[Time perception in an extreme situation].
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The effects of methylphenidate (MPH) on performance of a time-production task were studied in 17 children with attention-deficit/hyperactivity disorder who participated in 1 test session on and 1 off MPH. Participants held a response lever down for at least 10 but no longer than 14 s. Administration of MPH had no effect on the number of correct responses or on the mean duration of lever holds. MPH administration significantly decreased timing response variability, increased holds of 10- to 11-s duration, and decreased lever holds of extremely short durations. These results indicate that administration of MPH resulted in more precise timing performance without changing the mean duration of lever holds, suggesting an enhancement in working memory.
Two groups of 5- to 6-yr.-old children estimated the time required to view 15 color slides containing an assortment of familiar objects. In one group, the pictures appeared in categorical order. A second group viewed the same 15 slides in a random order. The results showed that, although picture-recall was similar for the two groups, children in the category group estimated significantly longer durations than subjects in the random condition. The findings were discussed in the context of Ornstein's 1969 storage size hypothesis.
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STUDY OBJECTIVE: To assess the ability of patients to accurately estimate specific waiting times in the emergency department. METHODS: A questionnaire was administered by telephone to a random sample of 776 patients (or parents or responsible caretakers, if appropriate) who had been treated within the previous 2 to 4 weeks in the ED of a suburban hospital. Respondents were asked their perceptions of two particular time frames: (1) the time elapsed from triage until initial examination by the emergency physician (physician waiting time [PWT]), and (2) the time elapsed from triage until departure from the ED (total waiting time [TWT]). Corresponding actual times were extracted from a computerized database. Time frames were divided into discrete periods for comparison. The correspondence between actual and perceived times was assessed by optimal data analysis. RESULTS: Only 22.3% of the respondents accurately estimated PWT. Although this level of accuracy is statistically significant (P < .0001), it reflects only 11% of the theoretically possible improvement in accuracy beyond chance. More respondents overestimated than underestimated PWT (49.9% versus 27.8%, respectively). In contrast, TWT was accurately estimated by 36.6% of the respondents (P < .0001), reflecting 18% of the theoretically possible improvement in accuracy beyond chance. Fewer respondents overestimated than underestimated TWT (24.5% versus 38.9%, respectively). CONCLUSION: Patients are not very accurate in their estimation of actual waiting times. Although fewer than one fourth of the respondents overestimated the TWT spent in the ED, almost half the respondents overestimated the PWT.
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The present experiment assessed intersensory differences in temporal judgments, that is, auditory stimuli are perceived as longer than physically equivalent visual stimuli. The results confirmed the intersensory difference. Auditorially defined intervals were experienced as longer than visually defined intervals. Auditory boundaries were perceived as longer than visual ones. An interaction of boundary modality and interval modality was obtained which suggested that auditorially defined intervals provided more temporal information about events occurring in close temporal proximity than visually defined intervals. It was hypothesized that cognitive factors, specifically stimulus complexity, would affect the auditory and visual systems differentially. This hypothesis was not substantiated, although highly complex stimuli were experienced as longer than those of low complexity.
This experiment investigated the effect of a signal (i.e., a click) warning of the arrival of a stimulus to be timed on temporal discrimination in children aged 3, 5, and 8 years (N=86), using a bisection task with visual stimuli ranging from 0.5 to 2s or 1 to 4s. In all groups, the psychophysical functions were orderly with the proportion of long responses increasing with the stimulus duration, although the steepness of functions increased with age. Stimulus durations were judged to be longer with than without the click in all age groups. With the click, time sensitivity also improved and more particularly in the younger children. The statistical results suggest, within the framework of the scalar timing theory, that the click reduces the closing latency of the switch that connects the pacemaker to the accumulator in the internal clock and also reduces its trial-by-trial variability.
Subjects estimated the duration of five different time intervals, either filled or unfilled, in relation to one or two standard intervals. Half of the subjects were presented with the standard at the beginning of the experiment only, and half were presented with the standard before every interval. The five estimations were then used to calculate, for each subject, the exponent in Stevens' Power Law which describes the form of the power relationship. The resulting over-all exponent of .91, although nearly linear, was significantly different from 1.0. The data were then analyzed by a 2 X 2 X 2 analysis of variance which showed a significant interaction between presenting the standard either once or before each interval with the duration of the standard.
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The present research joins previous efforts to define more clearly the phenomenon of perceived time as an important social-psychological dimension. In this study, time was considered a socially existential variable that can most meaningfully be measured by comparing two or more subjectively experienced durations, each with the other(s). Combining this view of time judgment with the adaptation level/optimal arousal principle, two hypotheses were tested: (a) that test stimuli differing in degree of complexity elicit from the individual differential degrees of affect, and (b) that intervals during which the individual is exposed to either overly simple or overly complex stimuli are judged as comparatively longer than objectively equal durations filled with moderately complex stimuli. Both hypotheses were affirmed.
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