The neural correlates of implicit and explicit self-relevant processing Lian T. Rameson a,���, Ajay B. Satpute b, Matthew D. Lieberman a a University of California, Los Angeles, USA b Columbia University, USA a b s t r a c t a r t i c l e i n f o Article history: Received 11 September 2009 Revised 20 November 2009 Accepted 22 December 2009 Available online 4 January 2010 Keywords: Implicit self-processing Explicit self-processing fMRI Social cognitive neuroscience Self-relevance Neuroimaging investigations of self-processing have generally focused on the neural correlates of explicit self-reflection. However, very little is known about the neural basis of implicit self-related processes. We utilized the concept of self-schemas to construct a two-task fMRI study that elicited both implicit and explicit self-relevant processes. The sample consisted of 18 participants who were schematic for either athletics or science. In the implicit self-relevance task, individuals made non-self-relevant judgments about affectively neutral scientific and athletic images. In the explicit self-reference task, participants judged the self- descriptiveness of adjectives related to athletics or science. Implicit and explicit processing of self-relevant (schematic) material elicited activity in many of the same regions, including medial prefrontal cortex, posterior cingulate/precuneus, ventromedial prefrontal cortex, subgenual anterior cingulate, amygdala, and ventral striatum. We suggest that processing self-related material recruits similar neural networks regardless of whether the self-relevance is made explicit or not. �� 2009 Elsevier Inc. All rights reserved. Within the past decade, investigations of the neural basis of self- knowledge have yielded a remarkably consistent body of evidence. In particular, an assortment of neuroimaging studies has convincingly demonstrated that cortical midline structures are implicated in self- referential thought and self-reflection (Lieberman, in press Northoff et al., 2006). The medial surface of the prefrontal cortex and precuneus/posterior cingulate cortex (precuneusPCC) have been shown to be engaged during tasks which involve relatively unstruc- tured self-reflection (D'Argembeau et al., 2005 Kjaer, Nowak, and Lou, 2002), as well as tasks which require making specific judgments about one's own traits compared to judgments of others or semantic judgments (Craik et al., 1999 Gusnard et al., 2001 Heatherton et al., 2006 Johnson et al., 2002 Kelley et al., 2002 Moran et al., 2006 Zysset et al., 2002). A recent review (Lieberman, in press) identified the medial prefrontal cortex (MPFC, Brodmann's area [BA] 10) as a particularly significant region for processing self-related information, as 94% of the self-processing studies reviewed evinced activation in this area. PrecuneusPCC and dorsomedial prefrontal cortex (dMPFC) were the next most frequently observed regions at 63% and 53%, respectively. These investigations all utilized paradigms that involved explicit forms of self-reflection, and commonly asked participants to judge whether a broad variety of adjectives were self-descriptive. However, the extent to which such paradigms capture the kinds of self-related processing that occurs in everyday life remains unclear, because it is relatively unusual that one is directly asked about one's personality or abilities. Rather, self-reflection of the variety that these experiments instantiate probably takes place relatively infrequently ��� for example, in therapy, writing a resume, or becoming acquainted with a new individual. As noted by Devos and Banaji (2003), it has been commonly assumed that studying the self primarily involves measuring reflective self-consciousness, with knowable and accessi- ble goals, motivations, and cognitions. However, studies of ���uncon- scious modes of thinking and feeling, when applied to self and identity processes, question these assumptions, and they do so based on the discovery of mental acts that are fully meaningful and lawful but that appear to arise without introspective access or deliberative thought��� (p. 153). Much of the contemporary research on the self has relied less on explicit evaluations of the self and instead examined aspects of the implicit self-concept, which has been found to have profound effects on life decisions, such as career choice (Pelham et al., 2005). In keeping with this behavioral literature, we broadly define implicit self-processing as associations about the self that are relatively automatic and occur below the level of conscious awareness. These forms of implicit self-knowledge and self-evaluation may better reflect the operation of self-processes in everyday life (Bargh and Barndollar, 1996 Fitzsimons and Bargh, 2004). For example, when flipping through television channels, one usually does not explicitly ask oneself: ���Am I a funny person who likes comedies or a serious person who prefers documentaries?��� Instead, one's implicit self- knowledge guides one's behavior to make an appropriate selection in a way that is adaptive, automatic and below the level of awareness. To our knowledge, only one neuroimaging study has attempted to examine implicit self-processing (Moran et al., 2009). In this study, NeuroImage 50 (2010) 701���708 ��� Corresponding author. Department of Psychology, 1285 Franz Hall, University of California Los Angeles, Los Angeles, CA 90095-1563, USA. E-mail address: lrameson@gmail.com (L.T. Rameson). 1053-8119/$ ��� see front matter �� 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.neuroimage.2009.12.098 Contents lists available at ScienceDirect NeuroImage journal homepage: www.elsevier.com/locate/ynimg

participants completed a color oddball task in which the experi- menters manipulated whether text stimuli were self-related or not. The cover story informed participants that self-related stimuli (hometown, initials, parent's name, etc.) were included to make the task more interesting. Compared to control stimuli, self-related information activated MPFC, dMPFC and posterior cingulate, areas previously associated with explicit self-processing. However, al- though this task was intended to solely elicit implicit processing, it is possible that the nature of the stimuli employed in the study may have also unintentionally instigated explicit self-processes. Most prominently, the fact that the stimulus materials were directly and obviously related to the self may have encouraged spontaneous explicit self-reference regardless of instructions. For example, seeing the name of one's pet might cause an explicitly self-referential reaction such as, ���Hey ��� that's my dog!��� which might also lead to further explicit self-related processes (���I wonder when I will be done with this so I can take Fido for a walk���). While this study represents a commendable first step towards isolating the neural regions associ- ated with implicit self-processing, it seems clear that additional research utilizing novel methodologies is needed to confirm and expand these initial findings. The current study attempts to identify the neural regions involved in implicit self-processing while avoiding some of the limitations of previous work. To construct such a task, we drew upon the behavioral literature examining self-schemas (Markus and Wurf, 1987). Possessing a self-schema for a particular domain is effectively equivalent to being highly identified with the domain (Markus, 1977). Previous neuroimaging research has already identified regions associated with explicit self-schematic processing (e.g., actors responding to acting words), including ventromedial prefrontal cortex (vMPFC, BA 11), ventral striatum, amygdala, and precuneusPCC (Lieberman et al., 2004). However, employing self- schematic materials also provides an ideal means of inducing implicit self-processing by exposing participants to pictorial stimuli that are inherently self-relevant while avoiding explicit forms of self-refer- ence. Thus, the current study seeks to expand upon the previous investigation through the inclusion of an additional task that specifically targets implicit self-schematic processes through such presentations. For this study, we recruited individuals who were self-schematic for either athletics or science, but not both. We chose two domains in order to increase generalizability of the results and to provide a neutral control condition. The study consisted of two tasks. The im- plicit self-relevance task was designed to instantiate implicit self- processing through exposure to self-relevant (schematic) material. In this task, participants viewed a series of affectively neutral images related to science and athletics and made a non self-referential judgment about each (���is there a person in the image?���). The explicit self-reference task was designed to isolate the neural correlates of explicit self-reflection associated with schematic processing. In this task, participants judged the self-descriptiveness of a series of positive and negative adjectives related to science and athletics. We were specifically interested in testing whether the same neural structures that were involved in the explicit processing of schematic content would be recruited during implicit processing of schematic material. In other words, does the implicit processing of self- schematic material activate the network previously shown to be associated with self-schematic processing, more traditional self- reflection regions, or neither? Method Participants We recruited 18 healthy, right-handed, non-claustrophobic UCLA undergraduate students from the Psychology participant pool, classroom announcements, and campus fliers. Individuals are consid- ered self-schematic for a particular domain if they believe themselves to be extreme on a dimension that is important to their self-concept (Markus, 1977). Therefore, to assess schematicity, potential partici- pants rated the adjectives ���scientific��� and ���athletic��� on their descriptiveness and importance to self-concept on a scale from 1 (not at all) to 11 (very much). The two ratings for each adjective were averaged to create independent indices of athletic and scientific schematicity and individuals who scored above 8 on one domain and below 4 on the other were eligible to participate. Participants were given either course credit or $25 as compensation. This study was approved by and conducted in compliance with UCLA's institutional review board. 1 participant was excluded due to excessive head motion during scanning which resulted in a final fMRI dataset of 17 (4 male, 9 athletes, mean age=19.5). Equipment failure resulted in the loss of behavioral data for another participant, therefore behavioral analyses were conducted on 16 individuals (4 male, 9 athletes, mean age=19.4). Implicit self-relevance task Procedure In this event-related task, participants viewed a series of 88 affectively neutral athletic and scientific images for 3 s each and judged whether each image contained people or not. This instruction was intended to prevent explicit self-reference and ensure equal attendance to all images. Null events of the same duration were included in order to obtain a measure of baseline neural activity as well as enable estimation of the hemodynamic response. The stimuli were presented in two runs of 198 s and presentation order was determined using OptimizeDesign (Wager and Nichols, 2003). The implicit task was run first in order to avoid any potential self-related priming from the explicit schematic self-reflection task. Materials Images were chosen that were representative of their respective categories, low in arousal, and of neutral valence. Half of the images from each category depicted people and half depicted inanimate objects. A wide range of exemplars was included in order to make sustained explicit self-reference implausible, because participants were unlikely to have a range of experience equal to the breadth of the material. For example, athletic images included depictions of basketball, football, lacrosse, tennis, track and field, swimming, baseball, hockey, water polo, and weight lifting. Scientific images encompassed the fields of biological science, chemistry, mathematics, physical science, earth science, computer science, and social science. See the Methodological details portion of the online Supplementary materials for further information. Explicit self-reflection task Procedure In this mixed-design task, participants viewed 40 scientific and 40 athletic adjectives and judged whether each adjective was self- descriptive by responding ���me��� or ���not me��� as quickly as possible. Half of the adjectives within each domain were positively related to the domain (e.g., ���sporty��� for athletics), and half were negatively related (e.g., ���flabby���). Adjectives were presented for 3 s each within alternating domain-specific blocks of 30 s in length. Each block was separated by 18 s of rest. Forty null events of 3 s in duration were inserted within blocks to allow for separate estimation of the hemodynamic response to the four conditions (positive athletic, negative athletic, positive scientific, negative scientific). Stimuli were presented in two runs of 288 s each, comprised of 6 blocks of trials and 6 rest periods. Trial order was determined using OptimizeDesign 702 L.T. Rameson et al. / NeuroImage 50 (2010) 701���708