NoteAlexithymia decreases altruism in real social decisions
Introduction
As a social species, humans are fundamentally motivated by the need for interindividual bonding and social attachment (Fehr and Fischbacher, 2003). And yet, there a number of clinical populations—including those with anti-social personality disorder (Hare et al., 1991), psychopaths (Blair, 2001), and frontal lobe patients (Damasio, 1994)—who consistently express anti-social tendencies (Anderson et al., 1999; Blair, 1995; Raine and Yang, 2006). The question of why these individuals routinely behave in ways that oppose the deep-seated evolutionary propensity to partake in positive social bonding has long intrigued psychologists.
Effective emotional processing is thought to be critical for successful social behaviour (Blair, 2007). This is supported by extensive research cataloguing the putative relationship between emotion regulation and prosocial decision-making (Eisenberg, 2000). Clinical populations who exhibit a reduced ability to respond to the observation of distress in others (Blair et al., 2006) have provided explicit evidence that emotional responsivity is integral to how humans navigate interpersonal situations. Alexithymia—a personality construct characterized by the sub-clinical inability to identify and describe emotions in the self (Sifneos, 1973)—is prevalent in approximately 10% of the general population and is known to be comorbid with a number of psychiatric conditions (Taylor et al., 1999). The core characteristics of alexithymia are marked dysfunction in emotional awareness (Sifneos, 1973), social attachment (Vanheule et al., 2007), and interpersonal relating (Berthoz et al., 2002). By extension, alexithymics also have difficulty in distinguishing and appreciating the emotions of others (Taylor et al., 1997), and this is thought to lead to unempathic and ineffective emotional responding (Bernhardt and Singer, 2012; Taylor et al., 1999).
Recent neuroimaging data provides convergent evidence that these symptoms are likely due to underlying dysfunction in brain regions critical for processing social and affective information (Aleman, 2005), including the temporoparietal junction (TPJ), dorsal anterior cingulate cortex (dACC) and anterior insula (AI) (Berthoz et al., 2002; Bird et al., 2010; Frewen et al., 2008; Moriguchi et al., 2007; Silani et al., 2008). These findings fit with the general consensus that the AI and dACC, which are key regions in the pain matrix, encode for the shared experience of distress (Singer et al., 2004). A broader perspective illustrates that other clinical populations exhibit similar deficits in emotional processing, but present with dysfunction in different brain regions. For example, when presented with highly aversive and emotionally arousing moral dilemmas, ventromedial prefrontal cortex (vmPFC) lesion patients make more rational, utilitarian judgements than healthy controls (Koenigs et al., 2007). One explanation for this finding is that vmPFC patients are unable to harness the requisite emotional sensitivity to aversive stimuli, and thus make more utilitarian decisions because they lack internal markers of emotionally aversive states. Recent neuroimaging has further confirmed that atypical functioning in the vmPFC can lead to aberrant empathic responding (Blair, 2008), which may be a result of an inability to express distress to threatening and aversive stimuli (Blair et al., 1997). Accordingly, in order to understand and clarify the effects of emotional deficits on the propensity for prosocial behaviour, we examined whether individuals high in the alexithymia construct display differential patterns of motivated altruistic choice—and if so, whether these are underpinned by discrete neural signatures.
Using functional resonance imaging (fMRI) and a Pain versus Gain (PvG) task (FeldmanHall et al., 2012) that operationalizes the choice between personal advantage and another's welfare, we investigated the relationship between alexithymia, state distress (Zhou et al., 2003), and altruistic action. In the PvG task, subjects were required to make a choice between maximizing their own financial self-benefit versus ensuring the physical welfare of another. We reasoned that individuals high in alexithymia would have difficulties in identifying and meaningfully registering another's distress (Koven, 2011)—and that this would be reflected by decreased activation in brain areas associated with processing the ability to share the emotional states of others, namely the TPJ (which is thought to support our capacity for theory of mind) (Young et al., 2007), and the AI [which is considered to map subjective feeling states in both the self and other (Singer and Lamm, 2009)]. We further hypothesized that evidence of a diminished distress response would result in more self-serving choices, and thus more anti-social behaviour (i.e., financial gain at the expense of another's pain in the PvG task). If this were indeed the case, we reasoned that brain regions key for processing emotional responsivity—especially the vmPFC—would be relatively deactivated during such self-serving behavioural patterns.
Section snippets
Subjects
Fifteen subjects (Deciders: six males, age 23.2, SD ± 2.8) made decisions about increasing their financial gain at the expense of another's physical welfare while undergoing scanning. Subjects were recruited through the Cambridge panel of volunteers and were not pre-selected based on their alexithymia scores. Following completion of the PvG task, subjects also completed the Toronto Alexithymia Scale (TAS-20) (Bagby et al., 1994). In line with the TAS-20, subjects who scored ≤51 were categorized
Results
Behavioural results revealed that increasing alexithymia scores correlated with the delivery of higher levels of shock and more money kept (r = .65, p = .005, Pearson correlation 1 tailed), illustrating that subjects prioritized self-benefit over the Receiver's welfare (Fig. 1a). Analysis of the brain imaging data for the Video event (visual feedback of the shock being administered, parametrically weighted to the chosen shock/money kept) allowed us to explore whether individuals high in
Discussion
Evidence of decreasing distress levels suggests that the prototypical emotional blunting seen in alexithymia can translate into diminished prosocial action and self-serving behaviour. Subjects demonstrated reduced activity in brain regions crucial for processing socio-emotional cognition. That is, increasing levels of alexithymia were associated with relative deactivation in the dACC and sgACC when viewing the consequences of their decisions. In addition, even though increasing levels of
Competing interests
The authors have declared that there are no competing interests.
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