No evidence of hemispheric facilitation following the induction of negative and positive affect

A dichotomy is thought to exist between the hemispheres whereby the right hemisphere is specialized for the processing of negative emotions and the left hemisphere is specialized for positive emotions. Van Strien and Morpurgo (Neuropsychologia, 1992, 30, 845-848) demonstrated that the activation of negative and positive emotional states resulted in the allocation of attentional resources to the contralateral hemispace. In the present experiment we sought to replicate this effect and improve upon certain methodological features of the experiment. The effect of positive and negative emotions on performance in the left and right visual fields was investigated in 30 dextral students. Positive and negative emotional states were generated by presenting subjects with an emotive word prior to each trial and subsequently requiring them to use that word within a sentence. Performance within the left and right fields was measured using a gap detection task which was neutral in relation to functional asymmetry. No evidence of right or left visual field facilitation was found for the positive or negative conditions, respectively. These results are not interpreted as a refutation of hemispheric specialization for emotional valence. Instead, they are seen to highlight the frailty of hemispheric facilitation effects.