Depression Induced Quantity Estimation Bias Manifests Only Under Time Constraints

Abstract

Here, we assess whether quantity representations are influenced by the perceptual biases hypothesized to manifest in depressive individuals. In contrast to this clinical model, several prominent models of numerical cognition assume that quantity representations are abstract, and therefore are independent of the items that are being quantified. If this is the case, then the depression induced perceptual biases should not manifest with respect to the perception of quantity. We tested these predictions in two experiments in which we presented participants with a number-line with a tick mark that indicated the time until a positive, neutral, or negative event. The participant’s task was to estimate the quantity of time indicated by the tick mark. In both experiments, we assessed participants’ BDI-II score. To assess the role of controlled, strategic processing on the manifestation of these biases, we manipulated the amount of time that participants were able to study the number-line prior to responding. In Experiment 1, we attempted to motivate participants to respond quickly voluntarily. The results revealed no influence of time pressure on participants’ RTs, nor any relation between quantity bias and depression. In Experiment 2, we restricted the amount of time participants could spend viewing the number-line. The results revealed estimation biases consistent with the perceptual biases predicted by Beck’s cognitive theory of depression for the short presentation times. These findings (1) confirm that level of depression is linked to the predicted perceptual biases of quantity and (2) implicate controlled processing in the masking of perceptual bias.