Authors:

CALDER, A.J., EWBANK, M.P., RAMPONI, C. & BARNARD, P.J.

Reference:

Year of publication:

2007

CBU number:

6558

Abstract:

Emotional events attract attention and are better remembered than non-emotional events. Dimensional models of emotion suggest that attention and memory are primarily modulated by arousal and valence. The amygdala has been identified as a central structure in these functions, and is particularly sensitive to highly arousing and unpleasant stimuli. However, our recent behavioural data suggests that factors other than valence and arousal may provide a better account of the amygdala’s response to emotional images. When controlling for arousal and valence, the subjective ratings of an image’s immediate impact (a term often used in visual media for particularly eye-catching pictures), was the best predictor of whether the image was subsequently remembered or not. We sought to explore how impact would influence activity within brain regions involved in emotion processing, and in particular the amygdala. In an event-related fMRI study participants viewed high and low impact negative emotional images that were matched for valence, arousal, visual distinctiveness and other factors. We found an increased amygdala response to high impact images compared to both low impact and neutral images. In contrast, we found no difference in amygdala response between low impact and neutrally valent images (despite low impact images being rated as more negative). Our results suggest that amygdala sensitivity to emotional stimuli is not a simple function of arousal and negative valence. Rather, it responds to differences in how cogent or salient material is, and impact may provide a sensitive measure of amygdala reactivity to this dimension.