抄録
Mere exposure effect was first proposed by Zajonc (1968) as a phenomenon that "the repeated exposure of a stimulus object to an individual seems to enhance his attraction to the object". We tried to measure brain activity when MEE is occurring by comparing BOLD signal change when subjects made a choice according to preference between 2 stimuli; one was pre-exposed (subliminal exposure) to subjects and the other was novel. The preference ratio of this choice (preference judgment: PJ) was 57.8±12.7% for pre-exposed figures and higher than chance level (p=.03). As a control, subjects made a choice depending on whether they remembered stimuli (memory judgment: MJ).The different brain regions were activated in PJ and MJ. In PJ, bilateral insular cortices were activated in addition to a part of prefrontal and parietal cortices. In MJ, parts of occipital, parietal, prefrontal cortical areas and left insular cortex were activated. The right prefrontal region (inferior frontal gyrus) showed higher activity during PJ than MJ, and this region is supposed to be responsible for "the judgment to choose preferred stimuli". In contrast, a region that showed higher activity when subjects chose pre-exposed stimuli rather than novel stimuli was right insula. This region may be related to attraction to pre-exposed stimuli. [J Physiol Sci. 2007;57 Suppl:S168]
