TY - JOUR

T1 - Time-varying decision boundaries

T2 - insights from optimality analysis

AU - Malhotra, Gaurav

AU - Leslie, David S.

AU - Ludwig, Casimir J. H.

AU - Bogacz, Rafal

PY - 2018/6

Y1 - 2018/6

N2 - The most widely used account of decision-making proposes that people choose between alternatives by accumulating evidence in favor of each alternative until this evidence reaches a decision boundary. It is frequently assumed that this decision boundary stays constant during a decision, depending on the evidence collected but not on time. Recent experimental and theoretical work has challenged this assumption, showing that constant decision boundaries are, in some circumstances, sub-optimal. We introduce a theoretical model that facilitates identification of the optimal decision boundaries under a wide range of conditions. Time-varying optimal decision boundaries for our model are a result only of uncertainty over the difficulty of each trial and do not require decision deadlines or costs associated with collecting evidence, as assumed by previous authors. Furthermore, the shape of optimal decision boundaries depends on the difficulties of different decisions. When some trials are very difficult, optimal boundaries decrease with time, but for tasks that only include a mixture of easy and medium difficulty trials, the optimal boundaries increase or stay constant. We also show how this simple model can be extended to more complex decision-making tasks such as when people have unequal priors or when they can choose to opt out of decisions. The theoretical model presented here provides an important framework to understand how, why, and whether decision boundaries should change over time in experiments on decision-making.

AB - The most widely used account of decision-making proposes that people choose between alternatives by accumulating evidence in favor of each alternative until this evidence reaches a decision boundary. It is frequently assumed that this decision boundary stays constant during a decision, depending on the evidence collected but not on time. Recent experimental and theoretical work has challenged this assumption, showing that constant decision boundaries are, in some circumstances, sub-optimal. We introduce a theoretical model that facilitates identification of the optimal decision boundaries under a wide range of conditions. Time-varying optimal decision boundaries for our model are a result only of uncertainty over the difficulty of each trial and do not require decision deadlines or costs associated with collecting evidence, as assumed by previous authors. Furthermore, the shape of optimal decision boundaries depends on the difficulties of different decisions. When some trials are very difficult, optimal boundaries decrease with time, but for tasks that only include a mixture of easy and medium difficulty trials, the optimal boundaries increase or stay constant. We also show how this simple model can be extended to more complex decision-making tasks such as when people have unequal priors or when they can choose to opt out of decisions. The theoretical model presented here provides an important framework to understand how, why, and whether decision boundaries should change over time in experiments on decision-making.

KW - Decision-making

KW - Decreasing bounds

KW - Optimal decisions

KW - Reward rate

KW - CHOICE REACTION-TIMES

KW - DIFFUSION-MODEL

KW - DEFERRED DECISION

KW - DISCRIMINATION TASK

KW - PRIOR PROBABILITY

KW - REWARD RATE

KW - INFORMATION

KW - STRATEGIES

KW - ACCURACY

KW - BEHAVIOR

U2 - 10.3758/s13423-017-1340-6

DO - 10.3758/s13423-017-1340-6

M3 - Journal article

VL - 25

SP - 971

EP - 996

JO - Psychonomic Bulletin and Review

JF - Psychonomic Bulletin and Review

SN - 1069-9384

IS - 3

ER -