Abbreviations: CS+=reinforced conditioned stimulus; CS-=non-reinforced conditioned stimulus.

Figure 2: Mean ± SE difference score (calculated as the difference in startle magnitude between the CS and NA) during late fear conditioning across Trial Type and diagnostic groups. Only the Control (neither diagnosis) and the SUDs only groups show significantly higher startle to the CS+ than the CS-. The two SUDs groups have lower fear-potentiated startle to the CS+, and the two PTSD groups have higher startle to the CS-. **=p<.001; ¥=p<.05 main effect of SUD; #=p<.05 main effect of PTSD.