Mental time line distortion in right-brain-damaged patients: Evidence from a dynamic spatiotemporal task.

Abstract

Time is an elusive phenomenon that is difficult to grasp with our senses. Recent work has shown how spatial representations often lie beneath temporal ones, as shown by a family of spatiotemporal congruency effects. For instance, individuals who have been exposed to left-to-right orthographic systems are better at judging short durations with their left effector and long durations with their right effector than vice versa, a phenomenon known as the spatial-temporal association of response codes (STEARC) effect. In the present neuropsychological study, we aimed to provide evidence that spatial attention mechanisms play a crucial role in generating this spatially organized mental time line. A group of 13 patients suffering from right hemisphere lesions with different degrees of spatial neglect signs and a control group of 15 age- and education-matched neurologically healthy participants were administered a unimanual version of a spatiotemporal compatibility task (STEARC task). The main results showed that the more a patient suffered from spatial neglect signs, the smaller the accuracy difference was between the left and right side responses for short durations. These findings corroborate the hypothesis that the presence of disorders in spatial attention affects the left-to-right mental time line representation, especially in its leftward segment, proportionally with the amount of deficit. This study therefore suggests the critical role of spatial attention for the emergence of a spatial representation of time durations.