Prior physical exertion modulates allocentric distance perception: a demonstration of task-irrelevant cross-modal transfer

Abstract

Physical exertion has been previously shown to influence distance perception in the egocentric framework. In this study, we show that physical exertion influences allocentric distance perception. Twenty healthy volunteers made allocentric line length estimates following varying levels of physical exertion. Each participant was presented with 30 different line lengths ranging from 1 to 12 cm, and each length was presented three times. Each line presentation was preceded by the participant exerting one of the following three levels of their maximal voluntary force (MVF): 20, 50, or 80 % MVF using their hand in the pinch force task. Psychometric curves were obtained for the lines perceived as 'long' following each of the three force levels. Lines that were perceived as 'short' following 20 and 50 % MVF were perceived as 'long' following 80 % MVF; that is, there was a significant leftward shift in the psychometric curve following 80 % MVF when compared to 20 and 50 % MVF. Here, we demonstrate that physical exertion influences perception of distances in the allocentric framework. We discuss our findings with respect to cross-modal interactions, fatigue physiology, peri- and extra-personal space interactions.

Keywords: Allocentric; Distance estimation; Perception; Physical exertion.

Fig. 1

In a, the total number of ‘long’ responses is shown on the y-axis while the length of the presented line is shown on the x-axis. The light grey circular symbols represent the responses that were given following 20 % force production, the dark grey square symbols represent responses following 50 % force production, and black triangular symbols represent those following 80 % force production. In b, the fitted psychometric curves of the three force levels are shown. A significant difference is seen between the 80 and 20 % curves and likewise with 50 % curves