Dysphoria and memory for emotional material: A diffusion-model analysis

Depression-related differences in memory for emotional material are well established, but recognition memory and lexical decision tasks often fail to produce consistent results. The null results from these tasks could be due to inadequacies in traditional analyses rather than the absence of effects. In particular, analyses of accuracy or mean reaction times rely on only a fraction of the behavioural data and are sensitive to individual differences in response biases. The diffusion model addresses these limitations by incorporating all of the behavioural data and separating out response biases. We applied the diffusion model to data from lexical decision and recognition memory tasks and showed consistent effects, specifically a positive emotional bias in non-dysphoric subjects and even-handedness in dysphoric subjects. This pattern was not apparent with comparisons of reaction times or accuracy, consistent with previous null findings. These results suggest a relationship between dysphoria and the internal representation of emotional information.