Deciding when to decide: how recency, urgency, risk, and bias shape human sequential decision-making - a case study across the obsessive–compulsive spectrum
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Deciding when to stop gathering information and commit to a choice is a fundamental challenge in decision-making under uncertainty. Normative characterizations such as Partially Observable Markov Decision Processes (POMDPs) prescribe mathematically optimal stopping rules; however, human evidence gathering systematically departs from optimality. Pathological departures – such as the excessive indecisiveness characteristic of obsessive-compulsive disorder (OCD) – offer an important opportunity to investigate the cognitive mechanisms involved in stopping. We extend a POMDP framework to incorporate key candidate suboptimalities: a biased prior belief, transient evidence exaggeration, progressive forgetting, boosted costs of error, temporal regulation (patience and urgency), and misperception of a deadline. We evaluate this model in a pre-existing dataset comprising 105 participants spanning healthy controls, generalised anxiety disorder, and the OCD spectrum performing an information gathering task with controlled, stochastic, deadlines. Model comparison reveals that human sequential choices are broadly governed by subjective risk penalties and time-dependent urgency, with a smaller and less certain contribution from an over-weighting of recent evidence, which a random-effects comparison does not support at the population level. Individuals differ in how that overweighting is implemented: in one deadline condition, subjects divide almost evenly between models carrying a transient exaggeration of the newest sample, models carrying progressive forgetting of older evidence, and models carrying no recency mechanism at all. Crucially, while risk sensitivity and choice stochasticity act as shared mechanisms across conditions, mechanisms such as belief bias and patience are more variable. Finally, using OCD as a clinical case study, we demonstrate that simulating choices from the fitted exaggeration model reproduces model-agnostic regression signatures of clinical indecision, which the forgetting and no-recency accounts do not. These findings offer a generative foundation for dissecting clinical departures in information gathering across the obsessive-compulsive spectrum.
Author summary
When people gather information before deciding, how do they choose when to stop, how does this depart from the theoretically optimal strategy, and how are the answers to these questions different in disorders involving indecision such as obsessive-compulsive disorder (OCD)? We reanalyze data from a recent study in which a large number of participants, including some on an OCD spectrum, exhibited a specific suboptimality. We examine the relative importance of a small number of interpretable departures from optimality, including a biased prior, over-weighting of most recent evidence, exponential forgetting of old evidence, excess costs for an incorrect choice, and a patience and urgency signal.
