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Results for “Distance Perception”

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At least 307 records · Page 17Linked to original sources
PubMed1989

Length distortion of temporally extended visual displays: similarity to haptic spatial perception.

Three experiments were designed to investigate length distortion--the tendency to inflate estimates of the inferred distance between two points, as the length of a circuitous pathway between them increases. This phenomenon, previously demonstrated with haptic and locomotor exploration (Lederman, Klatzky, Collins, & Wardell, 1987), was extended to vision through the presentation of pathways as a temporal sequence of illuminated points. The magnitude of the visual effect was less than that previously found in haptics, and conditions promoting the effect included a relatively slow presentation rate and moderately complex pathways. Commonalities in the pattern, if not the magnitude, of length distortion in vision and haptics suggest that similar processes of spatial encoding may underlie the phenomenon in both domains.

Adult↗
PubMed1981

Assimilation and contrast in the parallel lines illusion?

Judgments of 40 undergraduates indicated that the assimilative character of the parallel lines illusion was destroyed at large values of both context line length and separation of context and center line variables. Accommodation of a portion of these results requires a modification of Brigner's (1977) theory of perception of illusory extent.

Discrimination Learning↗
PubMedDate not supplied

Some effects of prestimulus activity and length of prestimulus observation on judgments of newborns' responses to sounds.

Previous work on the effects of prestimulus state on newborn auditory response is briefly reviewed. Subjectively assessed responses of nine newborns by five observers were studied as a function of (1) prestimulus activity level and (2) duration of prestimulus observation period. Response assessment was significantly affected for the former but not by the latter. For sounds which elicited a high proportion of responses, the prestimulus activity level had relatively little effect on judgment of response, whereas for sounds (and no-sound "control" trials) to which few responses were ascribed, prestimulus activity tended to be associated with positive ratings of response.

Acoustic Stimulation↗
PubMed1996

Is judging time-to-contact based on 'tau'?

An investigation was undertaken into whether judgments of time-to-contact between a laterally moving object and a bar are based on the direct perception of an optical variable (tau), or on the ratio between the perceived distance and perceived velocity of the object. A moving background was used to induce changes in the perceived velocities without changing the optical variables that specify time-to-contact. Background motion induced large systematic errors in the estimated time-to-contact. It is concluded that the judgment of time-to-contact is primarily based on the ratio between the perceived distance and the perceived velocity, and not on tau.

Acceleration↗
PubMed1988

Perception of the length of voluntary movements.

Two experiments were performed to study the ability of blindfolded subjects to estimate distance on the basis of proprioceptive cues. In the first experiment, subjects judged the length of metal rods that they were allowed to explore freely. With this access to positional as well as other cues, subjects' estimates were a nearly linear function of actual length. These data closely paralleled control measurements obtained under conditions of visual, rather than haptic, inspection. In the second experiment, each subject slid his or her index finger laterally along a straight path delimited by the apparatus, and then gave a magnitude estimate of the distance through which the finger had moved. Velocity of movement was manipulated by asking subjects, on each trial, to move at one of five speeds ranging from "very slow" to "very fast"; these instructions elicited velocities spanning a 100-to-1 range. Magnitude estimates of distance in this second experiment increased as a function of actual distance, but decreased as a function of velocity. This latter phenomenon resembles the dependence of perceived distance on velocity that has been shown by other investigators to occur when a stimulus object is drawn across the skin. The data of the present study are consistent with the hypothesis that the perceived length of an active movement depends on a combination of movement and position signals from primary and secondary sensory fibers in muscle spindles.

Adult↗
PubMed1995

Does perceived size depend on perceived distance? An argument from extended haptic perception.

Two experiments were directed at the comparison between two perspectives on the perception of size achieved by probing the gap between two occluded distal surfaces by means of a hand-held rod. One perspective was the classical size-distance invariance hypothesis developed for the problem of visual size perception with a central role for perceived distance; the other was the hypothesis that the extended haptic perception of gap size is specific to a physical invariant lambda of the dynamics of probing. Experiment 1 examined the relation between hepatically perceived gap size and haptically perceived gap distance. No causal connection between the two was found, and all the variance in perceived size was accounted for by lambda. Experiment 2 manipulated the rotational inertia of the probe. Its effect was different for the two perceptions of size and distance, underscoring their independence. The indifference of perceived size to perceived distance was discussed in reference to identifying invariants for both the haptic and the visual perception of size at a distance.

Adult↗
PubMed1989

The roles of convergence and apparent distance in depth constancy with motion parallax.

The question of whether motion parallax is calibrated by convergence or by apparent distance for depth perception was addressed in three experiments. In Experiment 1, a random dot parallactic display was viewed monocularly at a distance of 80 cm, and the convergence angles were set for distances of 40, 60, and 80 cm. Averaged apparent depth was not different across conditions. In Experiment 2, a display consisting of one surface showing dollar bills and one surface showing random dots was viewed monocularly at a distance of 80 cm. It was presented at two different apparent distances, which were manipulated by varying the size of the dollar bills. In one condition, normally sized dollar bills were presented, and in another condition, the size was reduced by 30%. The averaged apparent depth associated with the small-bill display was larger than the depth associated with the normally sized bill display. In Experiment 3, a random dot display was viewed monocularly at 120 cm. In the primary condition, the random dot display was viewed with an induction screen at 80 cm, and it was moved from side to side such that it appeared stationary and close to the plane of the induction screen. In a comparison condition, the display was viewed without the induction screen and was moving from side to side at 120 cm. In another comparison condition, the display was again viewed without the induction screen but was stationary at 120 cm. Observers adjusted the extent of motion parallax so that apparent depth was 1 cm. The mean extent of parallax was larger in the primary conditio.(ABSTRACT TRUNCATED AT 250 WORDS)

Accommodation, Ocular↗
PubMed1991

Transformation theory of size judgment.

Perception of size is assessed by having observers adjust a comparison target at a fixed distance to match the size of a standard located at different distances. Results depend on instructions, target orientation, and available stimulus cues. A mathematical theory assumes that the brain performs an inverse transformation on the proximal information impinging on the retina to recover the original distal size of the target. Results depend on the target visual angle, and the effective target distance and orientation applied in performing the inverse transformation. Effective values are linked to instructions, target location, and stimulus cues. Two models are developed and successfully fit to empirical data. One emphasizes the distance parameter; the second, the orientation parameter.

Attention↗
PubMed1990

The relationship between visual persistence and event perception in bistable motion display.

Observers viewed two alternating frames, each consisting of three rectangular bars displaced laterally by one cycle in one frame with respect to the other. At long interframe intervals (IFIs) observers perceived a group of three bars moving as a whole (group motion), and at short IFIs the overlapping elements in the two frames appeared stationary, while the third element appeared to move from one end of the display to the other (element motion). The upper temporal limit for perceiving element motion was reduced when bars with blurred edges were used and when either frame duration or bar size was increased. However, when inner and outer elements had different sizes, the element motion percept was dominant up to 230 ms IFI. These findings may be interpreted in terms of spatial tuning of motion mechanisms involved in the perception of bistable apparent motion.

Attention↗
PubMed1994

Spatial scale dependent in-phase and anti-phase directional biases in the perception of self-organized motion patterns.

A long row of evenly spaced dots is displaced on successive frames by half the distance between the dots. Although these stimuli are directionally ambiguous, spatially and temporally coherent unidirectional and oscillatory motion patterns are perceived as a result of the temporal persistence of competing in-phase and anti-phase directional biases, respectively. The perceiver's spatial scale is critical is determining whether dots are near enough to favor an in-phase bias or far enough apart to favor an anti-phase bias. The results are explained by a differential-gradient model of cooperative interaction, which specifies that the strength of facilitating (excitatory) interactions among motion detectors with similar directional selectivity falls off with distance at a greater rate than the strength of competing inhibiting interactions.

Distance Perception↗