Apparent time interval of visual stimuli is compressed during fast hand movement

Abstract

The influence of body movements on visual time perception is receiving increased attention. Past studies showed apparent expansion of visual time before and after the execution of hand movements and apparent compression of visual time during the execution of eye movements. Here we examined whether the estimation of sub-second time intervals between visual events is expanded, compressed, or unaffected during the execution of hand movements. The results show that hand movements, at least the fast ones, reduced the apparent time interval between visual events. A control experiment indicated that the apparent time compression was not produced by the participants' involuntary eye movements during the hand movements. These results, together with earlier findings, suggest hand movement can change apparent visual time either in a compressive way or in an expansive way, depending on the relative timing between the hand movement and visual stimulus.

Fig 1. Schematic illustration of the experimental setup and time course.

(A) Experimental setup. (B) Time course of a stimulus for the experimental conditions.

Fig 2. Psychometric functions for the four conditions obtained for participant T. Y.

Filled circles and solid lines show the raw data and fitted psychometric curves, respectively.

Fig 3. The results in the main experiment (n = 7).

(A) The means of the PSEs. Error bars denote the standard errors. (B) The means of the JNDs. Error bars denote the standard errors.

Fig 4. The PSEs and JNDs in the supplementary experiment (n = 3).

Symbols indicate individual data points and error bars denote the 95% confidence interval calculated by bootstrap method [22]. The trials whose RMSE of eye movement exceeded the threshold were excluded from data analysis. The numbers at each data point indicate the rate of the number of sample data used to analyze all sample data (%). 100 (%) means that all 60 sample data were used in data analysis.