Abstract:

According to the Motivational Dimensional Model of Affect, positive affects that varies in approach motivational intensity have diverse impacts on cognitive processes. Previous studies used the local-global visual-processing task and Navon task to examine the attentional consequences of approach-motivated positive affect, and demonstrated that positive affect which is high in approach-motivation reduced the breadth of attention, whereas low approach-motivated positive affect increased global attention. Most of these researches were done by measuring response time (RT). So far, however, relatively little is known about the neural mechanisms of this phenomenon. Studies of attention have suggested that attention operates at both early (sensory input) and late (response selection) processing stages. The high temporal resolution of event-related potentials (ERPs) allows for a more detailed analysis of the time course of attention processing. Therefore the present study used ERP technology and Flanker task to explore whether the effect of motivational intensity on the breadth of attention occurred at the early or the late attention processing stage. Twenty participants (six men and fourteen women) took part in this experiment. Pictures of dessert and scene were used to induce participants’ high and low approach-motivated positive affect. After viewing each picture, participants were asked to accomplish Flanker task, which was, respond to the central target letter by pressing a corresponding button. In 75% of the Flanker tasks, a white rectangular probe stimulus was presented on the left or right of the central letter. EEG activity was recorded during the whole process of the experiment. The results showed that, during the interval of 90~130 ms after Flanker letters onset, the Flanker letters with probe stimuli under high approach-motivated positive affect evoked smaller P1 than the low approach-motivated positive affect. It might suggest that high approach-motivated positive affect narrows the focus of attention during visual input stage. In addition, the Flanker letters under high approach-motivated positive affect evoked the more negative N2b component between 280 and 350 ms; however, at 400~600 ms, the low approach-motivated positive affect evoked a larger P3 component. These results indicated that the high approach-motivated positive affect enhanced the capability of interference suppression, and the participants under low approach-motivated positive affect would pay more attention to periphery stimulus. In sum, the emotional motivational intensity not only impacted the early stage of attention processing but also modulated the late attention processing.

Key words: positive affect, motivational intensity, attention, ERP