Influence of individual differences in the Behavioral Inhibition System and stimulus content (fear versus blood-disgust) on affective startle reflex modulation

Inconsistencies among affective startle reflex modulation studies may be due to differences in the startle potentiation produced by the specific content of the images used, to individual differences in sensitivity to negative stimuli, or to the interaction of both factors. To explore this interaction, 52 undergraduates obtaining extreme scores on a self-report measure of the Behavioral Inhibition System (BIS) participated in an affective startle reflex modulation paradigm. A significant interaction between BIS group (high versus low) and image content emerged from the MANOVA. Comparing startle magnitude between fear and pleasant images, low BIS participants did not seem to show startle potentiation, whereas high BIS participants did. Both groups displayed potentiated startle during blood-disgust images. The present results suggest the importance of considering personality variables and their interaction with image content in the affective startle modulation paradigm.