Figure 1

(A) Overview of the experimental protocol. Upper panel: Circles of increasing sizes were used as generalization stimuli, the middle circle was used as the conditioned stimulus. Middle panel: Schematic representation of the experimental design. Lower panel: Trial flow during the generalization phase. A circle was presented and participants had to categorize the stimulus as same or different as the circle presented during the acquisition phase. Next, US expectancy was recorded. In case of a reinforced CS trial, a painful electrocutaneous stimulus was presented after 8 seconds. (B) Mean US expectancy data across acquisition trials for the different groups. (C) Mean difference in CS startle amplitudes during acquisition and overall ITI startle amplitudes. Error bars represent standard errors.