Knowledge of explicit social and moral norms was evaluated using 15 items from the Moral Behaviour Scale [16], to which the subjects responded by choosing “not wrong”, “mildly wrong”, “moderately wrong” or “severely wrong”, on a 4-point rating scale.

<p>Knowledge of explicit social and moral norms was evaluated using 15 items from the Moral Behaviour Scale <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039882#pone.0039882-McGuire1" target="_blank">[16]</a>, to which the subjects responded by choosing “not wrong”, “mildly wrong”, “moderately wrong” or “severely wrong”, on a 4-point rating scale.</p

Demographic and clinical data of the 39 subjects participating in the study, with values in parenthesis referring to 1 standard deviation.

<p> <i>1) MADRS  =  Montgomery-Asberg Depression Rating Scale 2) AUDIT  =  Alcohol Use Disorder Identification Test 3) DUDIT  =  Drug Use Disorder Identification Test.</i></p

Moral judgment on each moral personal dilemma.

<p>The proportion of ‘yes’ responses are shown for the two groups for each of the 21 moral personal dilemmas. The dilemma numbers are directly adapted from Koenigs et al. (2007) and sorted according to increasing proportion of ‘yes’ responses, i.e. endorsing the proposed utilitarian action, by the healthy controls. Dilemmas labelled 1–8 and 9–21 are low-conflict type and high-conflict type respectively. Alcohol dependent patients responded equally or more utilitarian than healthy controls for all personal moral dilemmas except one, and the difference in response was more pronounced for the high-conflict dilemmas (P = 0.036) compared to low-conflict dilemmas (P = 0.063).</p

Moral judgments of three classes of dilemmas: non-moral, impersonal moral and personal moral dilemmas.

<p>The proportion of ‘yes’ responses are shown for the two groups. Alcohol dependent patients were more likely than healthy controls to respond ‘yes’, i.e. endorsing the proposed utilitarian action, when faced with moral personal dilemmas (P = 0.024). However, no such difference was found for non-moral (P = 0.377) or impersonal moral dilemmas (P = 0.161). Error bars indicate 95% confidence intervals.</p