Figure 4.

Increased decision thresholds and delayed urgency signals in the high compulsive group in fixed condition. a Decision thresholds indicate the difference in evidence needed for making a decision. The thresholds collapse as a function of sampling, in line with an increasing urgency signal found in perceptual decision making^{36, 39}. Importantly, the decision threshold in the fixed condition collapses significantly earlier in the low compulsive group, indicating that high compulsive subjects maintain a higher decision criterion for longer and consequently sample more information before making a decision. Decision threshold differences in the decreasing condition did not reach significance (lower panel). Green lines indicates decision thresholds of an optimal model. The initial rise of the thresholds reflects the maximal evidence difference possible at this stage (e.g., maximal evidence difference at Stage 2 is 2). b The urgency to choose, here cast as subjective costs for sampling, for the high compulsive group escalates later in the fixed condition. This is apparent in the fixed condition (upper panel) from the 10^th draw onwards, but not in the decreasing condition (lower panel)