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

OBJECTIVE: 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. METHOD: 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). RESULTS: 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. CONCLUSIONS: 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.