1 Moral Reasoning in Individuals with Agenesis of the Corpus Callosum

Abstract

Objective:Previous research has demonstrated that individuals with Agenesis of the Corpus Callosum (AgCC), the congenital absence of all or part of the corpus callosum, exhibit a pattern of cognitive and psychosocial deficits, even with a FSIQ in the normal range (FSIQ > 80; Brown & Paul, 2019). This includes a core deficit in their complex reasoning and novel problem-solving (Brown & Paul, 2019), with secondary deficits in capacity to imagine complex emotional/cognitive consequences of potential actions involving others (Young et al, 2019), deficits in emotionperception (Symington et at., 2010, Bridgman et al 2014), and difficulty with cognitively processing emotions within the context of social interactions (Anderson et al., 2017). This constellation of deficits is likely to also impact moral reasoning. While previous research has demonstrated differences in moral reasoning among other neuropsychological populations such as those with ventromedial prefrontal damage (Moretto et al., 2010) and frontotemporal dementia (Gleichgerrcht et al., 2011), there is no research reported regarding moral judgements in AgCC. This study employed the Moral Dilemmas Scale (Greene, 2001) to compare the moral judgements of persons with AgCC to neurotypical controls. It was predicted that individuals with AgCC would be less contextually nuanced than neurotypical controls in responding to moral dilemmas.Participants and Methods:Results consist of data derived from 57 neurotypical control participants (ages 23 to 64 years) recruited from MTurk Cloud and 19 AgCC participants (ages 23 to 77 years) with normal-range FSIQ (>80) drawn from the individuals with AgCC involved with the Human Brain and Cognition Lab at the Travis Research Institute. All participants completed an online version of the Moral Dilemmas Scale (Greene, 2001). The scale consists of 25 dilemmas, of which 11 are considered high-conflict, 7 low-conflict and 7 impersonal. Participants were instructed to read each dilemma and rate whether they found the action to be “appropriate” or not. The high-conflict dilemmas share a similar structure in which responses reflect either a utilitarian or deontological judgement.Results:“Approve” responses to each of the 3 categories of dilemma were separately tallied for each individual and subjected to a 2group ANOVA. Results revealed the control group produced a significantly higher rate of “appropriate” responses to high-conflict dilemmas than did the individuals with AgCC (F=8.17, p = .006, n2 =.113). However, no significant differences were found among the two groups for results on low (n2 = .013) and impersonal (n2 = .003) dilemmas alone. Furthermore, a X2 analysis of responses to each high conflict dilemma revealed a significant difference in 5 out of the 11 such that more persons with AgCC gave a deontological judgement.Conclusions:Results suggested that adults with AgCC respond similarly to neurotypical controls with respect to the low conflict orimpersonal dilemmas. However, with respect to high conflict dilemmas, compared to controls they tend to respond in a more deontological than utilitarian basis - that is, based on general principles without contextual nuance. These findings are consistent with the conclusion of Renteria-Vasquez et al. (2021) that persons with AgCC have difficulty imagining the wider implications of present information.