An optimal adjustment procedure to minimize experiment time in decisions with multiple alternatives.

Decisions between multiple alternatives typically conform to Hick's Law: Mean response time increases log-linearly with the number of choice alternatives. We recently demonstrated context effects in Hick's Law, showing that patterns of response latency and choice accuracy were different for easy versus difficult blocks. The context effect explained previously observed discrepancies in error rate data and provided a new challenge for theoretical accounts of multialternative choice. In the present article, we propose a novel approach to modeling context effects that can be applied to any account that models the speed-accuracy trade-off. The core element of the approach is "optimality" in the way an experimental participant might define it: minimizing the total time spent in the experiment, without making too many errors. We show how this approach can be included in an existing Bayesian model of choice and highlight its ability to fit previous data as well as to predict novel empirical context effects. The model is shown to provide better quantitative fits than a more flexible heuristic account.