Atención exógena y endógena a estímulos emocionalesCorrelatos conductuales y electrofisiológicos

Résumé

Previous data indicate that emotional stimuli are prioritized during both endogenous and exogenous attention. However, this evidence was obtained from studies exploring each of the two attentional modalities separately, and further proof is needed of this advantage when both attentional systems are simultaneously dealing with emotional events. Thus, the present Thesis explored this issue through behavioral and electrophysiological measures. The main purposes, always regarding emotional stimulation, were i) to explore how the endogenous-exogenous competition is resolved at the behavioral level and whether there is any advantage of one system over the other; ii) to disentangle the neural time course of these concurrent attentional processes, discovering if they are reflected in the event-related potential (ERP) in a parallel manner or in a serial order; iii) to analyze how stimulus valence and arousal modulate competing endogenous and exogenous attention. To that aim, two experiments employing concurrent but distinct target-distracter tasks were carried out. In Experiment 1, the task was fully randomized, while, in Experiment 2, emotional target conditions were presented in blocks, in order to facilitate the generation of affective contexts that resemble what occurs in real situations, in which endogenous attention is often directed towards long-lasting events. In the two experiments, both distracters (potentially capturing exogenous attention) and targets (to which endogenous attention was directed) were emotionally negative, neutral, and positive pictures. Behavioral results showed sensitivity to the emotional content of targets rather than of distracters. At the neural level, ERPs indicated an affective modulation in both attention modalities with no clear advantage of any of them. These ERP effects were reflected in a serial manner, and the effects did not show any significant endogenous-exogenous interactions, in favor of a certain functional segregation of both attentional systems in response to emotional stimuli. These effects were potentiated when a context was generated through blocked presentation of emotional targets. No advantage of the valence or arousal dimensions of pictures was observed.