RUNNING HEAD: The mentalizing network and high construal Involvement of the mentalizing network in social and non-social high construal

The dorsomedial prefrontal cortex (dmPFC) is consistently involved in tasks requiring the processing of mental states, and much rarer so by tasks that don’t involve mental state inferences. We hypothesized that the dmPFC might be more generally involved in high construal of stimuli, defined as the formation of concepts or ideas by omitting non-essential features of stimuli, irrespective of their social or non-social nature. In an fMRI study, we presented pictures of a person engaged in everyday activities (social stimuli) or of objects (non-social stimuli), and induced a higher level of construal by instructing participants to generate personality traits of the person or categories to which the objects belonged. This was contrasted against a lower level task where participants had to describe these same pictures visually. As predicted, we found strong involvement of the dmPFC in high construal, with substantial overlap across social and non-social stimuli, including shared activation in the vmPFC/OFC, parahippocampal, fusiform and angular gyrus, precuneus, posterior cingulate and right cerebellum. Introduction Research on the neural underpinning of social cognition has revealed a distinction between two neural networks: a mirror network, involved in processing concrete, observable behaviors, and a mentalizing network, involved in the inference of mental states or durable characteristics (see Frith & Frith, 2006; Van Overwalle & Baetens, 2009). One important region in the mentalizing network is the medial prefrontal cortex (mPFC). The mentalizing system, and the mPFC in particular, is engaged by a broad range of tasks involving emotion, the self, theory of mind and evaluation (Mitchell, 2009; Van Overwalle, 2009). As noted by Mitchell (2009), the mPFC is rarely involved (or even deactivated) in most studies on semantic memory, perception and executive functioning. A recent meta-analysis by Van Overwalle (2011) supports this notion, showing that activation of the mPFC in a broad set of reasoning studies was proportional to the amount of mentalizing content in the stimulus material, defined broadly as stimuli containing goal-directed action, beliefs, moral (in)justice, personality traits, social categories or emotions. Nevertheless, in contrast to this domain-specific view, some studies exist in which activation of the mPFC was observed in absence of such content (see below). Several authors have suggested a common process underlying the recruitment of the mPFC, whether the task requires mental state inferences or not. Mitchell (2009) suggested that the mPFC might subserve fuzzy cognition, that is, cognition that is not aiming at a maximally accurate or direct representation of reality, but is involved in representations which are “inexact, probabilistic, internally generated and subject to revision” (Mitchell, 2009, p. 249). That the mPFC is mainly recruited by social cognitive processes, might then be due to the fact that they rely more often on fuzzy representations than non-social cognitive processes. However, this explanation leaves unspecified exactly what fuzzy representations and their constituent features are. According to Legrand and Ruby (2009), the mentalizing network, including the mPFC, is involved in evaluation, defined broadly as “inferential processes and memory recall” (p. 264). As such, they assert that activity in the mentalizing system is not exclusively related to either self-related or mental state-related processes. However, this account doesn’t explain why activation of the mentalizing network is proportional to the amount of mentalizing content in the stimulus material (Van Overwalle, 2011), and particularly why the network is often not activated by tasks that do seem to require inference processes and memory recall. In the present study, we want to put forward an alternative hypothesis explaining mPFC activation more generally, both in tasks that do and do not involve the processing of mental states, particularly activation of its dorsal aspect (dmPFC; centered at the Montreal Neurological Institute coordinates 0, 50, 35 with 15 mm radius as specified by Van Overwalle & Baetens, 2009). Our hypothesis relies on construal level theory (for a review, see Trope & Liberman, 2010). Construal level theory posits that there are four dimensions of psychological distance towards a stimulus (spatial, temporal, social and hypothetical), with a positive correlation between psychological distance and construal level of the stimuli. A higher construal entails the preservation of central qualities while disregarding less essential features. To illustrate in the social domain, Trope and Liberman (2010, p. 442) claim that, “construing another person’s behavior in terms of a personality trait (a high-level construct) involves considering that person’s behavior in the past and future, in other places, and in hypothetical situations”. This process of mentally traversing psychological distance, away from the present, concrete, sensory here and now, might be a more general function subserved by the dmPFC. Several studies using tasks involving mental state inferences suggest a correlation between dmPFC activation and construal level or psychological distance. The dmPFC has been shown to become more active in personality judgment as the target is perceived to be more different from the self (social distance; Tamir & Mitchell, 2010). Higher dmPFC activation was observed when participants reflected on distal rather than proximal life goals (temporal distance; Packer & Cunningham, 2009). In an extensive meta-analysis, Van Overwalle and Baetens (2009) concluded that the dmPFC is involved in inferring enduring rather than temporary mental characteristics (e.g., personality traits versus goals), indicating a larger temporal distance in terms of construal level theory. Spunt and colleagues (2010, 2011) asked their participants to describe the how, what and why of another’s behavior. These questions prompt progressively higher levels of construal or levels of identification (LI) in terms of Action Identification Theory (Vallacher & Wegner, 1987), shifting focus from the concrete particulars of how the action is performed to its reasons, implications and effects. Spunt and colleagues (2010, 2011) found that engagement of the dmPFC progressively increased with the level of identification of an observed action (how < what < why). Results of one recent study seem less in keeping with our hypothesis: Tamir and Mitchell (2011) manipulated all four types of psychological distance in an affective forecasting task, and found a positive correlation between psychological distance and dmPFC activation only for the social dimension. Although studies reporting dmPFC involvement without any mentalizing stimulus material are rather rare (Van Overwalle, 2011), some authors have found dmPFC activation in non-social reasoning. Crucially, the need for higher CL may drive dmPFC activation in these cases too. For instance, increasing dmPFC recruitment has been found given enhanced uncertainty and unconstrained choice, employing a variety of paradigms and tasks (e.g., objective uncertainty in gambling studies, Xue et al., 2009; Stern et al., 2010; uncertainty in line length judgment, Grinband, Hirsch, & Ferrera, 2006; free choice versus rule-governed choice, (Rowe, Hughes, Eckstein, & Owen, 2008), which can be conceptualized as increasing distance on the hypothetical dimension towards the outcomes of the choices, leading to a higher CL. Furthermore, it has been shown that uncertainty by itself may lead to more global processing of stimuli (Förster, 2012). A number of studies demonstrated dmPFC involvement in non-social high construal reasoning, when tasks require the disregarding of inessential or unshared features of stimuli (e.g., judging abstract > concrete properties of animals, Goldberg et al., 2007; inductive > deductive reasoning, Goel et al., 1997; semantic distance in an analogy task, Green et al., 2010; constructing narrative or causal coherence, Ferstl & von Cramon, 2001; 2002; Siebörger, Ferstl, & von Cramon, 2007; Kranjec, Cardillo, Schmidt, Lehet, & Chatterjee, 2012; integrating premises, Fangmeier et al., 2006; sequences with taskirrelevant structure > random sequences, Turk-Browne et al., 2009). The present research In brief, we propose that the dmPFC might be crucially involved in higher construal of stimuli, independent of whether the task requires mental state inference or not. To test this hypothesis, we presented photos depicting either a woman performing routine activities (e.g., eating a salad) or manmade objects, animals and natural phenomena of neutral valence (Figure 1). Orthogonal to this, we manipulated level of construal, by asking participants to generate verbal descriptions of the visual characteristics of the image (low construal level visual) or to make abstractions of what they saw (high construal level category). More specifically, for person pictures, they were asked to generate personality traits that could possibly drive the depicted behavior. Such explicit trait inferences consistently engage the mentalizing system (e.g., Ma et al., 2011). For objects, they were asked to generate nonevaluative semantic categories by completing the sentence “This is an example of...”, a task used in the past to prime a high construal level (Wakslak & Trope, 2009). We expected that the high construal condition would activate the dmPFC more than the low construal condition, and that there would be important overlap in the dmPFC for trait inference based on person pictures and semantic categorization based on object pictures.