Thinking in Patterns: using multi-voxel pattern analyses to find neural correlates of moral judgment in neurotypical and ASD populations

Thinking in Patterns: using multi-voxel pattern analyses to find neural correlates of moral judgment in neurotypical and ASD populations Jorie Koster-Hale 1 , James Dungan 2 , Rebecca Saxe 1 , Liane Young 2 1 Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge MA 02139 2 D epartment of Psychology, Boston College, Chestnut Hill, MA 02467 Abstract intentions to forgive accidents (Grant et al, 2005). In a recent study, Moran et al. (2011) found that high-functioning adults with ASD show the same pattern, delivering less forgiveness and more blame for accidents than neurotypical (NT) adults. These findings suggest that the RTPJ should encode the difference between accidental and intentional harm. Puzzlingly, however, we find that the average mean signal – a standard way of measuring neural involvement in a task – in RTPJ and the other theory of mind regions is not different for intentional versus accidental harmful actions in NT participants. One possibility is that this key dimension can be detected, not in the magnitude of response across a brain region, but in the pattern of responses across voxels. A complementary approach to traditional neuroimaging analyses (which rely on average response magnitude) is to look at the pattern of activity across voxels within a region, using a technique called multi-voxel pattern analysis. If a different tasks, stimulus categories, or stimulus features are processed by (partially) different subpopulations of neurons within a brain region, the difference may not be detectable in the region’s average response, but may nevertheless produce systematic and distinct patterns of activity across neighboring voxels within the region (Normal et al, 2006; Haynes et al, 2006; Kriegeskorte & Bandetti, 2007). A key advantage of this technique is that these patterns can be used to ‘decode’ information from the neural response not otherwise detectable in the overall magnitude (e.g., object category in ventral temporal regions, Haxby et al 2001). Thus MVPA can reveal how stimulus categories are processed within a functional region (Peelen et al, 2006; Haynes & Rees, 2006). Given the importance of intentions for moral judgments of accidental and intentional harms, we predicted that one or more brain regions in the ToM network would explicitly encode this feature of others’ mental states, in neurotypical (NT) adults. That is, we predicted that (i) while participants read about a wide range of harmful acts, we would be able to decode whether the described harm was intentional or accidental based on the spatial pattern of activity within ToM brain regions. We tested this prediction in three experiments. We also investigated (ii) whether the robustness of the spatial pattern information within individuals would predict those individuals’ moral judgments, and (iii) whether high- functioning adults with ASD, who make atypical moral judgments of accidental harms, would show correspondingly atypical patterns of neural activity. Intentional harms are typically judged to be less forgivable than accidental harms. This difference depends on mental state reasoning (i.e., reasoning about beliefs and intentions), supported by a group of brain regions, the ‘theory of mind’ network. Prior research has found that (i) interfering with activity in this network can shift moral judgments away from reliance on mental state information, and (ii) high-functioning individuals with Autism Spectrum Disorder (ASD) rely significantly less on mental state information to make moral judgments than matched neurotypical (NT) participants. Across three experiments, we find using multi-voxel pattern analysis (MVPA) that, in NT adults, (i) one key region of the ToM network, the RTPJ, shows reliable and distinct spatial patterns of responses across voxels for intentional versus accidental harms, and (ii) individual differences in this neural pattern predict individual differences in moral judgment. By contrast, (iii) in ASD adults, the difference between intentional and accidental harms is not encoded in the voxel- wise pattern in the RTPJ or any other region, and (iv) higher symptom severity scores are predictive of diminished pattern discriminability. We conclude that MVPA can detect features of mental state representations and that these features are behaviorally and clinically relevant. Keywords: morality, harms, theory of mind, autism, fMRI, multivoxel pattern analysis (MVPA) Introduction Intentional harms are usually judged to be morally worse than the same harms caused by accident (Cushman, 2008; Knobe, 2005; Malle & Knobe, 1997; Piaget, 1965; Singer et al, 2004; Young & Saxe, 2011). The capacity to distinguish between intentional and accidental harms depends on the capacity to represent another person’s mental states, a cognitive function associated with a specific and selective group of brain regions (the ‘theory of mind network’). Prior research has revealed that moral judgments of harmful actions depend on one region in particular, the right temporo-parietal junction (RTPJ). For example, individual differences in moral judgments of accidental harms are correlated with RTPJ activity (Young & Saxe, 2009), and disrupting RTPJ activity interferes with these judgments (Young et al, 2010). Recent evidence suggests that moral judgments may provide a sensitive measure of enduring impairments in ToM in high-functioning individuals with Autism Spectrum Disorders (ASD). Children with ASD are disproportionately impaired on tasks that require them to consider the beliefs and intentions of other people (Peterson et al, 2005; Baron-Cohen, 1995). Although children with ASD distinguish between moral and conventional transgressions (Blair et al, 1996), and between good actions and bad actions (Leslie et al, 2006), they are delayed in using information about innocent Methods Participants Experiment 1: Sixteen right-handed members of the MIT community (aged 18-50, 7 women). Experiment 2: Eighteen