Spatial Representation of Time in Backspace

Abstract

Temporal information, numerical magnitude and space extension appear to share common representational mechanisms and be processed similarly in the brain. Evidence comes from the phenomenon of ‘pseudoneglect’, i.e. healthy persons’ orientation asymmetry toward the left side of space. Pseudoneglect is also evident along the mental number line which extends from small numbers on the left to large numbers on the right. In analogy to numbers, time is typically represented on a line extending from the left to the right side. It may thus be no surprise that pseudoneglect has been demonstrated in the temporal domain as well. Besides the perception of the space located anteriorly to our trunk (frontspace), we are able to represent the space behind us, which we cannot visually perceive (backspace). The translational model suggests a mapping of spatially defined information to the ipsilateral side of the egocentric reference frame in front- and backspace, while the rotational concept focuses on a 360° spatial representation around the midsagittal plane of the trunk. At the present stage of investigation, little is known about the representation of temporal information in backspace. In an attempt to fill this gap, we compared duration estimations of auditory stimuli in frontspace and backspace. Healthy right-handers were instructed to judge their duration relative to each other. We found a pseudoneglect-behavior not only in frontspace but also in backspace. The data are discussed in the context of common processing mechanisms for time, numbers and space and favor a translational over a rotational account for the representation of backspace. The results are further discussed with reference to potential consequences for the rehabilitation of hemispatial neglect.