تداخل گذرا از عملکرد نیمکره راست به علت پردازش عاطفی اتوماتیک

We examined the effects of emotional stimuli on right and left hemisphere detection performance in a hemifield visual discrimination task. A group of 18 healthy subjects were asked to discriminate between upright and inverted triangles (target). Targets were randomly presented in the left or right visual hemifield (150 ms target duration). A brief emotional picture (pleasant or unpleasant; 150 ms stimulus duration) or neutral picture selected from the International Affective Picture System was randomly presented either in the same (47%) or the opposite (47%) spatial location to the subsequent target. Emotional or neutral stimuli offset 150 ms prior to the subsequent target. Subjects were instructed to ignore the pictures and respond to the targets as quickly and accurately as possible. Independent of field of presentation, emotional stimuli prolonged reaction times (P<0.01) to LVF targets, with unpleasant stimuli showing a greater effect than pleasant stimuli. The current study shows that brief emotional stimuli selectively impair right hemispheric visual discrimination capacity. The findings suggest automatic processing of emotional stimuli captures right hemispheric processing resources and transiently interferes with other right hemispheric functions.

Asymmetries in hemispheric involvement for several cognitive functions, most notably for language, have been demonstrated. However, rather than each hemisphere specializing in distinct cognitive processes, the cerebral hemispheres have been characterized as complementary and integrative processing systems [1]. While basic bilateral and complementary organization appears to be true also for emotional processing, neuropsychological [9], electrophysiological [5] and [11], neuroimaging [3] and behavioral [23] evidence supports cerebral asymmetries relating to perceiving, expressing, experiencing and responding to emotions. An overall right hemispheric bias for mediating the perception and expression of emotion has been suggested, while the lateralization of functions subservient to emotional experience seems to depend upon the valence of the emotions, with the left hemisphere being more engaged in pleasant and the right hemisphere in unpleasant emotions (for reviews see Refs. [10] and [21]). While the evidence for emotion-related asymmetries is robust, there is limited evidence on how this asymmetric hemispheric activation affects other lateralized brain processes.