnitude of errors was a linear function of step length. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Height perception: A function of social distance.

Investigated the effects of (a) status-related ethnic membership, and (b) the prejudice of the O on height perception. Ss were 126 undergraduates who were shown slides of various objects and people in a counter-balanced fashion. It was found that height-equated individuals rated high on the Bogardus Social Distance Scale were perceived as taller than height-equated individuals rated low on the Bogardus Social Distance Scale. The implications of these findings are discussed. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual space perception and visually directed action.

The results of 2 types of experiments are reported. In 1 type, Ss matched depth intervals on the ground plane that appeared equal to frontal intervals at the same distance. The depth intervals had to be made considerably larger than the frontal intervals to appear equal in length, with this physical inequality of equal-appearing intervals increasing with egocentric distance of the intervals (4–22 min). In the other type of experiment, Ss viewed targets lying on the ground plane and then, with eyes closed, attempted either to walk directly to their locations or to point continuously toward them while walking along paths that passed off to the side. Performance was quite accurate in both motoric tasks, indicating that the distortion in the mapping from physical to visual space evident in the visual matching task does not manifest itself in the visually open-loop motoric task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual perception of word chunks and beginning reading.

Asked 81 1st graders and 45 2nd graders to identify digraphs and trigraphs of high-frequency occurrence embedded in strings of 5 or 7 letters. Ss responded more frequently and more accurately to target items located at the beginning and end of the letter strings. Although success was unrelated to the frequency of occurrence of digraphs or trigraphs, the performance of 2nd graders was superior to that of 1st graders. Results suggest that since experience or instruction in reading does have an effect, frequency of occurrence in text may be an inadequate measure of the frequency with which students are exposed to the graphemic units studied. Skill in identifying word chunks was significantly related to measures of other elementary reading subskills and teacher ratings of oral reading proficiency. (French summary) (18 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contribution of listeners' approaching motion to auditory distance perception.

Of the several sources of acoustic information for distance perception, those arising from motion of the listener or sound source have received little attention. This motion-related information (recently called acoustic tau) is described, and experiments evaluating its utilization are presented. Accuracy and consistency at walking to the locations of briefly presented sounds were better when people listened while walking than while standing still. Manipulations of the sound to simulate shorter or longer target distances produced appropriate undershooting but not overshooting. The results indicate that people use motion-related acoustic information about distance to guide their locomotor actions, although they do not take full advantage of this information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)