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At least 145 records · Page 8Linked to original sources
PubMed1981

The effect of search time on perception.

A group of 100 carefully selected chest radiographs was read by ten observers, five experienced and five inexperienced. The radiographs were chosen to present the readers with a disproportionately large number of both subtle abnormalities and nonpulmonary lesions. Each reader was allowed to search the radiographs for as long as appropriate, up to a maximum of four minutes. The length of time taken for each observation was recorded to the nearest second. The time-perception data were plotted on both linear and semilogarithmic graphs. The results showed that experienced readers concluded their visual search while positive detection rate was higher than the rate for false-positives. For lesions in the central phasic, with both a rapid and a slow component of perception. If these data are plotted on a semilogarithmic scale, each of the two components plots as a straight line. For lesions in the periphery of the radiograph (chest wall and upper abdomen), the time-perception curve is monophasic, showing only a slow component.

False Negative Reactions↗
PubMed1995

Localization of a cerebellar timing process using PET.

We used positron emission tomography (PET) to localize a cerebellar timing function. Six healthy volunteers estimated time differences by comparing a test interval (defined by two tones) with a standard interval. In the timing condition, subjects lifted their right index finger if the test interval was shorter and their right middle finger if it was longer than the standard interval. In the control condition, the two intervals were identical and subjects had to alternate between lifting their index and middle fingers. We examined regional cerebral blood flow (rCBF) using the standard C15O2 inhalation technique. Comparison of control and rest conditions revealed significant increases of rCBF during the control condition in the inferior parts of the ipsilateral cerebellar hemisphere, reflecting finger movements. Comparison of timing and control conditions showed additional activations of the cerebellar vermis and hemispheres bilaterally during the timing condition, reflecting the cerebellar timing process. We conclude that the cerebellum is involved in time-critical perception ("timing"). This nonmotor task can be separated from a motor task (finger movement).

Acoustic Stimulation↗
PubMed1980

Cerebral asymmetry in the perceived duration of color stimuli.

20 right-handed males judged the duration of small and large colored circles, which were briefly exposed in the left, center, and right visual fields. Perceived duration was a logarithmic function of exposure duration and a positive function of size and chromaticity. Over-all accuracy was equivalent in the left and right visual fields, but the effects of chromaticity and duration on subjects' judgments were asymmetrical. These and other findings suggest a two-process model of time perception in which there is right hemispheric control over a visual information processor and left hemispheric control over a timer.

Color Perception↗
PubMed1981

Growth of apparent duration: effect of melodic and non-melodic tonal variation.

Time estimates of 12 intervals of 15 to 65 sec. duration were obtained from 30 subjects by one of two methods, magnitude estimation and cross-modal matching. Three kinds of sequences of musical notes were presented during stimulus intervals; repetitive, melodic, and random. Within all sequences, notes were of equal duration and with equal pauses between them. In all cases, the relationship between perceived and physical time is consistent with Stevens' power law. Exponents derived from both kinds of estimates were significantly affected by the content of the interval. Exponents derived for repetitive sequences were not different from 1 and were significantly larger than exponents derived from random or melodic sequences. These results are inconsistent with the view that the predictability, familiarity, or codability of event occurring in the stimulus interval is inversely related to the perceived duration of that interval. There is some indication that the effect of the content of the interval on judgments of duration varies with the magnitude of the duration being judged. Perhaps the relationship holds only within certain parameters and, when these are exceeded, other factors mask the effect. A two-process theory of time perception, one which considers these other factors and explains the present results, is proposed.

Humans↗
PubMed1983

The filled-duration illusion: limits of duration of interval and auditory fillers.

Two experiments were conducted to explore parameters of the filled-duration illusion, i.e., intervals filled with stimuli are perceived as longer than empty intervals of equal physical duration. It was hypothesized that the illusion would be found only for intervals of short duration, i.e., a few seconds, and that filled intervals would vary in perceived duration as a function of the type of "filler." Auditory tones were used as boundary and filler stimuli in a counterbalanced (Exp. I) and randomized (Exp. II) design that covered 9 intervals ranging from 1 to 60 sec. A psychophysical method of verbal estimation with single stimuli was employed. The first hypothesis was supported in that only with the short intervals (1 and 3 sec.) was there any evidence of a filled-duration illusion. The type of filler stimulus was important only in the 1-sec. intervals. Results are interpreted in terms of information-processing models for time perception.

Adolescent↗
PubMed1978

Effect of density and environmental noise on perception of time, the situation, oneself and others.

The effects of density, intrusion of one's personal space, sex of subject, group composition, and environmental noise on the perception of time, the situation, oneself and others were investigated in this study. Generally, the results indicated that (1) both density and the intrusion of personal space concurrently affect the perception of crowding, (2) the physical factors interacted with the social and personal factors to affect the perception of several aspects of the situation, and (3) the environmental noise did not, for the most part, affect the perception of the situation.

Crowding↗
PubMed1976

Facilitation of stereopsis from a large disparity random-dot stereogram by various monocular features: further findings (a short note).

This experiment examined the effects of adding five different kinds of prominent monocular features to a large-disparity random-dot stereogram. It was found that features which enclosed the disparate area produced the shortest initial perception times for fusion. The longer initial perception times for stimuli containing features without this enclosing property are explained in terms of less-helpful guidance of saccadic eye movements prior to the establishment of fusion. Subsequent reductions in perception times for these latter stimuli could be due to perceptual learning within the eye movement control system.

Depth Perception↗
PubMed1988

Ratio judgments of empty durations with numeric scales.

A study is reported on the perception of empty time intervals marked by auditory signals. Nakajima's supplement hypothesis, which states that the subjective duration of a subjectively empty time interval is proportional to its physical duration plus a constant of approximately 80 ms, was examined quantitatively. Although this hypothesis has been used to explain various general aspects of time perception, from a global viewpoint, it has lacked the quantitative data necessary to describe the shape of the psychophysical functions mathematically. In the present study, subjects used two positive numbers to estimate the subjective ratio (m:n) between the durations of two serial or separate empty intervals. The psychophysical functions for empty durations 50-600 ms long could be approximated by a straight line with a positive gamma-intercept, as predicted by the hypothesis. The effective range of the hypothesis could be extended to approximately 1200 ms. A power function (without any modifications) also gave good approximations. The reliability and validity of the supplement hypothesis are discussed.

Adult↗
PubMed1992

Effects of atropine on operant test battery performance in rhesus monkeys.

The acute behavioral effects of atropine sulfate were assessed using a battery of complex food-reinforced operant tasks that included: temporal response differentiation (TRD, n = 7); delayed matching-to-sample (DMTS, n = 6), progressive ratio (PR, n = 8), incremental repeated acquisition (IRA, n = 8), and conditioned position responding (CPR, n = 8). Performance in these tasks is thought to depend primarily upon specific brain functions such as time perception, short-term memory and attention, motivation, learning, and color and position discrimination, respectively. Atropine sulfate (0.01-0.56 mg/kg iv), given 15-min pretesting, produced significant dose-dependent decreases in the number of reinforcers obtained in all tasks. Response rates decreased significantly at greater than or equal to 0.03 mg/kg for the learning and discrimination tasks, at greater than or equal to 0.10 mg/kg for the motivation and short-term memory and attention tasks, and at greater than or equal to 0.30 mg/kg for the time perception task. Response accuracies were significantly decreased at doses greater than or equal to 0.10 mg/kg for the learning, discrimination, and short-term memory and attention tasks, and at greater than or equal to 0.30 mg/kg for the time perception task. Thus, the order of task sensitivity to any disruption by atropine is learning = color and position discrimination greater than time perception = short-term memory and attention = motivation (IRA = CPR greater than TRD = DMTS = PR). Thus in monkeys, the rates of responding in operant tasks designed to model learning and color and position discrimination were the most sensitive measures to atropine's behavioral effects. Accuracy in these same task was also disrupted but at higher doses. These data support the hypothesis that cholinergic systems play a greater role in the speed (but not accuracy) of performance of our learning and discrimination tasks compared to all other tasks. Accuracy of responding in these and the short-term memory task, all of which involve the use of lights as visual stimuli, was more sensitive to disruption by atropine than those tasks which did not utilize such strong visual stimuli.

Animals↗
PubMed1991

Influence of age, gender, height and education on vibration sense. A study by tuning fork in 192 normal subjects.

We measured perception time of the vibratory stimulus from a 128 cps tuning fork in 96 male and 96 female normal subjects equally subdivided into 8 age decades. The following sites were examined: clavicula, olecranon, styloid apophysis of ulna and radius, anterosuperior spina of ilium, rotula (patella), internal and external malleolus. Reproducibility between different examiners and between tests by the same examiner on different days was good. There was a marked regional variation with longer perception times at the distal regions of upper limbs. A non linear age-related decrease in vibration sense was found in all regions. Males had longer perception times at clavicula, females at distal limbs; the latter finding might be explained by shorter stature in females. Perception times at distal limbs were longer in subjects with higher education levels. The study provides normative data for vibration sense in different regions and defines the effects on it of age, gender, height and education.

Adolescent↗
PubMed1988

[The function of the counting of time as the basis for the individual adaptive activity of the nervous system].

An important role of time factor in adaptive process of organisms is shown on the basis of great literary material. The time perception is a result of the interrelationship of the so-called "biological clock" and learning during the whole ontogenesis. The hypothetical mechanisms of time perception are discussed. In own experiments the authors revealed more distinct expressiveness of high-frequency components in electroencephalogram spectrum and less expressiveness of low-frequency components in subjects underestimating time intervals compared with subjects overestimating them. A conception on the role of individual characteristics of nervous system in time perception is developed.

Adaptation, Physiological↗
PubMed1992

The perception of time as a factor in Rogers' Science of Unitary Human Beings: a literature review.

This literature review examines an operationalization of Martha Rogers' Science of Unitary Human Beings. The principle of helicy and the theory of accelerating evolution has been used by a number of authors as a theoretical framework for the exploration of how patients, particularly those who are elderly, perceive the passage of time. Although there is no conclusive evidence to support the aspect of Rogers' theory of accelerating evolution that suggests that as people grow older they perceive time as passing more quickly, there is evidence that suggests that different elderly patients can have a variable perception of the passage of time. For example, some patients perceive the passage of time as rapid and will be happy to sit quietly. Others may perceive the passage of time as occurring more slowly and will require diversional therapy. A conclusion is reached that nurses should include individual assessments of the patients' perception of the passage of time in order to identify accurately the degree of need for diversional activities.

Aged↗