Are difficult decisions best made after a momentary diversion of thought? Previous research addressing this important question has yielded dozens of experiments in which participants were asked to choose the best of several options (e.g., cars or apartments) either after conscious deliberation, or after a momentary diversion of thought induced by an unrelated task. The results of these studies were mixed. Some found that participants who had first performed the unrelated task were more likely to choose the best option, whereas others found no evidence for this so-called unconscious thought advantage (UTA). The current study examined two accounts of this inconsistency in previous findings. According to the reliability account, the UTA does not exist and previous reports of this effect concern nothing but spurious effects obtained with an unreliable paradigm. In contrast, the moderator account proposes that the UTA is a real effect that occurs only when certain conditions are met in the choice task. To test these accounts, we conducted a meta-analysis and a large-scale replication study (N = 399) that met the conditions deemed optimal for replicating the UTA. Consistent with the reliability account, the large-scale replication study yielded no evidence for the UTA, and the meta-analysis showed that previous reports of the UTA were confined to underpowered studies that used relatively small sample sizes. Furthermore, the results of the large-scale study also dispelled the recent suggestion that the UTA might be gender-specific. Accordingly, we conclude that there exists no reliable support for the claim that a momentary diversion of thought leads to better decision making than a period of deliberation.

According to the deliberation without attention (DWA) hypothesis, people facing a difficult choice will make a better decision after a period of distraction than after an equally long period of conscious deliberation, an effect referred to as the unconscious thought advantage (UTA). The status of the DWA hypothesis is controversial, as many studies have tried but failed to replicate the UTA. Here, we report a series of experiments that sought to identify the conditions under which the UTA can be replicated. Our starting point was a recent meta-analysis that identified the conditions under which the UTA was strongest in previous studies. Using a within-subjects design and a task that met each of these conditions, we failed to replicate the UTA. Based on closer inspection of previous methods and findings, we then examined some additional factors that could be important for replicating the UTA, including mental fatigue and choice complexity. This was to no avail, as the results revealed only a significant conscious thought advantage, when choice complexity was increased relative to the first experiment. We subsequently conducted exploratory analyses on the data across experiments and found that male subjects showed a significant conscious thought advantage while female subjects showed a trend towards an UTA. Taken together, our results suggest that replication of the UTA may depend more on characteristics of the sample than on the characteristics of the task, and they suggest that gender could be a source of variance in the outcomes of previous studies using a between-subjects design.