Two hundred images from the IAPS (P.J. Lang et al., 1999) were used—100 images from the upper 40% of arousal ratings (high- arousal images) and 100 images from the lower 40% (low- arousal images). Within each arousal category, pictures were divided equally into positive and negative valence groups (on the basis of the median valence rating within each arousal level). High-arousal stimuli depicted nudity, erotica, extreme sports, violence, bodily mutilation, insects, and snakes. Low-arousal stimuli included pictures of ordinary scenes, objects, people, and food. The high-arousal pictures had higher arousal ratings (M = 6.04, SE = 0.06) than the low-arousal pictures (M = 3.52, SE = 0.06), as confirmed with analysis of variance (ANOVA), F(1, 196) = 804.6, p < .0001. The positive pictures had higher valence ratings (M = 6.47, SE = 0.09) than the negative pictures (M = 3.5, SE = 0.09), F(1, 196) = 591.7, p < .0001. However, the Valence × Arousal interaction was significant for the valence ratings, F(1, 196) = 50.8, p < .0001; among high-arousal stimuli, positive pictures had higher valence ratings (M
