Figure 2.
Directly conditioned and unconditioned responses on day 2 of the experiment. (A) Pupil responses to CS+ and CS− did not differ in block 1, but diverged after the predictive associations were learned over the course of blocks 2 and 3, indicating successful threat acquisition. (B) Pupil responses to the US+ did not habituate—they remained consistently higher than to US− throughout the experiment, even though pupil responsiveness gradually decreased over learning blocks. Error bars represent 95% confidence intervals. Asterisks indicate statistically significant differences between conditions (*P < 0.05, **P < 0.01, and ***P < 0.001).
