The neural substrates of person perception: Spontaneous use of financial and moral status knowledge

Abstract

The current study examines the effect of status information on the neural substrates of person perception. In an event-related fMRI experiment, participants were presented with photographs of faces preceded with information denoting either: low or high financial status (e.g., “earns $25,000” or “earns $350,000”), or low or high moral status (e.g., “is a tobacco executive” or “does cancer research”). Participants were asked to form an impression of the targets, but were not instructed to explicitly evaluate their social status. Building on previous brain-imaging investigations, regions of interest analyses were performed for brain regions expected to support either cognitive (i.e., intraparietal sulcus) or emotional (i.e., ventromedial prefrontal cortex) components of social status perception. Activation of the intraparietal sulcus was found to be sensitive to the financial status of individuals while activation of the ventromedial prefrontal cortex was sensitive to the moral status of individuals. The implications of these results towards uncovering the neural substrates of status perception and, more broadly, the extended network of brain regions involved in person perception are discussed.

Introduction

Our ability to successfully interact with others depends on a variety of social cognitive skills, which include various person perception processes. Much progress has been made identifying the neural substrates involved in perceiving key social dimensions of others. A network of brain regions, including the fusiform cortex, superior temporal sulcus, amygdala and nucleus accumbens, appear to be involved in processing perceptually identifiable social dimensions of unfamiliar individuals, such as their race, gender, emotional expression, attractiveness, and perceived likability or dominance (Adolphs, 2002, Cloutier and Macrae, 2008, Fiske, 2010, Freeman et al., 2009, Heberlein et al., 2008, Phelps et al., 2000, Todorov et al., 2007). Additionally, compared to unfamiliar individuals, well-known individuals often elicit greater activation in brain regions believed to support social cognition, particularly the medial prefrontal cortex (MPFC) (Decety et al., 2012, Gobbini et al., 2004, Gobbini and Haxby, 2007). This increased activation in MPFC may index the evaluation of a social target or availability of person-knowledge about a social target (Decety et al., 2012, Gobbini et al., 2004, Kringelbach and Rolls, 2004, Whalen et al., 1998).

Despite such advances towards uncovering the neural substrates of person perception, little is known about the social cognitive processes involved in the perception of social status in humans (Engell et al., 2007, Marsh et al., 2009). Nonetheless, a growing number of brain-imaging investigations have attempted to identify the impact of a target’s social status on the neural substrates of its perception (Cloutier et al., 2008, Karafin et al., 2004, Zaki et al., 2011, Magee and Galinsky, 2008, Zink et al., 2008b). In these studies, however, it is often difficult to isolate the social dimensions from which status is inferred or to distinguish between the impact of social status and other potentially related constructs (e.g., facial cues of dominance). In contrast to the dominance hierarchies observed in many non-human primate species (Cheyney & Seyfarth, 2007), the status of humans is often inferred from multiple social dimensions (for example socioeconomic status is composed of distinct social dimensions such as education and financial status). Furthermore, hierarchies within different social groups (e.g., members of a country club versus volunteers in a charitable organization) may be based on a range of distinct characteristics describing its members. Indeed, inasmuch as members of a group sufficiently value a status characteristic, the social dimension in question can be the basis of a hierarchical social structure (Engell et al., 2007, Marsh et al., 2009).

Assessing the social status of others is a vital aspect of person perception and is ubiquitous in guiding social interactions in numerous environments (Magee & Galinsky, 2008). Not only do social status cues provide relevant information about people we encounter, they also serve as indicators of our own position within a given hierarchy and may often be a source of personal motivation (Hogg, 2001, Jenkins et al., 2008, Marsh et al., 2009). Accordingly, perceivers should be motivated to spontaneously infer the social status of conspecifics when relevant knowledge is available.

Previous brain-imaging studies have identified brain regions responsive to information relevant to the social status of targets (Cheyney and Seyfarth, 2007, Cloutier et al., 2008, Ly et al., 2011, Magee and Galinsky, 2008, Zink et al., 2008b). The parietal cortex, particularly the intraparietal sulcus (IPS), has been recruited when people explicitly compare the social status of two individuals (Chiao et al., 2009). This region has been implicated in both the evaluation of social distance and in the performance of non-social numerical comparison (Yamakawa, Kanai, Matsumura, & Naito, 2009). Such findings suggest that the IPS may be involved in the cognitive assessment of hierarchical structures (e.g., mapping the relative positions of individuals within a hierarchy). In contrast, the ventral medial prefrontal cortex (VMPFC) might be involved in the affective evaluation of social targets as a function of their social status. This region has been suggested to be sensitive to the value of social targets during person perception (Karafin et al., 2004), and appears to underlie the affective component of moral evaluations (Adolphs, 2009, Anderson et al., 1999, Cloutier et al., 2011, Greene, 2007, Koenigs et al., 2007, Moll et al., 2002, Moll and de Oliveira-Souza, 2007). Therefore, it may be hypothesized that the IPS is engaged in assessing relative positions of social status within a hierarchy, and the VMPFC is engaged in the affective evaluation of social status.

The current study attempted to identify the neural responses to social targets varying on two distinct social status dimensions (i.e., financial and moral status). In an event-related fMRI design, participants were presented with photographs of unknown individuals preceded by information describing either their financial (i.e., based on income) or moral (i.e., based on professional occupation) status. Of particular interest was the activation in brain regions hypothesized to either: (1) support the cognitive assessment of hierarchical standing (e.g., IPS); or (2) support the affective evaluation of social targets based on their social status (e.g., VMPFC).