Working memory and spatial judgments: Cognitive load increases the central tendency bias

Previous work demonstrates that memory for simple stimuli can be biased by information about the category of which the stimulus is a member. Specifically, stimuli with values greater than the category’s average tend to be underestimated and stimuli with values less than the average are overestimated. This is referred to as the central tendency bias. This bias has been explained as an optimal use of both noisy sensory information and category information. In a largely separate literature, cognitive load experiments attempt to manipulate the available working memory of participants in order to observe its effect on choice or judgments. In three experiments, we demonstrate that participants under a high cognitive load exhibit a stronger central tendency bias than when under a low cognitive load. Although not anticipated at the outset, we also find that judgments exhibit an anchoring bias.