Fixation patterns in simple choice reflect optimal information sampling

Simple choices (e.g., eating an apple vs. an orange) are made by integrating noisy evidence that is sampled over time and influenced by visual attention; as a result, fluctuations in visual attention can affect choices. But what determines what is fixated and when? To address this question, we model the decision process for simple choice as an information sampling problem, and approximate the optimal sampling policy. We find that it is optimal to sample from options whose value estimates are both high and uncertain. Furthermore, the optimal policy provides a reasonable account of fixations and choices in binary and trinary simple choice, as well as the differences between the two cases. Overall, the results show that the fixation process during simple choice is influenced dynamically by the value estimates computed during the decision process, in a manner consistent with optimal information sampling. Author summary Any supermarket shopper is familiar with the problem of choosing between a small number of items. Even these "simple choices" can be challenging because we have to think about the options to determine which one we like most, and we can't think about all of them at once. This raises a question: what should we think about-and for how long should we think-before making a decision? We formalize this question as an information sampling problem, and identify an optimal solution. Observing what people look at while making choices, we find that many of the key patterns in their eye fixations are consistent with optimal information sampling.