The ‘whys’ and ‘whens’ of individual differences in thinking biases

Although human thinking is often biased, some individuals are less susceptible to biases than others. These individual differences have been at the forefront of thinking research for more than a decade. We organize the literature in three key accounts (storage, monitoring, and inhibition failure) and propose that a critical but overlooked question concerns the time point at which individual variance arises: do biased and unbiased reasoners take different paths early on in the reasoning process or is the observed variance late to arise? We discuss how this focus on the ‘whens’ suggests that individual differences in thinking biases are less profound than traditionally assumed, in the sense that they might typically arise at a later stage of the reasoning process.

Introduction

Since the 1960s, a myriad of studies in the cognitive sciences have demonstrated biases in human thinking – that is, systematic and predictable deviations from formal norms, such as the laws of logic, the theory of probability, or the axioms of rational choice 1, 2. In general, people have been shown to have a strong tendency to base their judgments on fast intuitive impressions [1]. Although this intuitive or so-called ‘heuristic’ thinking can sometimes be useful, it can also cue responses that conflict with formal norms and bias people's reasoning 1, 3, 4. Most individuals display these thinking biases, but people show substantial and consistent differences in their propensity to do so. These individual differences have been at the forefront of thinking and reasoning research for more than a decade 4, 5.

Cognitive scientists have proposed numerous answers to the question of why some individuals tend to produce biased responses, whereas others do not. In this article, we offer two perspectives on how to organize this literature. In a first section, we organize current research into three key positions, which assign different cognitive loci to thinking biases (storage failure, monitoring failure, inhibition failure). In a second section, we introduce a different, albeit closely related, organization of the literature. We suggest that, instead of focusing on why individuals differ, we may consider when they start to differ in the reasoning process. Although these two questions are highly intricate, we will suggest that they bring two equally useful perspectives on outstanding questions in thinking biases research. We will conclude, in particular, that considering the ‘whens’ of individual differences in thinking biases make these differences appear less profound than what their ‘whys’ would suggest. That is, individual differences in reasoning may typically arise at a late stage of the reasoning process, up until which all reasoners follow the same cognitive path.