Getting to know me better: An fMRI study of intimate and superficial self-disclosure to friends during adolescence

Abstract

Adolescence is often defined as a period of social reorientation, characterized by increased engagement with, and reliance on, same-aged peers. Consistent with these shifting motivations, we hypothesized that communicating information about oneself to friends would be intrinsically valued during adolescence. We specifically examined behavioral and neural differences when sharing information of varying depth in intimacy. These questions were investigated in a sample of early adolescent girls (N = 125, ages 10.0–13.0 years) who completed a self-disclosure monetary choice task while undergoing fMRI. Behaviorally, adolescents gave up more money to share superficial self-referential information than intimate self-referential information with a (real-life) close friend. Neural analyses identified extensive engagement of regions that support social cognition and emotion regulation when engaging in intimate self-disclosure. Behavioral and neural valuation of sharing superficial information were related to individual differences in self-worth and friendship quality. Comparatively, across all levels of analyses, adolescents were less likely to share intimate information. Findings highlight both the value and costs associated with self-disclosure during this time of increased peer sensitivity.

Early adolescence is a period of social flux, when peer relationships evolve from being based around shared activities during childhood to being characterized by greater time spent in conversation with one another (Valkenburg, Sumter, & Peter, 2011). This is exemplified by adolescent use of social networking sites (Pew Research Center, 2018), but is also characteristic of “offline” behaviors (Nguyen, Bin, & Campbell, 2012). These conversations often involve sharing information about the self or self-disclosing, which is a hallmark of most human interactions. In fact 30–40% of everyday speech conveys self-referential material (Dunbar, Marriott, & Duncan, 1997). Moreover, adults will give up money for the opportunity to disclose, and engage reward centers in the brain when doing so (Tamir & Mitchell, 2012). Value for disclosure may, however, be particularly salient during the transition from childhood to adolescence – a developmental period defined by heightened motivations toward social relatedness and belonging (Pfeifer & Berkman, 2018; Somerville, 2013).

Adolescents report spending more time talking to peers than any other activity, and describe themselves as most happy when doing so (Csikszentmihalyi, Larson, & Prescott, 1977). These behavioral changes are particularly characteristic of female adolescent friendships (Davis, 2012) and occur at an earlier stage in females relative to males (Buhrmester & Prager, 1995). Increased propensity for self-disclosure is aided by the continued development of social cognitive processes during adolescence, such as advanced perspective-taking and mentalizing (Humphrey & Dumontheil, 2016), which support the ability to recognize and interpret other people’s feelings, intentions, and desires (Frith & Frith, 2012).

Depth of self-disclosure.

Self-disclosure can vary in terms of “breadth” and “depth”. Breadth refers to the range of topics that are disclosed, while depth refers to the intimacy of shared information. Social penetration theory suggests the disclosure of superficial information is important for the initiation of friendships, but it is specifically the sharing of personal and intimate information, which is often affectively charged, that supports relationship development (Altman & Taylor, 1973). Consistently, intimate disclosure has been associated with better friendship quality and perceived social support in older adolescents (i.e. college students) and adults (Li, Chen, & Popiel, 2015; Moreno et al., 2011; Zhang, 2017). However, adolescents exhibit mastery of superficial disclosure earlier than intimate disclosure (Dolgin & Kim, 1994; Jones, Dembo, & Jones, 1989), which comes online during early adolescence and continues to increase into the mid-teens (Jones & Dembo, 1989; Sharabany, 1980, 1986; Shifron, 1986). Interestingly, Rumi and Kunio (2002) found that early adolescents who had a wider circle of less intimate friendships engaged in overall more disclosures of varying depth compared to those who had a narrower circle of more intimate friends, suggesting that the ability to connect with multiple peers may serve some adaptive functions during this period. However, given that intimate information often relates to personal struggles and vulnerabilities, sharing such information may be embarrassing. Combined with increased anxiety regarding social evaluation during adolescence (van den Bos, de Rooij, Miers, Bokhorst, & Westenberg, 2014), it is possible that these potential risks may outweigh the rewards, such that intimate disclosure may be valued less than superficial disclosure during the transition from childhood to adolescence. Nevertheless individual differences may also exist during this time, such that early adolescents with closer and more supportive friendships may value sharing intimate information more than those with less supportive friendships.

At the same time, it is often hypothesized that intimate disclosure supports well-being and self-esteem by building stronger social bonds. Mutuality and reciprocity in intimate disclosures show adolescents that others respect their feelings and want their advice, leading to a validation of their self-worth (Davis, 2012; Valkenburg & Peter, 2009). Communicating with peers is also thought to reduce worries and anxieties about the physical and emotional changes adolescents are experiencing, thus leading to better adjustment (Buhrmester & Prager, 1995; Valkenburg et al., 2011). However, despite common postulations about the role of intimate disclosure in positive outcomes, research has either focused on broad definitions of intimacy or broad definitions of self-disclosure. For example, a sizable literature has examined associations between relationship intimacy or closeness and well-being, but these studies tend to define intimacy as sensitivity to one another’s needs and states (Sharabany, 1994). When focusing on self-disclosure, sharing self-referential information via internet blogging (Ko & Chen, 2009) and instant messaging (Valkenburg & Peter, 2007) has been associated with greater well-being in adolescents, but these (limited) studies have not differentiated between depths of disclosure. Only one study has specifically examined the role of intimate disclosure across any age range, finding that sharing one’s emotions with friends was positively associated with identity development and self-esteem during mid-adolescence (Papini et al., 1990). Moreover, to our knowledge, there has been no research that has directly compared differing depths of disclosure to examine whether potential effects are unique to intimate disclosure. This question is particularly important during the transition from childhood to adolescence when superficial disclosure predominates close dyadic friendships (Dolgin & Kim, 1994).

Neural correlates of self-disclosure.

Research in adults has shown that self-disclosure activates regions involved in reward processes, such as the ventral striatum [VS], ventral tegmental area [VTA], and ventromedial [vm]PFC, as well as those involved in social cognitive processes, such as the dorsomedial [dm]PFC, medial posterior parietal cortex [mpPC], and anterior temporal cortex [ATC] (Meshi et al., 2016; Tamir & Mitchell, 2012; Tamir, Zaki, & Mitchell, 2015). While a growing body of research highlights maturation of these brain regions during adolescence (for reviews, see Kilford, Garrett, & Blakemore, 2016; Silverman, Jedd, & Luciana, 2015), the neural correlates of self-disclosure in younger populations, when adolescent relevant changes in social relationships and social cognition are just emerging, remains unknown. Even more critically, prior neuroimaging research has solely focused on disclosure of superficial information. Examination of intimate disclosure during a period of increased reliance on peers for emotional support may provide valuable insight into the neurobiological underpinnings of positive socioemotional development, as well as the development and maintenance of intimate relationships more broadly.

The current study.

This study investigated the behavioral and neural phenotypes of self-disclosure to peers, and in particular the value of increasing depth or intimacy of disclosure during early adolescence. These questions were investigated in 10–13 year olds given the increasing importance of self-disclosure for the development of both social- and self-representations during this period. Participants underwent a functional neuroimaging scan while completing a modified version of the “pay-per-view” or monetary choice task (adapted from Tamir & Mitchell, 2012). Specifically, they made decisions about whether they would disclose superficial and intimate information about themselves (i.e. “share” vs. “keep private”) to a chosen close peer (ideally their best friend). Each disclosure option was associated with a monetary value, and the reward associated with self-disclosure was quantified as the amount of money that adolescents would forgo in order to share information. Alongside this behavioral index, we also examined the neural underpinnings of self-disclosure and related behavioral and neural phenotypes to the quality of peer relationships and perceptions of self-worth and social competence.

Consistent with prior research on adults, it was hypothesized that early adolescents would forgo money to share information with their friends, indicating that they value self-disclosure. We also examined whether value for disclosure of intimate and superficial information differed during early adolescence. While social penetration theory suggests that individuals would forgo more money to disclose intimate information to their close friends, we predicted that early adolescents would forgo more money to disclose superficial information given that it is the prototypic type of communication in this age range, and there may be increased concerns about the risks of sharing intimate information during this period of peer sensitivity. When considering the neural correlates of self-disclosure, it was uncertain whether intimate or superficial disclosure decisions (specifically the process of deciding whether to share information) would engage regions involved in reward (i.e. VS and VTA) to a greater extent, given inconsistencies between prior neural findings in adults and behavioral patterns in early adolescents. However, intimate disclosure decisions were hypothesized to elicit greater activation of brain regions subserving social cognition and self-referential processes (such as vmPFC, dmPFC, mpPC, ATC and temporoparietal junction [TPJ]) compared to superficial disclosure decisions. It was also hypothesized to engage regions implicated in affective reactivity and regulation (i.e. amygdala, dorsal and ventral ACC, anterior insula, lateral PFC) to a greater extent than superficial disclosure, as it involves weighing up the costs and benefits of sharing potentially distressing or embarrassing information.

Finally, we expected individual differences in early adolescents’ valuation of self-disclosure. It was hypothesized that early adolescents with better friendship quality, as well as greater perceived social competence and self-worth, would be willing to forgo more money for intimate than superficial disclosure, and also exhibit greater neural activation of reward networks while doing so. The hypotheses above, and methods below, were pre-registered and can be found at https://osf.io/vefsz. Justifications for certain methodological changes were documented in an addendum that can be found at https://osf.io/hm3xf. Pre-registration was completed prior to data analysis, but we note that data collection was completed and sample descriptives (i.e. age, pubertal stage, ethnicity and race) were known.

Method

Participants

A community sample of 174 adolescent girls, aged 10.0 to 13.0 years (mean = 11.55 years, SD = 0.81 years), were recruited from [deleted], into a longitudinal project called the [deleted] study. The majority of participants were recruited from primary and middle schools in the region, and a small subset were recruited by other methods (e.g., advertising at science fairs, Craigslist). Inclusionary criteria consisted of i) fluency in English, ii) no developmental disabilities (aside from Attention Deficit/Hyperactivity Disorders), iii) no diagnosis of psychotic disorders, iv) no MRI contraindications, v) an upper age limit of 13.0 years at entry into the study. The race and ethnicity of participants is presented in Table 1.

Table 1.

Race & ethnicity of the sample

	N	%
Race
White	135	77.6
American Indian/ Alaskan Native	1	0.6
Asian	2	1.1
Native Hawaiian/ Pacific Islander	0	0
African American	2	1.1
Multiracial	34	19.5
Hispanic Ethnicity	28	16.1

Of this larger sample, 10 elected not to participate in the MRI portion, 11 did not complete the self-disclosure fMRI task (4 of these participants only completed one out of two runs), 6 participants’ data were not collected due to technical errors, 2 participants did not complete the task correctly (ascertained by multiple random button presses on trials), and a further 20 participants failed quality control checks pertaining to motion (N = 19) or first-level modelling (N = 1; see below for further detail). The remaining 125 participants were used in these analyses. The 20 participants excluded for quality control showed small, non-significant differences from the final sample in age (t ₍₃₀₎ = 0.1, p = 0.9) and behavioral valuation of superficial (t ₍₃₀₎ = −0.8, p = 0.4) and intimate (t ₍₃₀₎ = 0.04, p = 1.0) disclosure. Refer to Table S1 for descriptives of these two samples.

Power

Given that the social cognitive and neural processes of interest are known to exhibit considerable maturation over adolescence, as well as there being some evidence for sex differences in these developmental processes, we chose to restrict the sample to early adolescent females. Doing so limits the potential confounding effects of age and sex, thus increasing power to address our questions of interest. The sample size was specifically based on power analyses calculated for the grant that funded the [deleted] longitudinal project. The power analyses indicated that a sample size of 170 would have adequate power to detect small effect sizes (0.24 or larger) in the main research questions of the grant, pertaining to the relationship between i) puberty and brain function and ii) brain function and mental health.

As such, our final sample size of 125 had excellent power (of 1.0) to detect the larger behavioral (d = 0.47) and neural (d = 1.17) effect sizes for the valuation of disclosure reported by Tamir and Mitchell (2012). A smaller subset of 79 participants were used in certain analyses (refer to Statistical Analyses for further detail), and power calculations were excellent (0.98 or greater) for this group as well.

Study Procedure

Written informed consent was obtained from the parent/guardian, while written assent was obtained from the adolescent participant. At the first visit, the adolescent was screened for MRI eligibility as per procedures determined by the [deleted]. After screening, the parent/guardian and participant completed questionnaires and semi-structured interviews on mental health. The participant also completed the vocabulary and matrix reasoning subtests of the Wechsler Abbreviated Scale of Intelligence, second edition. During the second visit, scheduled approximately one month from the first visit, participants completed the MRI portion of the study as well as additional questionnaires and behavioral tasks. Participants were compensated for their time, and all materials and procedures were approved by the Institutional Review Board at the [deleted].

Self-Disclosure Task

In the self-disclosure task, participants were presented with statements about the self that they could choose to share with a friend or keep private. The friend was chosen prior to the MRI scan and remained constant across both runs of the task. Participants were told to choose a close friend (ideally their best friend of the same gender) with whom they would regularly share both superficial and intimate information. Five participants (4%) chose a male friend, and two participants (2%) chose a similar-aged relative as they did not have such a close female friend. To increase ecological validity, participants were prompted to share their response to one randomly selected trial from the task in real life. They were informed about this prior to the task, and asked to bring a means of communicating with their friend (e.g. phone number or social media app) to the laboratory session. When participants were not able to communicate this information during the session, they were asked to inform their friend in person following the assessment.

In each trial of the task, participants were presented with a statement that was either intimate (e.g. “Sometimes I worry about kissing”) or superficial in depth (e.g. “Sometimes I carry chapstick”), and had to make a binary decision about whether the statement was self-descriptive (“yes” or “no” via left- and right-hand button press, respectively). These items were created following a focus group discussion with adolescent girls. Items were chosen such that positively and negatively valenced statements were included in both intimate and superficial conditions. However, we note that more negative items were present in the intimate condition given that these disclosures constitute sharing information that is more emotionally intense and oftentimes embarrassing (Howell & Conway, 1990). The full list of intimate and superficial statements used in this task is presented in Table S2. After making this choice, they were presented with the option of either sharing this statement and associated choice with their chosen friend, or keeping it private. Thus each trial varied in depth (intimate or superficial) and consisted of two decisions (self-evaluation, followed by disclosure). Each disclosure choice to “keep it private” or “share with friend” was associated with two to four gold coins worth one cent ($0.01) per coin. Participants were informed prior to the task that they would receive all money earned in this task. They were free to increase their monetary payout by consistently choosing the option with a greater number of gold coins. Therefore, choosing the option with fewer gold coins reflects the intrinsic reward value of that choice outweighing the monetary value of the alternative. The button press associated with each choice was counterbalanced such that for roughly 50% of participants, the option to share the item was associated with the right button, and for the remaining participants it was associated with the left button. Participants completed 41 trials in each of two runs of the self-disclosure task. The presentation sequence was optimized to obtain maximal contrast detection between statement depth (intimate vs. superficial) and numbers of gold coins associated with the disclosure (loss to share, gain to share and equal value; Wager and Nichols, 2003). Task designs were created with trials lasting an average of 7.68s (range 7.52s – 8.20s). Of the trial length, the self-evaluative phase lasted 4.5 seconds and was separated from the disclosure phase by an average of 0.18s, jittered about 0.02s – 0.70s. Trials were separated by presentation of a blank screen (M = 2.59s, range 1.00s – 14.75s). In total, each of the two runs lasted 8 minutes. Refer to Figure 1 for an illustration of the task.

Figure 1.

Schematic illustration of the Self-Disclosure Task

fMRI data acquisition

Data was acquired on a 3T Siemens Skyra MRI scanner at the [deleted]. High-resolution T1-weighted structural images were collected with the MP-RAGE sequence (TE = 3.41ms, TR = 2500ms, flip angle = 7°, 1.0mm slice thickness, matrix size = 256 × 256, FOV = 256mm, 176 slices, bandwidth = 190 Hz/pixel). Two functional runs of T2*-weighted BOLD-EPI images were acquired with a gradient echo sequence (TE = 27ms, TR = 2000ms, flip angle = 90°, 2.0mm slice thickness, matrix size = 100 × 100, FOV = 200mm, 72 slices, bandwidth = 1786 Hz/pixel). There were 225 images per run. To correct for local magnetic field inhomogeneities, a field map was also collected (TE = 4.37ms, TR = 639.0ms, flip angle = 60°, 2.0mm slice thickness, matrix size = 100 × 100, FOV = 200mm, 72 slices, bandwidth = 1515 Hz/pixel).

Behavioral measures of interest

Friendship quality (intimacy, disclosure, and support)

The Intimate Friendship Scale (IFS; Sharabany, 1994) was used to examine the intimate nature of friendships. It is composed of eight dimensions: “frankness and spontaneity”, “sensitivity and knowing”, “attachment”, “exclusiveness”, “giving and sharing”, “imposition”, “common activities”, and “trust and loyalty”. The questionnaire consists of 32 items that are rated on a seven-point Likert scale ranging from “always disagree” to “always agree”. Internal reliability (alphas) of the subscales have ranged from 0.72 to 0.77 (Sharabany, 1994). The Shulman’s Self Disclosure Scale (SSDS; Shulman, Laursen, Kalman, & Karpovsky, 1997) was used to examine adolescents’ tendency to share personal information with their best friend. Three subscales examine disclosure about family, friendship, and physical appearance. The questionnaire consists of 23 items that are rated on a four-point Likert scale ranging from “rarely” to “almost always”. Internal reliability (alphas) of the subscales have ranged from 0.76 to 0.95 (Shulman et al., 1997). Both the IFS and SSDS were completed in relation to the chosen friend on the Self Disclosure Task.

The Multidimensional Scale of Perceived Social Support (MSPSS; Zimet, Dahlem, Zimet, & Farley, 1988) measures perceptions of social support adequacy from three sources: family, friends and a significant other. The 12-item scale uses a 7-point Likert-scale that ranges from “very strongly disagree” to “very strongly agree”. Each subscale (i.e. source of support) is assessed with four items, and we specifically examined the “friends” subscale for these analyses. A number of studies have found the measure to have good internal reliability with diverse samples (Kazarian & McCabe, 1991).

Self-perception

The Self-Perception Profile for Adolescents (SPPA; Harter, 2012) measures an individual’s sense of self-competence on nine domains. We examined three of these domains in the current analyses: “social competence”, “close friendship” and “global self-worth”. The global self-worth domain constitutes a general perception of the self, and is not a summation of domain specific judgments of ability. There are a total of 45 items on the questionnaire, each with two contrasting descriptions (e.g., Some teenagers find it hard to make friends vs. Other teenagers find it pretty easy to make friends). For each description, there are two alternative response choices (sort of true for me vs. really true for me). Respondents are instructed to first choose the description that is most similar to themselves, and then decide how closely the description fits them using the two response choices. Internal reliability (alphas) of the subscales have ranged from 0.74 to 0.92 (Harter, 2012).

Internal reliabilities for all questionnaires in the current sample are reported in Table S3.

Transformations and imputation

All questionnaires aside from the SSDS exhibited negative skew; therefore, they were reverse-scored and log-transformed. The SSDS exhibited positive skew and was log-transformed. Multiple imputation was run on the transformed questionnaire data using the “mice” package (van Buuren & Groothuis-Oudshoorn, 2011) in R to deal with missing questionnaire data (MSPSS N = 3; IFS N = 6; SSDS N = 6; SPPA N = 22). Imputed scores for all questionnaires aside from the SSDS were again reverse-scored (multiplied by −1), so that directionality reflected the raw data.

Statistical Analyses

Behavior

For each participant, the relative monetary value of disclosing i) intimate, ii) superficial, and iii) all information was determined by calculating the point of subjective equivalence (PSE) between sharing information and keeping it private. Specifically, for each statement depth (intimate, superficial), the two disclosure choices (share vs. private) on any given event were associated with monetary values that range from 2 to 4 cents (based on Tamir & Mitchell, 2012). The relative payoff associated with sharing (herein referred to as ShareValue) was calculated as the difference between the values for sharing and private choices (i.e. ShareValue = Share ¢ - Private ¢), ranging from −2 to 2 cents by 1 cent increments. For each amount of ShareValue, we calculated the percentage of trials in which a participant chose to share the information. This resulted in 5 data points per subject, per condition. Cumulative normal curves were fit to these values by implementing a Nelder-Mead simplex search algorithm in Matlab. Cumulative normal distributions were defined on the basis of the following probability density function:

$$\frac{1}{\sqrt{2\pi {\sigma }^2}}{e}^{-\frac{{(x-\mu )}^2}{2{\sigma }^2}}$$

Starting values for this estimation were set at a mean of 0 and an SD of 1, and the search continued for 100,000 iterations, or until a solution was achieved. In situations when participants had highly skewed behavior (e.g. always or almost always chose to disclose regardless of ShareValue; refer to Table S4 for percentages), a solution was not appropriately estimable and final values ranged beyond -$100 or +$100. To deal with these situations, the final solutions of PSE were winsorized to a meaningful range (based on study design) of −$0.02 and +$0.02. A negative PSE indicates more willingness to forfeit monetary reward to share information with peers, reflecting the intrinsic value of disclosure. Conversely, a positive PSE indicates less willingness to forfeit monetary reward. In other words, these participants needed to be paid more money (and were thus less willing) to disclose.

A single sample t-test examined whether PSEs for all items are significantly different from zero. In addition, the nlme package (Pinheiro, Bates, DebRoy, Sarkar, & R Core Team, 2018) in R was used to compare the PSE associated with intimate and superficial conditions (with observations being nested within participants from random effects). The model specification was:

$$PSE\text{=}{\beta }_{\text{0}}\text{+}{\beta }_{\text{1}}·condition\text{+}ϵ$$

$${\beta }_{\text{0}}\text{=}{\gamma }_{\text{00}}\text{+}{v}_{\text{0}}$$

$${\beta }_{\text{1}}\text{=}{\gamma }_{\text{10}}\text{.}$$

Participants whose PSE values were equal to +$0.02 for both intimate and superficial conditions (N = 3), or equal to -$0.02 for both conditions (N = 43), were excluded from this analysis given that the final (winsorized) PSE solutions would not appropriately reflect potential differences between superficial and intimate trials (final N = 79). This model was compared with a null model with no fixed effects using the anova function. The null model was:

$$PSE\text{=}{\beta }_{\text{0}}\text{+}ϵ$$

$${\beta }_{\text{0}}\text{=}{\gamma }_{\text{00}}\text{+}{v}_{\text{0}}\text{.}$$

A significant effect of statement depth was determined based on a p value < 0.05 for the Likelihood Ratio Test comparing the two models.

Linear regressions examined the association between PSEs and socioemotional variables. Specifically, the difference between PSEs for intimate and superficial conditions was the independent variable, and questionnaires were the dependent variable. Three different models were run for friendship quality: IFS, SSDS and MSPSS’s “friends” subscale. Three different models were run for self-perception: SPPA’s “social competence”, “close friendships” and “global self-worth” subscales. For friendship quality and self-perceptions, findings were corrected for multiple comparisons using Bonferroni correction that accounts for the mean correlations between the three outcome variables (Sankoh, Huque, & Dubey, 1997). The mean correlation across outcome variables was 0.293 for friendship quality and 0.494 for self-perception scales. Bonferroni adjusted thresholds for significance were found to be p < 0.023 and p < 0.029, respectively.

fMRI

Raw DICOM image files were converted to the NifTI format with MRIConvert and organized according to the Brain Imaging Data Structure (BIDS) standards that facilitates the use of portable analysis tools called BIDS Apps (Gorgolewski et al., 2017). The fMRI data were then preprocessed using the fmriprep BIDS App (v1.0.0; https://github.com/poldracklab/fmriprep; Esteban et al., 2018), a tool based on Nipype. Each T1-weighted (T1w) volume was corrected for INU (intensity non-uniformity) using N4BiasFieldCorrectionv2.1.0 and skull-stripped using antsBrainExtraction.sh v2.1.0 (using the OASIS template). Brain surfaces were reconstructed using recon-all from FreeSurfer v6.0.1, and the brain mask estimated previously was refined with a custom variation of the method to reconcile ANTs-derived and FreeSurfer-derived segmentations of the cortical gray-matter of Mindboggle. Spatial normalization to the ICBM 152 Nonlinear Asymmetrical template version 2009c was performed through nonlinear registration with the antsRegistration tool of ANTs v2.1.0, using brain-extracted versions of both T1w volume and template. Brain tissue segmentation of cerebrospinal fluid (CSF), white-matter (WM) and gray-matter (GM) was performed on the brain-extracted T1w using fast (FSL v5.0.9). Functional data was motion corrected using mcflirt (FSL v5.0.9). Distortion correction was performed using fieldmaps processed with fugue (FSL v5.0.9). In the case of 1 participant who was missing fieldmaps, “Fieldmap-less” distortion correction was performed by co-registering the functional image to the same-subject T1w image with intensity inverted and constrained with an average fieldmap template, implemented with antsRegistration (ANTs). This was followed by co-registration to the corresponding T1w using boundary-based registration with 9 degrees of freedom, using bbregister (FreeSurfer v6.0.1). Motion correcting transformations, field distortion correcting warp, BOLD-to-T1w transformation and T1w-to-template (MNI) warp were concatenated and applied in a single step using antsApplyTransforms (ANTs v2.1.0) using Lanczos interpolation. Frame-wise displacement was calculated for each functional run using the implementation of Nipype. Many internal operations of FMRIPREP use Nilearn, principally within the BOLD-processing workflow. For more details of the pipeline see https://fmriprep.readthedocs.io/en/latest/workflows.html. Following FMRIPREP, preprocessed output were smoothed in SPM12 using a kernel of 6-mm FWHM Gaussian kernel.

The self-disclosure task was modelled as an event-related design, with subject-level analyses conducted in SPM12. For each subject, event-related effects were estimated according to the general linear model, using a canonical hemodynamic response function, high-pass filtering (128s) to fit the task design, and the ‘FAST’ error structure. Separate regressors were entered for the four main events of interest (2 statement depths X 2 decisions: Intimate Self-Evaluation, Intimate Disclosure, Superficial Self-Evaluation, Superficial Disclosure), with the duration of each event based on reaction time. A separate set of parametric modulators tracked the ShareValue for each of the two disclosure decisions. However, as there was an uneven distribution of ShareValue trials (see Table S5), we re-coded ShareValue to index “loss to share”, “gain to share” or “no difference” (consistent with the model used for optimization of the fMRI task design). This resulted in roughly similar number of trials for each of these three categories. Another set of parametric modulators tracked ShareChoice - the choice of each disclosure decision (i.e. decision to share vs. keep information private). However, the ShareChoice parametric modulators were not modelled in any given run if participant responses were highly biased to a given disclosure response, i.e. more than 90% of trials were either shared or kept private, as outcome effects were not estimable in such situations (27% of participants [34 out of 125] were missing ShareChoice for the Intimate condition and 38% of participants [47 out of 125] were missing ShareChoice for the Superficial condition). In addition, we could not contrast ShareChoice between the Intimate and Superficial condition in 42% of participants [53 out of 125] that were missing either of two conditions. An additional regressor indexed missing disclosure responses. Note that re-running first level analyses without the ShareChoice modulators, thus focusing on the four main effects of interest and the ShareValue modulator (i.e. variables that were modelled for the entire set of participants) did not alter significance of these second-level (group) results.

Four motion parameters (Euclidean distance, Euclidean rotation, and the first derivatives of each of these values) were used as regressors of no interest. An additional trash regressor was identified using an in-house automated motion script that employed machine learning to classify motion based on the motion confounds that were output by the fmriprep BIDS App (Cosme, Flournoy, & Vijayakumar, 2018). Moreover, manual quality checking of trash regressors was conducted for participants with 15 to 20% of “trash” volumes, and problematic volumes were additionally identified through this process. Participants with greater than 20% of volumes identified as trash regressors were excluded from analyses (N = 19). In addition, one participant was excluded as visual inspection of their fixed effects analyses revealed a clear pattern of motion-related stripes that indicated contaminated data.

Linear contrast images were created for each of the four main events (i. Intimate Self-Evaluation, ii. Intimate Disclosure, iii. Superficial Self-Evaluation, iv. Superficial Disclosure). Additional linear contrasts were created for each of the four parametric modulators (i.e. Intimate ShareValue, Superficial ShareValue, Intimate ShareChoice, Superficial ShareChoice).

Group level analyses.

Group-level analyses were conducted in AFNI’s 3dMEMA (Chen, Saad, Nath, Beauchamp, & Cox, 2012), which uses both first-level contrasts and the T-statistic images to account for within-subject residuals in the group-level analyses. These analyses were restricted to an explicit mask that was based on the sum of all participants’ gray and white matter masks, thresholded at 15% (i.e. at least 15% of subjects had brain voxels in any given area of the mask). The hypothesized effect of statement depth on disclosure decisions was examined by comparing Intimate Disclosure > Superficial Disclosure. We also examined each of the parametric modulators separately, as well as the difference between the two emotions (i.e. ShareValue for Intimate vs. Superficial, as well as ShareChoice (share > keep private) for Intimate vs. Superficial). Whole brain analyses were corrected for multiple comparison using cluster-wise correction, by employing AFNI’s 3dClustSim. Reported results exceed the minimum cluster size threshold needed for a .05 FWE rate given a voxel-wise threshold of p = .001 (bi-sided, nearest neighbor = 3, k = 73). Smoothness estimates entered into 3dClustSim spatial autocorrelation function (acf) parameters were averaged from each individual’s first-level model residuals, as calculated by 3dFWHMx using the -acf flag (acf parameters: X = 0.735 , Y = 4.659, Z = 12.530). Unthresholded whole brain statistical maps are available on NeuroVault: https://neurovault.org/collections/4493/.

We also examined associations between neural and behavioral responses to self-disclosure. These tests were not included in the pre-registration and were conducted as exploratory analyses. Using AFNI’s 3dttest++, we examined the relationship between PSE and BOLD response to ShareChoice (share > keep private) for the Intimate and Superficial conditions separately, as well as contrasting these conditions (i.e. PSE difference [Intimate PSE - Superficial PSE] related to ShareChoice difference [Intimate ShareChoice - Superficial ShareChoice]). Given the small size of structures of interest, i.e. VTA and NAcc, and the novelty of these analyses, we thresholded at a lowered voxel-wise threshold of p = .005 and cluster-wise threshold of 30, in order to allow readers to explore and generate hypotheses.

ROI analyses.

Activation in independently defined ROIs of the valuation system was examined. A mask of the vmPFC was created based on a recent meta-analysis of mentalizing neuroimaging research (Molenberghs, Johnson, Henry, & Mattingley, 2016), with a 6mm sphere specifically created around the peak of −2 52 −8. Anatomical masks of the left and right VS were extracted from the Harvard-Oxford subcortical atlas, with a 25% probability of inclusion. Contrast estimates for the main events of interest were extracted (as mean of voxels) in each of the three ROIs. For each ROI, a paired-samples t-test examined the difference between the statement depth for i) Disclosure Decisions, ii) ShareValue, and iii) ShareChoice. For each of the three contrasts, Bonferroni correction for multiple comparisons were undertaken that accounted for the mean correlation between the three ROIs (Sankoh et al., 1997). The mean correlation across ROIs was 0.64, and the adjusted threshold for significance p < 0.033. Each of these three contrasts were also related to questionnaire data using linear regressions. Specifically, the beta estimates for each ROI were the independent variable, and questionnaires were the dependent variable. As with behavioral analyses, three questionnaires examined friendship quality (IFS, SSDS, MSPSS’s “friends” subscale), and three questionnaires examined self-perceptions of competence (SPPA’s “social competence”, “close friendships” and “global self-worth” subscales). Bonferroni correction was employed, while accounting for the mean correlation between variables. First, we accounted for the three outcome variables per aim, and then accounted for the three ROIs. This resulted in an adjusted significance threshold of p < 0.016 for friendship quality and p < 0.020 for self-perceptions.

Results

Behavior

Consistent with Tamir and Mitchell’s (2012) landmark study with adults, we found that early adolescent girls were willing to give up “a penny to share their thoughts”. Participants forfeited an average of 0.90¢ per trial (SD: 1.45¢) to disclose information about themselves with their peers, reflecting similar raw effects to those observed in adults (0.97¢ per trial). Specifically, participants gave up 1.16¢ per trial to share superficial information, in comparison to 0.50¢ per trial for intimate information. When ShareValue was zero (i.e. payouts were equivalent for “share” and “keep it private”), participants chose to share the superficial item 73% of the time, in comparison to 62% of the time for intimate items. In support of pre-registered hypothesis 1a, a single sample t-test indicated that the PSE (across both trial types) was significantly less than zero (t ₍₁₀₀₎ = −7, p < 0.001), suggesting that sharing information in general has value. In addition, a linear mixed model examined PSE differences between the superficial and intimate condition (within the subset of N=79 participants that did not have the same winsorized score for both conditions, as described in the methods section with further detail). In support of pre-registered hypothesis 1b, analyses revealed that the inclusion of a main effect of statement depth in predicting PSE significantly improved model fit over the null model of intercept alone (likelihood ratio = 24.2, p < 0.001; AIC difference = −22; see Table 2 for parameter estimates). As illustrated in Figure 2a, the predicted PSE from the statistical model shows that adolescents forfeited more money to share superficial relative to intimate information. In other words, they had to be paid more money to share intimate relative to superficial information.

Table 2.

Linear mixed model statistics

	Std Dev	Estimate	Std Err
Random intercept	0.00007
Residual	1.28
Fixed intercept		0.221	0.145
Depth: Superficial		−1.043	0.205

Figure 2.

Predicted (a) and individual (b) PSE for Superficial and Intimate disclosures. Error bars in (a) represent 95% confidence intervals. PSE = point of subjective equivalence, in cents. Higher PSE indicates greater willingness to forfeit money to in order to self-disclose.

Figure 2b reveals much individual variability in PSE across the two conditions. However, counter to pre-registered hypothesis 1c, these individuals’ variability in PSE difference (calculated as Intimate PSE - Superficial PSE) were not significantly related to friendship intimacy, disclosure, or support (refer to Table S6 for further detail). While PSE difference was not related to social competence either, it was significantly associated to SPPA’s global self-worth (p = 0.019). Further, and inconsistent with pre-registered hypothesis 1d, adolescents with lower levels of global self-worth had much less difference in PSEs for superficial and intimate conditions, compared to adolescents with higher levels of global self-worth who had significantly lower PSEs for superficial than for intimate conditions (see Figure 3). Post-hoc analyses revealed a significant negative association between global self-worth and Superficial PSE (b = −0.858, SE = 0.324, p = 0.009), and a positive, non-significant association between self-worth and Intimate PSE (b = 0.352, SE = 0.346, p = 0.313). Thus it appears that the interaction is particularly driven by girls with higher self-esteem forfeiting more money to share superficial information compared to girls with lower self-esteem.

Figure 3.

Relationship between SPPA global self-worth and PSE. Shaded bars represent 95% confidence intervals.

Brain

Whole brain analyses

Decisions.

Whole brain analyses revealed expansive clusters that exhibited differential response to Intimate-Disclosure and Superficial-Disclosure Decisions (as illustrated in Figure 4, with full results reported in Table S7). Largely in support of pre-registered hypothesis 2b, Intimate-Disclosure elicited greater BOLD response in a large cluster encompassing the dmPFC that extended to the rostral PFC and (predominantly left) lateral PFC. Other clusters exhibited a similar pattern within the right dlPFC, bilateral ATC, left TPJ extending to superior temporal sulcus, right TPJ, precuneus, left lateral occipital cortex, and bilateral caudate. Comparatively, Superficial-Disclosure elicited greater BOLD response than Intimate-Disclosure in the right lateral OFC, SMA and bilateral primary motor cortex.

Figure 4.

Differences in BOLD response (T scores displayed) between Intimate-Disclosure and Superficial-Disclosure Decisions. Results are FWE cluster-corrected at p < .05 (voxel-wise p < .001, k = 71).

ShareValue.

No significant differences in activation were identified when contrasting ShareValue for Intimate-Disclosure and Superficial-Disclosure Decisions (counter to pre-registered hypothesis 2c). Post-hoc analyses conducted within each condition revealed increased activation of the retrosplenial cortex with increasing monetary gains for decisions regarding disclosure of intimate items (i.e. ShareValue for Intimate-Disclosure Decisions). For decisions regarding disclosure of superficial items, there was increased activation of the vmPFC, dorsal ACC, right NAcc, left lateral OFC, hippocampus, and lateral occipital cortex, and bilateral IFG and inferior occipital (lingual) cortex with increasing monetary gains (i.e. ShareValue for Superficial-Disclosure Decisions; see Figure 5).

Figure 5.

BOLD response (T scores displayed) to ShareValue for Superficial-Disclosure and Intimate-Disclosure conditions (relative to baseline). Results are FWE cluster-corrected at p < .05 (voxel-wise p < .001, k = 71).

ShareChoice.

Significant differences in activation when contrasting ShareChoice (share > keep private) for the two statement depths was limited to a small cluster in the brainstem (pre-registered exploratory aim 2a). Post-hoc analyses conducted within each condition revealed that choosing to share intimate information (relative to keeping it private) elicited increased activation of regions that support self-referential thought, such as the vmPFC and precuneus (see Figure 6). Meanwhile, sharing superficial information (relative to keeping it private) elicited increased activation of the left, and to a smaller extent the right, primary motor cortices, supplementary motor cortex, left posterior insula, and left dorso- and rostrolateral PFC.

Figure 6.

BOLD response (T scores displayed) to ShareChoice (share > private) for Superficial-Disclosure and Intimate-Disclosure conditions. Results are FWE cluster-corrected at p < .05 (voxel-wise p < .001, k = 71). The relationship between ShareChoice (share > private) and PSE (T scores) is also illustrated, with positive values reflecting increased BOLD response during share > private in adolescents with higher PSE (i.e. lower intrinsic value), and negative values reflecting increased BOLD response during share > private in adolescents with lower PSE (i.e. higher intrinsic value). These results are thresholded at a lowered voxel-wise threshold of p < .005 and cluster-wise threshold of 30.

Moreover, additional exploratory analyses that were not pre-registered (and conducted with a lowered statistical threshold) revealed associations between individual differences in response to ShareChoice and behavioral valuation of disclosure. For the Superficial-Disclosure condition, a more positive PSE (indicating less willingness to forfeit money for disclosure, or lower intrinsic value of disclosure) was associated with greater dmPFC response when choosing to share information (relative to keeping it private; see Figure 6). For the Intimate-Disclosure condition, a more negative PSE (indicating more willingness to forfeit money for disclosure, or higher intrinsic value of disclosure) was associated with greater right hippocampus and VTA response when choosing to share information (see Figure 6). Finally, when contrasting Intimate and Superficial conditions, adolescents who behaviorally valued intimate disclosure more than superficial disclosure engaged the dmPFC, rostrolateral PFC and mOFC more when sharing intimate relative to superficial items. Whole brain results for associations with PSE are reported in Table S8.

ROI analyses

ROI analyses of the vmPFC, and left and right NAcc, focused on the contrast between Intimate-Disclosure and Superficial-Disclosure Decisions. We failed to identify any significant differences between the statement depths for i) the main effect of disclosure decision, ii) the parametric modulator of ShareValue, or iii) the parametric modulator of ShareChoice (inconsistent with pre-registered aims 2a-c; see Table S9). However, correlations between ROI estimates and questionnaires revealed significant associations for friendship quality (supporting pre-registered hypothesis 2d; see Table 3). As illustrated in Figure 7, adolescents with higher levels of perceived friendship support (MSPSS) exhibited greater vmPFC response to Intimate-Disclosure, relative to Superficial-Disclosure Decisions. Comparatively, there was greater vmPFC response to Superficial-Disclosure, relative to Intimate-Disclosure Decisions in those with less supportive friends. A similar trending effect was present in the vmPFC in relation to friendship intimacy (IFS, p = 0.038. See Table S10 for further detail). Moreover, across the vmPFC and bilateral NAcc, there was greater BOLD response with increasing monetary reward for Intimate-Disclosure in adolescents with closer friendships (IFS), but the opposite pattern was present in those with less close friendships (see Figure 8). Finally, correlations between ROI estimates and questionnaires failed to identify any significant associations for perceived social competence and global self-worth (inconsistent with pre-registered aim 2e; see Table S10).

Table 3.

Significant associations between friendship quality and ROI estimates (Intimate > Superficial).

	ROI	Effect	Beta	Std Err	T-stat	df	p
Decisions
MSPSS	vmPFC	Intercept	−0.780	0.042	−18.570	99.7	0.000
		ROI	0.032	0.013	2.591	118.7	0.011
ShareValue
IFS	vmPFC	Intercept	−0.862	0.028	−30.640	91.1	0.000
		ROI	0.026	0.007	3.763	99.4	0.000
	Left NAcc	Intercept	−0.863	0.029	−29.860	93.1	0.000
		ROI	0.022	0.008	2.618	106.0	0.010
	Right NAcc	Intercept	−0.853	0.029	−29.228	89.8	0.000
		ROI	0.025	0.009	2.732	93.6	0.008

Note: Only results for α < 0.05 are presented. Remainder of the results are presented in Table S10.

Figure 7.

Relationship between vmPFC responses to Disclosure Decisions and perceived friendship support (MSPSS). Shaded bars represent 95% confidence intervals.

Figure 8.

Relationships between BOLD response to ShareValue and friendship quality (IFS). Shaded bars represent 95% confidence intervals.

Discussion

Consistent with a sizeable literature on the theoretical motivations behind self-disclosure, the behavioral and neural findings from the current investigation suggest that adolescents find sharing self-referential information intrinsically rewarding. We significantly expand this perspective by showing the increased risk or “costs” of sharing intimate information when compared to superficial information during early adolescence, as well as important individual differences in valuation.

Disclosure behavior.

In line with prior research using a similar pay-per-view paradigm to examine self-disclosure in adults (Tamir & Mitchell, 2012), adolescents forfeited monetary rewards to share self-referential information with their peers, suggesting that disclosure may itself be a form of subjective reward. In support of our (pre-registered) hypothesis, adolescents also gave up more money to share superficial relative to intimate information, and disclosed superficial information more often than intimate information. These findings suggest they are intrinsically motivated to engage in superficial disclosure more than intimate disclosure. This is consistent with prior research showing that disclosures are more frequently superficial than intimate during the transition from childhood to adolescence, even to close and best friends (Dolgin & Kim, 1994). Adolescents also exhibit mastery of superficial disclosure earlier than intimate disclosure, with the latter continuing to increase over the teen years (Dolgin & Kim, 1994; Jones et al., 1989). Thus superficial disclosure appears to be the prototypic communicative behavior during early adolescence, making it both more highly valued and most likely to be pursued. However, our findings may also reflect a “cost” of intimate disclosure. Communicating personal and affectively-charged information increases the risk of embarrassment and rejection (Omarzu, 2000), which may be compounded by the increased peer sensitivity and anxiety regarding negative social evaluations during adolescence (van den Bos et al., 2014; Westenberg, Gullone, Bokhorst, Heyne, & King, 2007), along with the relative instability of female friendships at this time (Benenson & Christakos, 2003; Bowker, 2004). Thus while prominent theories purport the value of intimacy for relationship development, our findings suggest that superficial disclosure may play a unique role in close friendships during the transition into adolescence. Further longitudinal research is needed to improve our understanding of potential changes in valuation of intimate and superficial disclosure across development. Moreover, consideration of the underlying social and developmental processes may provide insight into other contexts within which individuals may be more motivated to engage in superficial disclosure in close relationships. For example, adults with social anxiety also exhibit heightened fear of embarrassment and rejection, and have been found to report less self-disclosures and intimacy in romantic relationships (Sparrevohn & Rapee, 2009). Our findings thus also highlight the importance of considering a wider away of contexts and transitions that may moderate the degree to which intimate disclosure is valuable for relationship-building.

Beyond group-level effects, individual differences in valuation were associated with perceptions of self-worth. However, inconsistent with our (pre-registered) hypothesis, adolescents with greater self-worth were willing to forgo more money to share superficial relative to intimate information. Post-hoc investigations of this effect revealed that self-worth was not associated with intimate disclosure (i.e. it was valued similarly across adolescents, regardless of their self-worth), suggesting it may be undertaken with caution by the majority of early adolescents. Rather those with higher self-worth were willing to forgo more money to share superficial information compared to those with lower self-worth. This latter effect is in line with literature showing that individuals with higher self-esteem (a global feeling of self-worth) tend to act in a self-promoting manner that calls attention to their good qualities (Baumeister, Tice, & Hutton, 1989; Forest & Wood, 2012). Comparatively, those with lower self-esteem tend to be self-protective in their expressivity due to fears of rejection. In other words, they engage in less disclosures that could reveal their vulnerabilities or flaws due to concerns of disapproval from others (Cameron, Stinson, Gaetz, & Balchen, 2010; Gaucher et al., 2012; Leary, Tambor, Terdal, & Downs, 1995). Interestingly, our findings suggest that adolescents with lower self-worth may be more concerned about potential rejection even in less risky disclosure conditions, given their cautious expression of superficial information. While social cognitive theories and related literature argue that intimate self-disclosure is associated with positive developmental outcomes (e.g. well-being and self-worth) through identity and relationship development during adolescence (Davis, 2012; Harter, 2012), the current findings suggest that superficial-disclosure may instead relate to such outcomes during early adolescence. Given the lack of research that has specifically compared differing depths of disclosure and positive outcomes (such as well-being or self-worth) across any age range, our findings also speak to the importance of considering such individual differences in adults. Further research is therefore needed to understand features that are unique to early adolescence, as well as pathways between depths of self-disclosure and self-worth across different stages of life.

Neural correlates of disclosure.

Early adolescent females exhibited expansive recruitment of social cognitive and emotion regulatory regions when making decisions regarding intimate relative to superficial disclosure. As hypothesized, this included activation within the dmPFC, precuneus, bilateral ATC and TPJ, and left pSTS – all regions that are consistently implicated in mentalizing and perspective taking, in both adults (Molenberghs et al., 2016) and adolescents (Kilford et al., 2016). Intimate disclosure also recruited the left vlPFC and bilateral dlPFC more than superficial disclosure, suggesting increased engagement of regulatory processes. Overall, these results are consistent with more extensive processing of the subjective utility and risk of sharing sensitive and potentially embarrassing information (Omarzu, 2000). Interestingly, activation in a number of regions that have been implicated in social evaluation (i.e. dACC, bilateral vlPFC, left lateral OFC and left hippocampus) was modulated by monetary gain during superficial disclosure decisions, suggesting greater consideration of the social implications of sharing superficial information increased with potential monetary gains. Taken together, early adolescent females need to be paid more to share intimate (relative to superficial) information, and also recruit an extensive set of regions that subserve social and affective processes when doing so. Comparatively, these regions may only be engaged in “high stakes” conditions for superficial disclosure.

The literature on self-disclosure in adults has also identified increased engagement of the mesolimbic dopaminergic system, which has been interpreted to reflect the intrinsic value of sharing information (Tamir & Mitchell, 2012; Tamir et al., 2015). Inconsistent with these prior results, we failed to identify any significant differences in the engagement of this system during intimate relative to superficial disclosure. However, engagement of the vmPFC, NAcc and VTA, all structures that respond robustly to different forms of primary and secondary rewards (Bartra, McGuire, & Kable, 2013), was modulated by monetary reward during decisions about superficial disclosure (although the latter effect did not survive cluster-based thresholding). This suggests that, as a group, the opportunity to share superficial information was increasingly valued with monetary gains by early adolescent females.

While such monetary modulation was not present for intimate disclosure, exploratory analyses also revealed differential engagement of the VTA based on behavioral valuation of intimate disclosure. Specifically, adolescents with a lower PSE (i.e. greater behavioral valuation) in the intimate condition exhibited increased engagement of the VTA when specifically sharing intimate information. This region is one of the primary dopamine producers in the brain, playing a central role in reward and goal-directed behaviors (Morales & Margolis, 2017). We also found that adolescents who behaviorally valued intimate disclosure more than superficial disclosure engaged the dmPFC, rostrolateral PFC and mOFC to a greater extent when sharing intimate relative to superficial items. Thus although early adolescent females as a group give up less money to share intimate information, those that are willing to forfeit more money exhibit more extensive recruitment of social cognitive and emotion regulatory regions, and also show engagement of the valuation system. This may suggest that these adolescents are better able to regulate concerns of negative evaluations and also find these disclosures more rewarding.

Moreover, individual differences in the valuation system were also related to friendship quality. Consistent with our hypotheses, adolescents with less supportive or close friendships exhibited greater vmPFC activation during superficial disclosure decisions, and vmPFC and bilateral NAcc response also increased with monetary rewards for superficial disclosure. Comparatively, adolescents with closer friendships exhibited greater vmPFC and bilateral NAcc activation with increased monetary rewards during intimate disclosure decisions. Given the role of the NAcc and vmPFC in processing motivational salience and reward outcomes respectively (Haber, 2011; Oldham et al., 2018), these findings suggest that adolescents with close friendships had greater anticipation of potential reward, and also received greater subjective value, in the intimate condition. Conversely, those with less intimate friendships had greater anticipation and receipt of reward in the superficial condition. We speculate that these differential neural responses may represent adaptive value-based decision making, since sharing overly personal information can be socially inappropriate and even disadvantageous for less intimate or newer relationships, despite being an important feature of closer bonds (Omarzu, 2000).

Differential engagement of the vmPFC may also reflect self-evaluative processes, which are more likely to involve consideration of other’s opinions during adolescence relative to other developmental stages (Pfeifer et al., 2009). It seems likely that adolescents are undertaking such “reflected-appraisals” when making disclosure decisions (e.g. “will sharing this information change my friend’s opinion of me”). While those with less intimate friendships may be engaging in heightened self-appraisals even when sharing benign statements, those with closer friendships appear to do so only for sensitive and potentially embarrassing information. Given the comparative lack of variability in behavioral phenotypes, future research should consider whether these neural markers can improve our understanding of the relationship between self-disclosure and mental well-being, including the role of social support.

Limitations & conclusions.

To our knowledge, this is the first study to examine the behavioral and neural indices of the intrinsic value of self-disclosure during early adolescence. Our paradigm was designed for ecological validity, with most adolescents performing the task in relation to their chosen “best friend”. Moreover, they were asked to disclose a random item (of those that they had indicated they would share) with that friend following task completion, to increase affective salience and overall engagement. However, the findings should be considered in light of some limitations. The range of ShareValue was not enough to identify differences in PSE for intimate and superficial items for 37% of participants. Relatedly, some participants were missing ShareChoice (i.e. share or keep private) as ShareValue was not large enough to influence their decision on any of the trials (i.e. they either chose to (almost) always share or always keep information private). Therefore, behavioral analyses of PSE differences and fMRI analyses of the ShareChoice parametric modulator was limited to a subset of participants. While prior research has used a similar range of ShareValue, behavioral valuation for disclosure was undertaken prior to the self-evaluative component (Tamir & Mitchell, 2012). Our paradigm may be more ecologically valid, as disclosure tends to follow self-referential thought, but it also suggests that disclosure of known, specific self-relevant content is valued differently to hypothetical information. Future studies may benefit from a larger range of ShareValue to better capture behavioral and neural phenotypes across a broader range of participants when using this paradigm. While our study focused on behavioural patterns of self-disclosures and associated neural responses, we are not able to differentiate between potential underlying mechanisms that contribute to these processes. Future research may thus benefit from asking participants to rate levels of embarrassment, risk, and reward associated with each disclosure decision, in order to tease apart the role of these different mechanisms. Additionally, asking participants to rate intimacy levels of the statements will ensure they agreed with the classification of disclosure depth.

Finally, while our sample characteristics (e.g. community sample of early adolescent females) minimized potential confounding effects from factors of non-interest, it is difficult to make cultural, developmental or sex inferences from this sample. We note that the ethnic and racial diversity in our sample was more diverse than the broader community from which participants were recruited ([deleted]), but also recognise that generalisability to more diverse communities is limited. Future studies that incorporate male adolescents and a more varied racial and ethnic sample will provide valuable insight into sex and cultural differences in close relationships during this period. Longitudinal studies with broader age ranges are needed to understand changes in valuation of self-disclosure over adolescence, including identifying characteristics that are unique to early adolescence. Such developmental analyses, including examination of pubertal effects, are anticipated with future waves of the [deleted] study.

In conclusion, adolescents are willing to forgo monetary reward for the opportunity to disclose self-referential information to a close friend, and these decisions engage an extensive network of regions that support reward, social cognitive and emotion regulatory processes. While behavioral and neural phenotypes of superficial disclosure are influenced by individual differences in self-worth and friendship quality, sharing intimate information may be particularly risky. Overall, these findings suggest that sharing information with peers may be both rewarding and potentially costly during the transition from childhood to adolescence, and highlights the need for further longitudinal research to examine developmental trends.