PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Distance Perception”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources
PubMed1991

Induced motion: isolation and dissociation of egocentric and vection-entrained components.

Induced motion (IM) is illusory motion of a stationary test target opposite to the direction of the real motion of the inducing stimulus. We define egocentric IM as an apparent motion of the test target relative to the observer, and vection-entrained IM as an apparent motion of a stationary object along with an apparent motion of the self (vection) induced by the same stimulus. These two forms of IM are often confounded, and tests for distinguishing between them have not been devised. We have devised such tests. Our test for egocentric IM relies on evidence that this form of IM is due mainly to a misregistration of eye movements when optokinetic nystagmus (OKN) is inhibited, and on evidence that OKN is evoked only by stimuli in the plane of convergence. Our test for vection-entrained IM relies on evidence that vection is evoked only by the more distant of two superimposed inducing stimuli. Thus we found egocentric IM to be induced without vection or vection-entrained IM when subjects converged on a foreground moving display with a stationary display in the background, and vection-entrained IM to be induced without egocentric IM when subjects converged on a stationary-foreground display with a moving display in the background. The two types of IM were evoked in opposite directions at the same time when subjects converged on a foreground moving display while a background display moved in the opposite direction. The two forms of IM showed no signs of interaction, and we conclude that they rely on independent motion mechanisms that operate within distinct frames of reference. A control experiment suggested that the depth adjacency effect in IM is determined by the depth adjacency of the inducing stimulus to convergence, not just to the test target.

Acceleration↗
PubMed1996

The depiction of distance: a Bartelian analysis.

Work by Bartel has shown that observers make systematic errors when attempting to set a receding row of staves at equal intervals, and make even-more-pronounced errors in the same direction when drawing a similar row; consequently, the factors that contribute to this systematic distortion in spatial representation were examined. The results indicate that the tendency to overestimate nearer distances and underestimate further distances in pictorial space may be enhanced both by increasing the size ratio of the nearest and furthest pictorial elements and by increasing the angle of convergence of represented parallel contours. However, it is clear that size ratio is the more powerful independent variable. The reasons for this discrepancy are discussed and an explanation of the pattern of pictorial distortion, in terms of a compromise between an objective representation of the relative estimated distance of the depicted distances and an inaccurately anticipated optical projection, is proffered.

Depth Perception↗
PubMed2006

Visual memory for moving scenes.

In the present study, memory for picture boundaries was measured with scenes that simulated self-motion along the depth axis. The results indicated that boundary extension (a distortion in memory for picture boundaries) occurred with moving scenes in the same manner as that reported previously for static scenes. Furthermore, motion affected memory for the boundaries but this effect of motion was not consistent with representational momentum of the self (memory being further forward in a motion trajectory than actually shown). We also found that memory for the final position of the depicted self in a moving scene was influenced by properties of the optical expansion pattern. The results are consistent with a conceptual framework in which the mechanisms that underlie boundary extension and representational momentum (a) process different information and (b) both contribute to the integration of successive views of a scene while the scene is changing.

Color Perception↗
PubMed1978

An intra-cultural investigation of susceptibility to 'perspective' and 'non-perspective' spatial illusions.

Conventional Müller-Lyer and modified Müller-Lyer (without 'perspective' cues) illusions were presented to two samples of children aged between eight and 19, matched in education, but living in 'carpentered' and 'uncarpentered' environments in Zambia. Traditional differences in susceptibility have been obtained with both the variations of the Müller-Lyer illusion. In view of the lack of perspective cues in one of these, it is concluded that the perspective theory as presented within the 'carpentered world hypothesis' is inadequate. Since these differences are intra-cultural, they also do not support the hypothesis which suggests that cross-cultural variations in illusion susceptibility are due to genetic factors--such as macular (or retinal) pigmentation.

Adolescent↗
PubMed1975

Effects of training on dynamic stereo acuity performancy by males and females.

Dynamic stereo acuity thresholds were obtained for 30 male and female Ss at speeds of rotation of 120 degrees/sec. after pretraining at either O degree, 60 degrees, or 120 degrees/sec. Under conditions of no pretraining females showed significantly larger discrimination errors than males. Pretraining, however, resulted in comparable threshold performance between males and females. Socio-cultural factors responsible for these differences are suggested.

Depth Perception↗
PubMed1981

Information for the spatial factor in Korte's 3rd Law of apparent motion.

The experiments reported here show that Korte's space-time invariance equation governing perception of apparent motion is limited to situations in which metric or apparent separation of targets define but a single interval of space. Variation in interstimulus intervals and metric separation of targets did not influence the perception of apparent motion when the background array was structured to depict apparently equal intervals of space. These results provide a test of Koffka's and more recently Gibson's view that higher order properties of intervals of space specify the spatial factor in apparent movement.

Adult↗
PubMed1994

Apparent depth threshold for the Benussi effect.

Using the single staircase psychophysical method, the apparent depth threshold for the Benussi effect was determined for 5 observers. The threshold occurred at an eccentricity of 2r/3, where r equals the radius of the larger circle expressed in millimeters.

Depth Perception↗
PubMed2006

Location matters: why target location impacts performance in orientation tasks.

This research explores human performance in a spatial orientation task. In three experiments, participants saw a target highlighted in a visual scene and were asked to locate it on a map of the space. Across all of the experiments, the target's location in the visual scene influenced the participants' response times. Generally, response times increased when the target was located farther away from the viewer, when the target was farther to one side or the other, and when more distractors were nearby. However, there were important exceptions to these findings, suggesting that participants encode the location of a target hierarchically, using different features of the space depending on the target's particular location. We conclude that participants perform such tasks by extracting a description from the egocentric view and then transforming that description to allow them to find the target on the map.

Adult↗
PubMed1991

Effect of feature similarity on illusory conjunctions.

In four experiments, we examined whether the phenomenon of illusory conjunctions is constrained by feature similarity. Specifically, are illusory conjunctions more likely to occur between items with similar features than between items with dissimilar features? Feature similarity was manipulated in two dimensions: color and shape. Experiment 1 demonstrated that more illusory conjunctions occur between items with similar colors than between items with dissimilar colors. A similar effect was found for letter similarity in Experiment 2. Experiments 3 and 4 demonstrated that the similarity effect is still obtained for illusory conjunctions even when identification of the relevant features is near perfect. These findings introduce a new constraint in the process of feature integration. Additional implications of the similarity constraint for theories of feature integration are discussed.

Attention↗
PubMed1998

Visual inertia of rotating 3-D objects.

Five experiments were designed to determine whether a rotating, transparent 3-D cloud of dots (simulated sphere) could influence the perceived direction of rotation of a subsequent sphere. Experiment 1 established conditions under which the direction of rotation of a virtual sphere was perceived unambiguously. When a near-far luminance difference and perspective depth cues were present, observers consistently saw the sphere rotate in the intended direction. In Experiment 2, a near-far luminance difference was used to create an unambiguous rotation sequence that was followed by a directionally ambiguous rotation sequence that lacked both the near-far luminance cue and the perspective cue. Observers consistently saw the second sequence as rotating in the same direction as the first, indicating the presence of 3-D visual inertia. Experiment 3 showed that 3-D visual inertia was sufficiently powerful to bias the perceived direction of a rotation sequence made unambiguous by a near-far luminance cue. Experiment 5 showed that 3-D visual inertia could be obtained using an occlusion depth cue to create an unambiguous inertia-inducing sequence. Finally, Experiments 2, 4, and 5 all revealed a fast-decay phase of inertia that lasted for approximately 800 msec, followed by an asymptotic phase that lasted for periods as long as 1,600 msec. The implications of these findings are examined with respect to motion mechanisms of 3-D visual inertia.

Contrast Sensitivity↗