Abstract
The categorization of facial expressions is impaired when central attentional resources are shared with an overlapping task (Tomasik et al., 2009). Using the psychological refractory period (PRP) dual-task paradigm, we verified if unavailability of central resources precludes the utilization of normal visual strategies. Twenty subjects took part in the study. In the first task (T1), they categorized a sound (150ms) as either low (200Hz or 400Hz) or high (800Hz or 1,600Hz) frequency. In the second task (T2), participants categorized the facial expressions of anger, disgust, fear, happiness, sadness, and surprise taken from the Karolinska face database (Lundqvist, Flykt & Öhman, 1998). External facial cues were hidden with an oval that blended with the background. Faces were sampled with Bubbles (Gosselin & Schyns, 2001) and presented for 150ms. T1 and T2 presentation was separated by a stimulus onset asynchrony (SOA) of either 300ms (central resource overlap) or 1,000ms (no overlap). Participants were instructed to answer as rapidly and as accurately as possible to both tasks, and not to wait for T2 onset before answering to T1. We performed a linear regression of Bubbles' coordinates on T2 performance. Statistical significance was determined with the Stat4CI toolbox (Chauvin et al., 2005). The categorization of angry, sad, fearful, and surprised expressions strongly correlated with utilization of both eyes and the mouth, at short and long SOAs (Z> 3.4, p< .05). Utilization of the left eye, however, was significantly reduced at short, relative to long SOA (Z> 2, k> 2,347 pixels, p< .05). Interestingly, whereas participants showed a bias favoring the left side of the face at long SOA, they favored the right side at short SOA. Participants always fixated the center of face stimuli. Thus, these results could be hinting at hemispheric differences in sensitivity to the modulation of central attentional resources.
Meeting abstract presented at VSS 2017