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Time perception: effects of sex and sound intensity on scales of subjective duration.

Six women and six men reproduced ten time intervals varying in logarithmic steps between 1.3 and 20 s. The durations were indicated by white noise of 10, 25, 40 and 55 dB SL, different sound intensities in different sessions. It was found that (i) greater sound intensity entails shorter reproductions, and (ii) reproductions by male observers are shorter than those by female, although for both (i) and (ii) there is an interaction with the standard durations. The data were treated in accordance with the "parallel-clock model" (Eisler, 1975), whereby the parameters of the psychophysical power function are determined from duration reproduction data. As in previous experiments (Eisler, 1975), the data showed a break in the function entailing two segments. The effect of sound intensity could be attributed to the exponent, which was lower for stronger noise, and the effect of sex to the weight coefficient of the upper relative to the lower segment of the psychophysical function, the coefficient being lower for men.

Adult

Ethnic differences in time perception: a comparison of Anglo and Mexican Americans.

Social scientists have presented an image of the Mexican American as locked into the present, incapable, or unwilling to project plans and events into the future. This is seen as responsible in part for the lack of social mobility and assimilation exhibited by Mexican Americans. However, there is little empirical support for the contention that Mexican Americans have a restricted sense of future events. The present study compared the temporal perspectives of 31 Mexican American and 41 Anglo American college students. No marked differences were observed.

Adult

Time perception and hemodialysis.

Subtle alterations in neurological function are often difficult to identify and even harder to quantitate. The identification of a neurotoxic state existing before overt behavioral changes occur has eluded quantification. It was hypothesized that a challenging signal-detection procedure would be used to assess neurological function of dialysis patients and other subjects, the degree of uremic toxicity occuring during an interdialytic interval, and the effects of neuroactive drugs. A vigilance task demanding the detection of an irregularly flashing light from a matrix of regularly flashing lights was administered to 3 groups of 15 men: patients undergoing maintenance hemodialysis, patients with chronic illness and no kidney disease, and healthy subjects. The procedure was found to yield a reliable measure; average test-retest correlation was 0.93, which differentiated not only within the hemodialysis cycle (p less than 0.001), between groups (p less than 0.001), but was also related to the recency of neuroactive drugs ingested (p less than 0.01).

Arthritis

Voice onset time perception in Japanese aphasic patients.

This study examines identification of the synthetic speech stimuli [ga] and [ka] of varying voice onset times (VOTs) in 17 Japanese aphasic subjects. Approximately two-thirds of the aphasic subjects showed deterioration in performance of VOT identification of the stimuli. A quantitative analysis of the results indicates that the problems of the majority of these subjects may be attributable not only to difficulty in labeling the stimuli but also to difficulty in processing the acoustic and/or phonetic information of the stimuli.

Adult

[Effect of observation time on the perception of details in x-ray pictures].

The authors studied the influence of perception time on the quantified image quality of radiographs, using as an experimental basis the target presentation time during which there was no active involvement of the observer. No change in the influence on the observer was seen down to an observation time of 1 sec.; there was a slight but practically negligible drop on further reduction to 0.5 sec. At 0.1 sec. there was a drop that would have been approximately compensated by a contrast enhancement of object detail to about twice the original value. The influence of the perception time was placed in relation to an example of the influence of structured noise on the detection performance. This influence proved to be significantly greater than that of time. A comparison of the concept of "conspicuity" as defined by Revesz and Kundel was set in relation to the term "Auffälligkeit" ("distinctiveness") coined by Stender. It was established that the quality reserve QR after Borcke corresponds to "Auffälligkeit" as defined by Stender and should best be separated from image quality changes dues to the influence of structured noise on the detection of radiological abnormalities.

Humans

[Visual perception, reaction time and their alteration under the influence of alcohol in patients with remote sequelae of closed cranio-cerebral trauma].

In patients with remote sequalae of closed brain injuries the author examined the time of perception of letter stimula by the aid of a technique of reverse masking, the time of motor reactions to simple and letter stimula and changes of these temporary parameters under the influence of small doses of alcohol (60 ml 40 degrees alcohol). The time of perception and time of motor reactions to a simple stimula were practically identical to those in normals. The time of motor reactions to aletter stimula was higher than to a simple one and in patients significantly higher than in normals. Under the influence of alcohol the time of perception and motor reactions increase in conditions of letter distinguishing. These facts permit to consider that alcohol in such patients makes the processing of information in the CNS slower and most strongly influences the central cortical processes.

Adult

Probing the cognitive representation of musical time: structural constraints on the perception of timing perturbations.

To determine whether structural factors interact with the perception of musical time, musically literate listeners were presented repeatedly with eight-bar musical excerpts, realized with physically regular timing on an electronic piano. On each trial, one or two randomly chosen time intervals were lengthened by a small amount, and the score. The resulting detection accuracy profile across all positions in each musical excerpt showed pronounced dips in places where lengthening would typically occur in an expressive (temporally modulated) performance. False alarm percentages indicated that certain tones seemed longer a priori, and these were among the ones whose actual lengthening was easiest to detect. The detection accuracy and false alarm profiles were significantly correlated with each other and with the temporal microstructure of expert performances, as measured from sound recordings by famous artists. Thus the detection task apparently tapped into listeners' musical thought and revealed their expectations about the temporal microstructure of music performance. These expectations, like the timing patterns of actual performances, derive from the cognitive representation of musical structure, as cued by a variety of systemic factors (grouping, meter, harmonic progression) and their acoustic correlates. No simple psycho-acoustic explanation of the detection accuracy profiles was evident. The results suggest that the perception of musical time is not veridical but "warped" by the structural representation. This warping may provide a natural basis for performance evaluation: expected timing patterns sound more or less regular, unexpected ones irregular. Parallels to language performance and perception are noted.

Acoustic Stimulation

The perception of time in scale model environments.

It has been claimed that when subjects observe differently-scaled model environments their experience of temporal duration is compressed relative to standard clock time in the same proportion as the scale of the model being observed. A series of experiments is reported in which subjects made judgements of duration while observing model environments of different scale. In each experiment, two similar model environments of different scale were presented. Three different kinds of model were used: scale model railways, sitting-room models, and abstract nonrepresentional models. Despite considerable individual variability, significant effects were obtained. Smaller scale was, up to a point, related to a compression of subjective time relative to clock time, although the effect was nowhere near as great as that previously reported. Also, when scale was reduced beyond a certain point the effect on judgements of duration was eliminated, or even reversed. It is suggested that the effect of time compression is related to differences in the density of the information to be processed in environments of different scale, and that there may be an optimum value for information density related both to the scale and to the type of environment.

Adolescent