Time perception and the Stroop task.

Three experiments were conducted to assess the effects of the Stroop task (color-word incongruities) on observers' estimates of 30-sec. inspection periods. The experiments differed in psychophysical procedure; the three classic methods of production, reproduction, and verbal estimation were employed. Observers underestimated the passage of time, compared to doing nothing, when they were engaged on the Stroop task. However, judgments of duration on the Stroop task were shorter than those made in the control condition of naming color dots only when the method of production was employed. These findings are similar to results with mental arithmetic tasks and contribute to the understanding of the relationship between cognitive processing and time perception.

Auditory and visual differences in time perception.

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.

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.

Effects of motor and verbal practice on the Stroop task.

Motor responses to the Stroop task have been largely ignored despite almost a century of active research on verbal responses to the test. The Stroop task maximizes verbal interference by asking subjects to ignore the stimulus word, e.g., red, and respond to the color of the ink in which the work is printed, e.g., blue. A few recent studies have suggested that motor responses (pressing color-coded buttons) might minimize this interference phenomenon presumably via bypassing the usual verbal processing mechanisms. This study compared motor and verbal responses and provided extensive practice. There were no over-all significant differences between motor and verbal responding although motor responses were faster. Significant practice effects and a significant interaction of response mode by practice suggest that motor responding reacts more rapidly to practice effects.

Color perception and deafness: college-level comparisons.

The performance of three groups of college-level subjects, deaf students, normal-hearing students, and Art students, were compared on nine tests involving color perception and color-verbal materials including (a) Color-Form Sorting, (b) Color-Form Pointing, (c) Color-Word Meaning, (d) Color-Pair Preferences (N=3), and (e) Color-Word Interference (N=3). Color perception differences between the deaf and the hearing groups were not substantiated: deaf and hearing groups differed only on tests involving verbal materials. The Deaf differed more from the Art students than from the Hearing.

Intensity of motion sickness symptoms as a function of apparent autonomic balance.

Twenty volunteer male college students were exposed to motion picture films which reliably elicit symptoms of motion sickness. Those Ss with relatively higher apparent sympathetic nervous system dominance showed significantly smaller autonomic reactions to the film. It was concluded that increased sympathetic tone tended to the film. It was concluded that increased sympathetic tone tended to reduce autonomic reactions to motion sickness stimuli. It was suggested that the sympathetic nervous system symptoms that usually occur in motion sickness are actually defensive reactions rather than symptoms of nausea.

The relationship between life change and relative autonomic balance.

The frequency of life changes, as measured by questionnaires, is reported to increase prior to illness onset. Each event presumably adds to the accumulating amount of adaptive stress that confronts the individual. Total frequencies, or weighted scores, are considered important etiological factors in the illness. A more direct measure of stress is the A test of relative autonomic balance between sympathetic and parasympathetic systems. To assess the relationship between these two measures 76 undergraduates were given both a life change questionnaire and the A test. Significant negative correlations were expected because both low A and high life change scores supposedly measure adaptive stress. No significant correlations were obtained; female Ss (N = 41) reported significantly more life changes than did male Ss (N = 26). The etiological value of life changes is scrutinized, and it is hypothesized that these questionnaires may be effective to identify stress only in populations that already have existent active or latent disease processes.

Information processing and estimation of short time intervals.

Duration estimates were assessed by the method of reproduction with filled reproduction intervals. Mental arithmetic, reading and mirror-image drawing were used in pairs as initial and/or reproduction tasks. All nine possible pairs of tasks were used in a 9 X 5 X 5 mixed design with five Ss per task pair and five interruption intervals for each initial task. Results indicated that, when arithmetic was used as the initial task, Ss underestimated the duration of the initial interval. When arithmetic was used as the reproduction task, Ss overestimated the duration of the initial interval. A significant correlation was obtained between arithmetic outputs and the lengths of the duration estimates. Results are interpreted as supportive of Burnside's (1971) interpretation of Ornstein's (1969) storage-size hypothesis.