Humans use different statistics for sequence analysis depending on the task

Abstract

Despite its long history (Luce, 1986) the study of sequential effects has mostly been confined to simple binary tasks such as two-alternative forced choice tasks (2AFC). Here we present experimental results from a choice task with three rather than two alternatives (3AFC) as well as a novel model that can explain them. We find that humans change the statistics they use to analyse a sequence depending on the task constraints, relying on first-order transition probabilities in a 2AFC but event relative frequencies (i.e., zeroth-order transition probabilities) in a 3AFC.