Laura Gabriela, F. & Siéroff, E.
Laboratoire de Psychologie et Neuropsychologie Cognitives CNRS FRE 3292. Université Paris Descartes. Paris, France.
A crucial component in attentional control is the ability to prepare to the occurrence of an upcoming stimulus. LaBerge, Auclair, and Siéroff (2000) have developed the Attentional Preparatory Test (APT), which measures the ability of subjects to modulate (enhance) their preparatory attention to a target location when the probability of a distractor occurrence varies in several blocks (0%, 33%, 67%). We investigated the role of each hemisphere in preparatory attention, using a lateralized version of the APT, with targets in the right (RVF) or left (LVF) visual fields. Four experiments were conducted, varying the instructions (explicit or not about the proportion of trials with distractor) and the task (detection, localization). Although response times in the LVF were slower when distractors were present, without difference between the 33% and 67% blocks, response times in the RVF showed a linear increase as a function of the proportion of distractor trials (with the explicit instruction and regardless of the task). The results are explained by a differential hemispheric modulation of preparatory attention directed to the target and/or distractor, and are in agreement with a frequency matching strategy in the left hemisphere.