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Results for “Distance Perception”

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At least 1,261 records · Page 70Linked to original sources
PubMed1975

Effect of length, density, and angel between arms of Gestalt grouping.

In three experiments, subjects viewed two lines (arms) of dots in which one dot was shared by both arms, then judged with which arm the shared dot appeared to group. Length of an arm, density of the dots in the arm, and angle between arms were manipulated. Increasing the density of an arm increased grouping with that arm regardless of the angle between arms. Increasing the length of an arm however, increased grouping when arms met at 30 degree but not at 180 degree; intermediate angles produced intermediate effects. Advantage of the present method's simplification of the stimulus display are discussed.

Distance Perception↗
PubMed1981

Interference effects in recalling movements.

In two experiments, the interaction of location and distance cues in the recall of pre-selected movements was investigated. In Expt 1, separate groups of subjects were required to remember either ther terminal location of, or the distance moved during, a criterion movement pre-selected within a 30 cm response region. Following either a 5 s or 30 s unfilled retention interval, subjects were required to recall the criterion movement using the particular movement cue (i.e. location or distance) in question. In Expt 2, a similar procedure was used, except that recall of the criterion movement followed either a 5 s or a 20 s unfilled, or a 20 s filled (backward counting) retention interval. Systematic manipulation of both the direction and magnitude of the starting position for recall movements revealed the subjects were unable to make the movement uninfluenced by the "unattended' movement cue. The interfering effect of this irrelevant cue was independent of the ongoing activity during the retention interval. The results suggest that memory for preselected movements is based on a combination of the two movement cues generated during production of the criterion movement.

Cues↗
PubMed1982

The accuracy of eye-gaze judgment: a signal detection approach.

Two studies are reported which tested the hypothesis that eye-gaze discriminability declines with increased interpersonal distance and that this decline produces an overestimation bias. Signal detection theory was used to provide separate indices of discriminability and bias. Discriminability declined with both increased distance and, in one study, with decreased lighting. The tendency of the subject to guess that gaze was occurring when it was not mirrored the changes in discriminability, supporting the hypothesis.

Adult↗
PubMed1989

The construction and assessment of mental maps.

In investigations into the manner in which people store spatial information, experimental subjects are often asked to estimate the distances and bearings between various landmarks. Methodology is described for constructing the mental map underlying a subject's matrix of distances, and the mental map underlying a subject's matrix of bearings. Also presented are methods of comparing matrices of distances or bearings, and the mental maps constructed from them, with the geographical map; this enables an assessment of differences between them. Some statistical models of disorientation are considered, and a method of choosing between them is described.

Attention↗
PubMed1976

Reversal of the behavioural effects of monocular deprivation in the kitten.

1. Eighteen kittens were monocularly deprived of vision until the age of 5, 6 or 7 weeks. Their eyes were then reverse-sutured, and they were allowed to survive for 3-63 days, before physiological recording from area 17. 2. At the time the reverse-suture was performed, and immediately before the recording session, each kitten was tested separately in the two eyes to elicit five simple behavioural responses: optokinetic nystagmus, visual startle reaction, visually-guided paw placing, visual following and negotiation of a "visual cliff". 3. Following the opening of their initially deprived eye, all kittens appeared behaviourally blind when forced to use that eye; their performance through the initially open eye was then perfect on all tests. After the period of reversed lid-suture, however, their performance when using the initially deprived eye had improved, while that through the initially open eye deteriorated. This complementary improvement and deterioration was most rapid in kittens reverse-sutured at the age of 5 weeks, and less rapid when reverse-suturing was delayed until the age of 6 or 7 weeks. 4. Most of the kittens showed gross abnormalities of interocular alignment, and exhibited marked exotropia or esotropia. 5. The results of these tests were well correlated with the changes seen in cortical ocular dominance in the same animals.

Age Factors↗
PubMed2005

Invariance of evoked-potential echo-responses to target strength and distance in an echolocating false killer whale.

Brain auditory evoked potentials (AEPs) were recorded in a false killer whale Pseudorca crassidens trained to accept suction-cup EEG electrodes and to detect targets by echolocation. AEP collection was triggered by echolocation pulses transmitted by the animal. The target strength varied from -22 to -40 dB; the distance varied from 1.5 to 6 m. All the records contained two AEP sets: the first one of a constant latency (transmission-related AEP) and a second one with a delay proportional to the distance (echo-related AEP). The amplitude of echo-related AEPs was almost independent of both target strength and distance, though combined variation of these two parameters resulted in echo intensity variation within a range of 42 dB. The amplitude of transmission-related AEPs was independent of distance but dependent on target strength: the less the target strength, the higher the amplitude. Recording of transmitted pulses has not shown their intensity dependence on target strength. It is supposed that the constancy of echo-related AEP results from variation of hearing sensitivity depending on the target strength and release of echo-related responses from masking by transmitted pulses depending on the distance.

Animals↗
PubMed2002

Separate sources of spatial information for distance and location in rapid aiming movements.

The purpose of this research was to examine the role of distance and location information in the production of rapid aiming movements. Participants performed an aiming task consisting of horizontal left-handed elbow flexion movements that translated to movements of a cursor on an oscilloscope screen. The location of the home position and the target on the oscilloscope screen were fixed but the initial angle of the elbow was varied randomly. Participants were informed that the required distance was always constant. Initial impulse and error correction phases were analyzed to examine whether separate spatial codes for distance and position were used in the control of these two movement phases. The results indicated that initial impulse endpoints and the final positions of the limb overshot the target from the leftmost starting positions, while they undershot the target from the rightmost starting positions. Also, varying the initial angle of the elbow had a greater influence on the final position of the limb than initial impulse endpoints.

Biomechanical Phenomena↗
PubMed2006

The ant odometer: stepping on stilts and stumps.

Desert ants, Cataglyphis, navigate in their vast desert habitat by path integration. They continuously integrate directions steered (as determined by their celestial compass) and distances traveled, gauged by as-yet-unknown mechanisms. Here we test the hypothesis that navigating ants measure distances traveled by using some kind of step integrator, or "step counter." We manipulated the lengths of the legs and, hence, the stride lengths, in freely walking ants. Animals with elongated ("stilts") or shortened legs ("stumps") take larger or shorter strides, respectively, and concomitantly misgauge travel distance. Travel distance is overestimated by experimental animals walking on stilts and underestimated by animals walking on stumps.

Animals↗
PubMed1959

Magnitude of the moon illusion as a function of the age of the observer.

The diminution in the apparent size of an object when viewed overhead as compared with its apparent size in the horizontal plane is greater for children than for adults. This relationship, of which the well-known moon illusion is a special case, is interpreted to be a consequence of the normal development of size constancy.

Adult↗
PubMed1971

Infant responses to impending collision: optical and real.

Twenty-four infants ranging in age from 2 to 11 weeks responded to symmetrically expanding shadows, which optically specify an approaching object, with an integrated avoidance response and upset. This response did not occur for asymmetrically expanding shadows nor for contracting shadows that specify an object on a miss path and a receding object. The response was observed in all the infants regardless of age, and the addition of kinetic depth information to the displays did not increase the intensity or likelihood of the response. In a second experiment, seven infants defensively reacted to the approach of a real object except when it was on a miss path.

Avoidance Learning↗
PubMed1971

Echolocation in bats: signal processing of echoes for target range.

Echolocating bats Eptesicus fuscus and Phyllostomus hastatus can discriminate between the nearer and farther of two targets. Their errors in discrimination are predicted accurately by the autocorrelation functions of their sonar cries. These bats behave as though they have an ideal sonar system which cross correlates the transmitted cry with the returning echo to extract targetrange information.

Animals↗