The neural basis of intuitive and counterintuitive moral judgment

Abstract

Neuroimaging studies on moral decision-making have thus far largely focused on differences between moral judgments with opposing utilitarian (well-being maximizing) and deontological (duty-based) content. However, these studies have investigated moral dilemmas involving extreme situations, and did not control for two distinct dimensions of moral judgment: whether or not it is intuitive (immediately compelling to most people) and whether it is utilitarian or deontological in content. By contrasting dilemmas where utilitarian judgments are counterintuitive with dilemmas in which they are intuitive, we were able to use functional magnetic resonance imaging to identify the neural correlates of intuitive and counterintuitive judgments across a range of moral situations. Irrespective of content (utilitarian/deontological), counterintuitive moral judgments were associated with greater difficulty and with activation in the rostral anterior cingulate cortex, suggesting that such judgments may involve emotional conflict; intuitive judgments were linked to activation in the visual and premotor cortex. In addition, we obtained evidence that neural differences in moral judgment in such dilemmas are largely due to whether they are intuitive and not, as previously assumed, to differences between utilitarian and deontological judgments. Our findings therefore do not support theories that have generally associated utilitarian and deontological judgments with distinct neural systems.

Fig. 1

Overview of fMRI data analysis. (A) Brain responses to utilitarian moral judgments (UI_U and DI_U) were compared to responses to deontological moral judgments (UI_D and DI_D). (B) Comparison of intuitive (UI_U and DI_D) vs counterintuitive moral judgments (UI_D and DI_U). (C) Comparison of moral judgments in DI dilemmas (DI_D and DI_U) vs judgments in UI dilemmas (UI_U and UI_D). (D) Comparison of single conditions. In analysis D, utilitarian judgments in DI dilemmas were compared to (i) deontological judgments in DI dilemmas (DI_U vs DI_D; analysis D), (ii) utilitarian judgments in UI dilemmas (DI_U vs UI_U; analysis D1) and (iii) deontological judgments in UI dilemmas (DI_U vs UI_D; analysis D2). Analysis E (deontological judgments in DI dilemmas) follows a parallel form. The dilemma that is substracted is marked in green, the dilemma that is subtracted from is marked in red.

Fig. 2

Behavioral data. (A) Relative number of utilitarian and non-utilitarian judgments (averaged across subjects) in DI dilemmas where the deontological option was considered intuitive and UI dilemmas where the utilitarian option was considered intuitive. Participants chose the intuitive option significantly more often than the counterintuitive option in both types of dilemmas (P ≤ 0.001). (B) Difficulty rating for utilitarian and deontological judgments in DI and UI dilemmas averaged across subjects. In both types of dilemmas, counterintuitive judgments were rated as more difficult compared to intuitive judgments (P < 0.05). (C) Response times for utilitarian and non-utilitarian judgments in DI and UI dilemmas averaged across subjects. Significantly longer response times were found for DI than for UI dilemmas but not for counterintuitive compared to intuitive judgments. Error bars show standard errors.

Fig. 3

Comparison of brain responses to intuitive and counterintuitive moral judgments. (A) Intuitive moral judgments were associated with increased activation in the visual, premotor and orbitofrontal cortex and the temporal lobe. (B) During counterintuitive moral judgments, increased activation was observed in the dorsal and rostral ACC, SII, insula, VLPFC and OFC.

Fig. 4

Comparison of brain responses to deontological and utilitarian moral judgments. Deontological moral judgments led to increased activation in the PCC and the right TPJ. No significant activation was found for the comparison ‘utilitarian > deontological moral judgments’.

Fig. 5

Comparison of brain responses to moral judgments in DI and UI dilemmas. During moral judgments in DI dilemmas, increased activation was found in the right VLPFC and DLPFC, PCC, right TPJ. No significant activation was found for the comparison ‘UI dilemmas > DI dilemmas’.

Fig. 6

Analysis of the role of intuitiveness and content in judgments of DI dilemmas. (A) Analysis D (DI_U > DI_D): compared to deontological moral judgments in DI dilemmas, utilitarian judgments were associated with increased activation in the right insula, VLPFC, SII, left OFC, rACC and visual cortex. (D1) Of these regions, only the visual cortex was also activated in the comparison of DI_U with deontological judgments in UI dilemmas (indicated by green dots). (D2) In contrast, overlap with the results of analysis D was found in the VLPFC, rACC, SII and visual cortex when DI_U was compared with utilitarian judgments in UI dilemmas (indicated by red dots). Analysis E (DI_D > DI_U): compared to utilitarian moral judgments in DI dilemmas, deontological judgments were associated with increased activation in the visual cortex, bilateral temporal lobe, left premotor and right orbitofrontal cortex. (E1) Of these regions, none showed increased activation when DI_D was compared with utilitarian judgments in UI dilemmas (indicated by green dots). (E2) In contrast, overlap was found in the visual, premotor and orbitofrontal cortex when DI_D was compared with deontological judgments in UI dilemmas (indicated by red dots).