Motor preparation and attentional benefits: dependencies on the number of possible saccade targets
43.3027, Monday, 18-May, 8:30 am - 12:30 pm, Banyan Breezeway
Michael Puntiroli1, Dirk Kerzel1, Sabine Born1,2; 1Faculté de Psychologie et des Sciences de lEducation, Université de Genève, Switzerland, 2Laboratoire Psychologie de la Perception, Université Paris Descartes, France
Growing evidence suggests movements are prepared through widespread and complex modulation in multiple brain centers, where inhibitory components assure execution is not triggered prematurely (Cohen, Sherman, Zinger, Perlmutter & Prut, 2010). It has been suggested that preparing an eye movement towards few possible targets, compared to many, results in longer latencies because of the activation of these inhibitory components (Lawrence, John, Abrams & Snyder, 2008). In contrast, Belopolsky & Theeuwes (2009) suggest that attending to a location that has a high probability of being a saccade target, because of only few available options, results in the activation of the oculomotor system and facilitation. Our goal was to clarify this discrepancy and to measure attention at object locations when saccade target alternatives were few or many. While the total number of presented stimuli was kept constant (twelve circles), the saccade target could be at only two possible circle locations in the few alternatives condition, while the many alternatives condition featured six options. We employed a dual-task paradigm, primarily requiring the rapid execution of saccades to the only circle that became the target colour. The secondary task was to discriminate an asymmetric cross flashed at one of the circles. Our results show that slower saccade initiation is found when the possible saccade targets are two, indeed suggesting inhibitory motor components may be at play. However, the discrimination scores show that perception at the saccade target and the (never fixated) alternative saccade target were both facilitated compared to an attended control location. This suggests motor suppression may not necessarily affect perception. Recently Dhawan, Deubel & Jonikaitis (2013) showed that inhibition of saccades led to perceptual suppression, while in our study perception appeared unaffected. We put forward attention-based interpretations focusing on attentional window size and fuzzy loci leading to more stimulus-driven eye movements.