Figure 2.

Average standardized startle-blink EMG magnitudes at generalization test, by group, for conditioned stimuli paired (CS+) and unpaired (CS−) with shock, generalization stimuli (GS₁, GS₂, GS₃, GS₄), and intertrial intervals (ITIs). The dotted lines reflect linear decreases in startle from CS+ to CS− with which to visualize the deviation of gradients from linearity. Such deviations reflect a significant quadratic component in the generalization gradient of healthy comparison subjects (p=0.001) but not patients with panic disorder (p=0.62). The circled data points indicate stimulus classes for which startle is potentiated relative to the CS− (at the Hochberg-adjusted p value) for each group.