Learning the lie of the land: How people construct mental representations of distributions

An unexamined assumption in many studies of learning and decision making is that people learn underlying probability distributions. However, the acquisition of distributional knowledge is rarely the focus of investigations. We report five experiments (N = 580 adults) that provide this focus and highlight the factors that impact people’s ability to accurately learn and reproduce underlying distributions. We find that people accurately reproduced the distribution only when either the environmental signal is strong (e.g., discrete bimodal distributions) or sufficient cues are provided to aid construction of mental representations (e.g., items from the modes in a noisy bimodal distribution are presented in different colors). We interpret these results in terms of participants testing and learning discrete rules corresponding to salient features of the environment rather than spontaneously representing entire distributions. As such, the findings challenge strong assumptions about the role of probability distribution knowledge in explanations of learning and decision making.