Conscious versus unconscious thinking in the medical domain: the deliberation-without-attention effect examined

Abstract

Previous studies have shown that with important decisions, unconscious thought has surprisingly led to better choices than conscious thought. The present study challenges this so-called ‘deliberation-without-attention effect’ in the medical domain. In a computerized study, physicians and medical students were asked, after either conscious or unconscious thought, to estimate the 5-year survival probabilities of four fictitious patients with varying medical characteristics. We assumed that experienced physicians would outperform students as a result of their superior knowledge. The central question was whether unconscious thought in this task would lead to better performance in experts or novices, in line with the deliberation-without-attention effect. We created four fictitious male 60-year-old patients, each of whom with signs and symptoms related to likely prognosis, from 12 (Complex) or 4 (Simple) categories. This manipulation resulted in objectively different life expectancies for these patients. Participants (86 experienced physicians and 57 medical students) were randomly allocated to the Simple or Complex condition. Statements were randomly presented for 8 s. Next, each participant assessed the life expectancies after either conscious or unconscious thought. As expected, experienced physicians were better in assessing life expectancies than medical students. No significant differences were found in performance between conscious and unconscious thought, nor did we detect a significant interaction between expertise level and mode of thought. In a medical decision task, unconscious thought did not lead to better performance of experienced physicians or medical students than conscious thought. Our findings do not support the deliberation-without-attention effect.

A critical review and meta-analysis of the unconscious thought effect in medical decision making

“…In summary, the experiments conducted so far to explore the UTE in clinicians’ decision making have yielded contradictory results, with the effect being observed in the original report by de Vries et al (2010) and in some (but not all) conditions of the Mamede et al (2010) and Bonke et al (2014) studies, but not in the Woolley et al (2015) study. Although this suggests that the effect might not be reliable, alternative explanations are possible.…”

“… Bonke et al (2014) explored the UTE in a medical prognosis task. Both physicians and medical students were asked to estimate the life expectancy of four hypothetical patients.…”

“…In the case of Mamede et al (2010) , the first author provided us with the descriptive statistics necessary to compute d av scores 1 . Effect sizes for Bonke et al (2014) were computed from the descriptive statistics provided in their Table 4. In the case of Woolley et al (2015) , we had access to the raw data, which allowed us to compute different effect sizes for each control condition (CT and immediate) and for two levels of difficulty (Cases 1 and 2 were coded as complex and Case 3 as simple, based on participants’ mean accuracy rates of 18, 21, and 42%, respectively).…”

“…To check that the overall results are not biased by the non-independence of data, we conducted a second meta-analysis including only independent effect sizes. A composite effect size was computed for all the related conditions in the Mamede et al (2010) and Bonke et al (2014) studies. Similarly, we computed a new effect size for Woolley et al (2015) collapsing data across the three cases (i.e., the difficulty factor) and the two control conditions (CT and immediate).…”

“…One obvious need is for careful replications of the experimental conditions that reported reliable advantages of UT over CT. A further need is for high-powered studies that explore a wider range of materials in combination with different distractor tasks. Finally, different types of deliberation conditions could be pitted against UT, e.g., self-paced (as in Woolley et al, 2015 ), fixed (as in Bonke et al, 2014 ), and proceduralized (as in Mamede et al, 2010 ). Before clinicians are formally advised to engage in UT to improve their decisions, the UTE should be explored extensively in conditions more similar to real clinical practice (see Woolley et al, 2015 ).…”