Does Unconscious Information Improve Perceptual Decision-making?

Abstract

Contrary to the widespread belief that careful conscious thought leads to good decisions, recent psychophysical studies have argued that unconscious information can improve conscious decisions. However, these studies likely failed to manipulate conscious awareness in their experiments. To address this issue, we used a new technique called continuous flash suppression (CFS), which provides a powerful method to reliably manipulate conscious awareness in visual perception. This technique was combined with a simple perceptual decision paradigm in the same experimental protocol as the recent psychophysical studies. This protocol enabled us to investigate whether unconscious information can alter conscious perceptual decisions. Participants were asked to decide the direction of a coherent random-dot motion stimulus and then to rate the confidence of the random-dot motion direction judgments. We found that unconscious motion information was not integrated with conscious decision-related motion information to increase both decision accuracy and confidence when the motion stimuli were presented for the first few hundred milliseconds with strong perceptual suppression induced by the CFS stimuli. These results suggest that unconscious information does not improve conscious decisions.