Lassiter, G. D., Lindberg, M. J., Gonzàlez-Vallejo, C., Bellezza, F. & Phillips, N. D. (2009). The deliberation-without-attention effect: Evidence for an artifactual interpretation. Psychological Science, 20(6), 671–675. 

Abstract:  Proponents of unconscious-thought theory assert that letting the unconscious “mull it over” can enhance decisions. In a series of recent studies, researchers demonstrated that participants whose attention was focused on solving a complex problem (i.e., those using conscious thought) made poorer choices, decisions, and judgments than participants whose attention was distracted from the problem (i.e., those purportedly using unconscious thought). We argue that this finding, rather than establishing the existence of a deliberation-without-attention effect, is explained more compellingly in terms of the well-established distinction between on-line and memory-based judgments. In Experiment 1, we reversed the recent finding by simply changing participants' on-line processing goal from impression formation to memorization. Experiment 2 provided a replication and further established that some cognitive effort appears necessary to produce both the original pattern of results and its reversal, suggesting that such judgments are ultimately a product of conscious, rather than unconscious, thinking.

References: Download PDF