PT  - JOURNAL ARTICLE
AU  - Kobe Desender
AU  - Annika Boldt
AU  - Tom Verguts
AU  - Tobias H. Donner
TI  - Post-decisional sense of confidence shapes speed-accuracy tradeoff for subsequent choices
AID  - 10.1101/466730
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 466730
4099  - http://biorxiv.org/content/early/2018/11/09/466730.short
4100  - http://biorxiv.org/content/early/2018/11/09/466730.full
AB  - In the absence of external feedback about decision outcomes, agents need to adapt their decision policies based on their internal evaluation of their own performance (i.e., decision confidence). We hypothesized that agents use decision confidence to continuously update the tradeoff between the speed and the accuracy of their decisions: When confidence is low on one trial, the decision-maker commits to a choice only after having accumulated more evidence on the next trial, leading to slower but more accurate decisions. Bounded accumulation models of decision-making provide a formal framework for testing this idea. Such models conceptualize the decision process as the accumulation of noisy sensory evidence towards one of two decision bounds, the height of which sets the speed-accuracy tradeoff. Low confidence on one trial should then lead to an increase of the decision bound on the next. We tested this prediction by fitting a bounded accumulation model to behavioral data from three different perceptual tasks, which entailed a binary choice with subsequent confidence rating. Indeed, decision bounds depended on the reported confidence about the correctness of the previous choice. Decision bounds were particularly strongly increased after participants were relatively certain to have made an error. The increase in decision bound was predicted by one post-decisional EEG signal sensitive to confidence and error perception (the so-called error positivity) peaking over centro-parietal cortex, but not by another (earlier, mid-frontal) post-decisional EEG signal (the error-related negativity). We conclude that the brain uses a subset of its post-decisional confidence signals for the ongoing adjustment of decision policies.