Spontaneous thought characteristics are differentially related to heightened negative affect versus blunted positive affect in adolescents: An experience sampling study

Abstract Background Mind‐wandering has been linked to negative affect (NA) and depressive symptoms in adolescents. However, mind‐wandering is an extremely broad and heterogeneous cognitive construct. Some features of spontaneous thought may be related to increased NA, whereas others may improve affect, or have no emotional influence. We used ecological momentary assessment (EMA) to investigate the characteristics of spontaneous thoughts in adolescents and their differential relations with moment‐to‐moment affect. Method One‐hundred and sixteen adolescents (ages 13–18; Typical Mood [TM] = 58; Low Mood [LM] = 58) completed 5 days (2–3 times/day) of EMA (total 1037 surveys) assessing current positive affect (PA) and NA and dimensions of spontaneous thought. Multilevel models tested the relation between thought characteristics and affect. Results Relative to the TM group, LM adolescents had a higher frequency of mind‐wandering (38% vs. 56%) and negatively‐valanced thoughts during episodes of mind‐wandering (21% vs. 37%). Negatively‐valenced, self‐referential and past‐oriented thoughts were each associated with higher NA, even when controlling for plausible confounds (e.g., engagement in an unpleasant activity or social interaction, depressive symptom severity). In contrast, task‐focused and positively‐valenced thoughts were uniquely linked to higher PA. Conclusion Characteristics of spontaneous thought—including temporal orientation, self‐referential quality, and task‐relatedness—were differentially related to NA versus PA in adolescents. If replicated, these findings could inform more nuanced assessments of and targeted interventions for specific dimensions of mind‐wandering contributing to high NA versus blunted PA in teens.

Adolescence represents a period of dramatic physical, social, emotional, and cognitive development (Lam et al., 2014;Mills et al., 2014;Nolen-Hoeksema & Hilt, 2008;Sawyer et al., 2012Sawyer et al., , 2018, which contributes to an increasingly rich and complex internal mental world, including frequent mind-wandering toward developmentally salient content (e.g., reflecting on recent conversations or interpersonal events, mentally simulating and rehearsing upcoming social interactions with peers, social comparisons, and other selfreferential thoughts). The brain networks subserving mindwandering and self-referential thought, in particular the Default Mode Network, undergo significant maturation during the transition from childhood to adolescence (Fair et al., 2008;Sherman et al., 2014). At the same time, the prefrontal circuitry underlying the higher-order cognitive abilities (e.g., meta-cognition, attentional control) required to exert control over mind-wandering does not reach full maturity until well into the twenties (Giedd, 2004). In addition, adolescence is a critical period of self-concept formation, heightened sensitivity to social context (in particular with regards to peers), and increased self-referential thinking relative to children or adults (Moses-Payne et al., 2022;Sebastian et al., 2008). There is also evidence that adolescents, relative to children or adults, have heightened negative self-referential thoughts (Moses-Payne et al., 2022), which may mean that thoughts about the self may be more likely to elicit NA during this developmental period. Moreover, studies indicate that the ability to reflect on the perspective of others increases during adolescence, including to inform one's own selfconcept (Dumontheil et al., 2010;Moses-Payne et al., 2021;Pfeifer et al., 2009;Symeonidou et al., 2016). In summary, adolescents may occupy a unique developmental period characterized by an increased propensity to mind-wander-including towards affectively-salient thought content-but are still developing their abilities to regulate these mental states.
Adolescence is also the developmental period during which negative affective states increase in frequency (Bailen et al., 2019;Frost et al., 2015;Griffith et al., 2021;Larson et al., 2002) and, relatedly, rates of depression surge (Avenevoli et al., 2015). The prevalence of interpersonal and other (e.g., academic) stressors during the adolescent years (Hammen, 2009;Nolen-Hoeksema & Hilt, 2008;Rudolph, 2017), coupled with heightened social concerns and a growing capacity for abstract, self-evaluative thought (Aldao et al., 2010;Gaté et al., 2013;Piaget, 1972), may collectively contribute to an increased propensity to mind-wander towards cognitive content that triggers NA. Given that adolescents spend a substantial proportion of their waking hours mind-wandering (e.g., approximately 60% according to a recent ecological momentary assessment [EMA] study; Webb, Swords et al., 2021), research is needed to understand the extent to which these states may contribute to increases in NA. Initial research has been mixed, with some studies indicating that mindwandering is linked to worse affect in adolescents (Mrazek et al., 2013;Webb, Israel et al., 2021), and others failing to support this relationship (Fredrick & Becker, 2021). These inconsistencies may be due to prior research not distinguishing between different relevant characteristics of spontaneous thought. Mind-wandering is an extremely broad and heterogeneous cognitive construct (Smallwood & Schooler, 2015;Wang et al., 2018;Welz et al., 2018). Some forms of spontaneous thought may contribute to increased NA (e.g., negatively-valenced, self-referential thoughts), whereas others (e.g., daydreaming, future-oriented anticipatory pleasure) may improve affect or have no affective consequences. Relevant dimensions of thought that may influence affect include the valence of cognitive content (i.e., unpleasant, pleasant, or neutral thoughts), the temporal orientation (i.e., thoughts focused on the past, present or future) (e.g., Ruby et al., 2013;Smallwood & O'Connor, 2011), and the selfreferential quality of thoughts (i.e., focused on the self, others or neither) (Goldstein, 2016;Hadash et al., 2016). For example, rumination can be considered a subset of mind-wandering that is characterized by repetitive, negatively-valenced, past-focused and self-referential thoughts (for a distinction between rumination and mind-wandering, see Christoff et al., 2016). Rumination prospectively predicts negative emotional states and depression onset (for reviews see Aldao et al., 2010;Nolen-Hoeksema & Watkins, 2011;Watkins & Roberts, 2020), and increases during adolescence (Buerke et al., 2021;Hampel & Petermann, 2005;Sütterlin et al., 2012;Thompson et al., 2010).
Relatedly, in a sample of adults, Ruby et al. (2013) reported that

Key Points
� Smartphone-delivered ecological momentary assessment (EMA) provides a useful tool to sample in-the-moment thoughts and their relationship to affect in the daily lives of adolescents.
� In this study, one-hundred and sixteen adolescents completed 5 days of EMA assessing current positive and negative affect (PA and NA) and dimensions of spontaneous thought.
� Characteristics of spontaneous thought-including temporal orientation, self-referential quality, and taskrelatedness-were differentially related to NA versus PA in adolescents.
� If replicated, these findings could inform more nuanced assessments of and targeted interventions for specific dimensions of mind-wandering contributing to high NA versus blunted PA in teens.
past-oriented thoughts were associated with subsequent low mood, whereas future-related thoughts were associated with improvement in mood.
In the present study, we used smartphone-delivered EMA to investigate several relevant characteristics of spontaneous thoughts in adolescents and their differential relations with moment-tomoment affect. Relative to conventional retrospective self-report questionnaires, EMA allows for a more fine-grained and ecologically valid assessment of fluctuating cognitions and affect in the daily lives of adolescents, while minimizing recall biases by asking youth to report on current thoughts and emotions (Shiffman et al., 2008). In addition, we tested whether dimensions of spontaneous thought may be differentially related to negative affect (NA) versus positive affect (PA), which are only modestly inversely correlated in adolescents (approximate within-person r = −0.30; Herres et al., 2018;Schmidt et al., 2019). Finally, we controlled for several plausible confounds of the relation between mindwandering and affect, including current activity, social context, and depressive symptom severity. These variables may serve as third variable confounds in so far as they predict both worse affect and an increased likelihood to mind-wander. In such cases, mindwandering may be significantly correlated with worse affect, even if mind-wandering is not in fact causally related to affect. For example, to the extent that engagement in a relatively unpleasant activity predicts both worse affect and an increased likelihood to mind-wander, failure to control for such activities would yield a spurious association between mind-wandering and worse affect (assuming they are in fact not causally related to each other).
Similarly, being alone may contribute to relatively poorer affect and promote greater mind-wandering. Finally, individuals with elevated depressive symptoms may have both worse affect and be more prone to mind-wandering (e.g., due to ruminative and other taskunrelated depressogenic thoughts), even if mind-wandering and worse affect are not causally related.
Informed by prior research, we hypothesized that mindwandering would be associated with higher NA and lower PA in adolescents. However, we expected these associations to be no longer significant after controlling for three relevant dimensions of thought (i.e., valence, temporal orientation, and self-referential quality). We predicted that negatively-valenced, past-oriented and self-referential thoughts would be associated with higher NA, whereas positively-valenced, future-oriented, and socially focused cognitions would predict higher PA, even while adjusting for plausible third variable confounds. To increase variability in affect, and given recent evidence of significant differences in the frequency and content of mind-wandering among adolescents with typical mood (TM) versus low/depressed mood (LM) (Webb, Israel et al., 2021), we recruited a sample of LM adolescents in addition to a TM group.
The latter study revealed that LM adolescents had lower PA and both higher NA and rates of mind-wandering than TM adolescents.
The inclusion of both groups increases variance in our predictor and outcome variables, which is necessary for the statistical modeling of their relationships. In addition, it allows for a comparison of the daily (assessed via momentary EMA) affective and cognitive characteristics of a TM group with a sample of teens experiencing depressed affect, which increases in prevalence during the adolescent years.

METHOD Participants
Participants were 116 (TM = 58; LM = 58) 12-18-year olds with English fluency recruited from the greater Boston area. The following exclusion criteria applied to both groups: history of head trauma with loss of consciousness for 2 min or more; history of seizure disorder; serious or unstable medical illness; current use of dopaminergic drugs, cocaine or stimulant (prescribed or illicit); or clinical or laboratory evidence of hypothyroidism. Given that this study was derived from a larger project which included functional magnetic resonance imaging (fMRI), other exclusion criteria included systemic medical or neurological illness that could impact fMRI measures of cerebral blood flow and other standard exclusion criteria for fMRI scanning (e.g., cardiac pacemaker). Given that data for this study were derived from an ongoing clinical trial for adolescents with elevated anhedonia, participants in the LM group received a score of 3 or higher on the Snaith-Hamilton Pleasure Scale (SHAPS; original scoring guidelines) (Snaith et al., 1995), and indicated elevated anhedonia (item score >1) on the Schedule for Affective Disorders and This study is a follow-up to a prior investigation in a smaller sample which focused on the variable of mind-wandering and its relation to resting state brain functional connectivity and affect in adolescents with typical mood versus low mood (Webb, Swords et al., 2021). The present study investigates a much broader set of thought characteristics, including mind-wandering but also the role of thought valence, temporal orientation, and self-referential quality in relation to affect. Forty-nine percent (57/116) of the participants in this study were included in the prior study.

Procedure
The study was approved by the Mass General Brigham IRB. Written informed consent was required from participating parents and SPONTANEOUS THOUGHT CHARACTERISTICS AND AFFECT IN ADOLESCENTS children provided assent (18 year olds provided consent). Following an initial screening session, involving self-report questionnaires (including the SHAPS) and a clinical diagnostic (K-SADS-PL) interview, participants completed an MRI session (see Supporting Information S1 for additional details on measures). Participants completed 5 days of EMA smartphone surveys following their MRI scan (prior to the initiation of therapy in the abovementioned clinical trial from which these data were derived), with surveys triggered 2-3 times per day via popup notifications on teen's smartphones using the Metricwire app. These EMA surveys were delivered Thursday through Monday, two to three times per day, in order to sample current affect and cognitions on both weekdays (i.e., school days) and the weekend (For similar EMA designs in adolescents, see Alarcón et al., 2020;Carper et al., 2022;Forbes et al., 2009, Murray et al., 2022Webb, Swords et al., 2021). EMA surveys were triggered using a timestratified random sampling strategy such that adolescents were signaled once at a random time during two timeslots (4 p.m. to 6:30 p.m. and 6:30 p.m. to 9:00 p.m.), with surveys separated by at least 1 h. To not disturb students during school, surveys were outside of school hours on weekdays. An additional survey was sent on weekends between 11 a.m. and 4 p.m. Participants were incentivized to complete a higher proportion of EMA surveys, earning $15 and $22.50 if they completed at least 70% or 80% of surveys, respectively. The mean length of time between EMA surveys within a given Note: There were no group differences in sex, race, ethnicity, or age (ps > .65). There were group differences in SHAPS (p < .001) and CESD severity (p < .001), as well as income (p = .025; 16 subjects did not report their income).

Ecological momentary assessment (EMA) measures
Positive and negative affect At each EMA survey timepoint, participants were asked to rate the extent to which they felt "happy," "interested," and "excited," (PA items) and "sad," "nervous," and "angry" (NA items) "right before you started this survey." Participants gave their responses using a 5-point Likert scale, with 1 corresponding to "very slightly or not at all," and 5 corresponding to "extremely." Their ratings for these two groups of emotions were averaged to obtain their mean PA and NA scores for each timepoint. Split-half reliabilities for PA (r = 0.86) and NA (r = 0.88) were high (see Supporting Information S1).

Mind-wandering and related thought characteristics
Participants were asked what they were thinking about "right before you started the survey" and if they were thinking about something other than what they were doing, with an answer of "Yes" being coded as an instance of mind-wandering. They were then asked: (1) if they were thinking about something that had happened in the past, something in the future, or neither (i.e., temporal orientation); (2) if they were thinking about something pleasant, unpleasant, or neutral (i.e., thought valence) and (3) if they were thinking about themselves, someone else, or neither/something else (i.e., self-referential quality).

Current activity
Participants were asked to write down what they were doing when they received the survey and rate how much they enjoyed that activity using a 5-point Likert scale ranging from "very slightly or not at all" to "extremely." Participants also indicated whether they were with someone or alone at the time that they received the survey.

Data analytic plan
To test group differences in categorical outcomes (i.e., mind- self-referential quality, and temporal orientation) as predictors. For those variables with more than two possible levels, dummy variables were used to code them. We also included several plausible confounds of the relation between thought characteristics and affect, including depressive symptom severity, current activity pleasure rating and social context (alone or with someone). Finally, lagged analyses tested whether an independent variable predicted PA or NA at the next timepoint. Given the extended length of time between the last EMA survey of day and the first survey the following day, spaces were added in between days so that lagged analyses only considered associations within days. Analyses with continuous affect (PA and NA) outcomes were conducted with the lme4 (Bates et al., 2014) and lmerTest (Kuznetsova et al., 2017) packages in R, specifying a random intercept and using an intent-to-treat approach (i.e., all subjects included). Time was included as a covariate in all analyses.
To estimate the proportion of variance in PA and NA scores accounted for by our predictors we report the marginal and conditional coefficient of determination (R 2 ) for generalized mixed-effect models. As another approach to interpreting the magnitude of predictor effects, we divided parameter estimates by the mean withinperson SD of NA (0.45) and PA (0.63). For example, assuming analyses reveal a parameter estimate of 0.23 for the association between mindwandering and NA (i.e., NA scores are 0.23 higher, on average, when mind-wandering relative to when one is not mind-wandering) then the effect size (ES) estimate would be 0.51 (0.23/0.45), meaning that the mind-wandering-NA relationship is, on average, approximately half the magnitude of the average within-person SD of NA. The latter ES would be considered a medium effect using guidelines for small (<0.2), medium (0.5), and large (>0.8) effects (Cohen, 1988 power to detect an effect half that magnitude).

Group differences in mind-wandering
The frequency of mind-wandering was higher among LM adolescents (55.6%) relative to TM participants (37.6%). This contrast was statistically significant based on the results of the Bayesian logistic regression: the posterior mean of the log odds ratio of mindwandering between TM and LM was −0.84 and its posterior 95% There were no significant between-group differences in the selfreferential or temporal quality of thoughts during mind-wandering episodes (see Supporting Information S1

Relation between thought characteristics and affect
The relationship between each thought characteristic and NA and PA is displayed in Figures 2 and 3, respectively. In univariate analyses p = .028) at the next EMA timepoint, but not vice versa (i.e., PA and NA did not predict mind-wandering at the next timepoint; ps > .28).
Group (LM vs. TM) did not moderate any of the above concurrent or lagged associations between mind-wandering and NA or PA (all ps > .10), which supports the pooling of these two groups into one analytic sample rather than running separate analyses for each group.
Next, we tested a multivariable model simultaneously including each thought characteristic as predictor variables, which revealed that negatively-valenced, self-referential, and past-oriented thoughts were each associated with higher NA (see Table 2 In contrast, task-related (i.e., not mind-wandering) and positivelyvalenced thoughts, as well as past-oriented thoughts were linked to higher PA (Table 2, right panel). The mean within-person SD of PA F I G U R E 2 Mean negative affect (NA) for Low Mood (LM) and Typical Mood (TM) groups as a function of mind-wandering, as well as the valence, temporal orientation, and self-referential quality of thoughts. Bubble area is proportional to the frequency of ecological momentary assessment (EMA) samples for that group. For example, for the top left panel, the LM group were more likely to report mind-wandering at EMA timepoints relative to the TM group (55.6% vs. 37.6%, respectively). The bubble sizes are proportional to these percentages. *p < .05; **p < .01; ***p < .001

F I G U R E 3
Mean negative affect (NA) for Low Mood (LM) and Typical Mood (TM) groups as a function of mind-wandering, as well as the valence, temporal orientation, and self-referential quality of thoughts. Bubble area is proportional to the frequency of ecological momentary assessment samples for that group. *p < .05; **p < .01; ***p < .001 Note: For categorical predictors, parameter estimates are provided for each level of a given predictor relative to the reference level (Mind-Wandering = No; Valence = Neutral; Temporal = Neither; Self-Referential = Neither). For example, Temporal (Past) has a parameter estimate of 0.16 for the NA model which indicates that thoughts about the past are, on average, associated with NA levels 0.16 points higher than thoughts about neither the past nor future (adjusting for covariates). Marginal R 2 considers the variance associated with fixed effects, whereas the conditional R 2 takes both the fixed and random effects into account. was 0.63, and thus effect sizes were as follows for task-related thoughts (ES = 0.25), pleasant versus unpleasant thoughts (ES = 0.86), and thoughts about the past (ES = 0.25). There was also a non-significant trend (p = .06) such that future-oriented thoughts were associated with higher PA (ES = 0.14).

T A B L E 2 Relation between spontaneous thought characteristics and negative/positive affect
Finally, identical multivariable models were run with lagged affect scores as the dependent variable. No significant relationships emerged in these models (ps > .14). See Supporting Information S1 for additional analyses and figures.

DISCUSSION
Mind-wandering was common in our adolescent sample, in particular for the LM group (56% of EMA timepoints relative to 38% for TM participants) and was associated with both higher NA and lower PA.
This difference may reflect the fact that the LM adolescents (who had elevated depressive symptoms) were more likely to be engaged in negative, ruminative thought. Indeed, as reported above, the LM group were most often mind-wandering to unpleasant thought content. In addition, the higher rate of mind-wandering in this group may also be due to broader depression-related attentional control impairments (Vilgis et al., 2015;Webb, Israel et al., 2021).
Notably, the relationship between mind-wandering and higher NA was no longer significant when including relevant thought dimensions in our model. Specifically, in the latter model, negativelyvalenced, past-oriented and self-focused thoughts were each independently associated with higher concurrent NA, while adjusting for several plausible confounds. Importantly, these effects emerged from a multivariable model within which each thought characteristic was simultaneously included. In other words, both past-oriented and selffocused thoughts were significantly associated with elevated NA even when accounting for whether these thoughts were negativelyvalenced or not. Although speculative, it may be that even when adolescents' thoughts shift toward past events that are neutral or pleasant, they may be engaging in subtle comparisons which serve to highlight what is lacking in their lives right now relative to back then, resulting in increased NA. Overall, past-oriented thoughts were relatively infrequent (LM = 15.4%; TM = 12.0%), but self-focused thoughts were very common, present at over 40% of EMA timepoints (LM = 44.9%; TM = 42.2%). Prior studies have found pastoriented thoughts to be associated with worse mood in adult samples (Ruby et al., 2013;Smallwood & O'Connor, 2011). However, we are not aware of any prior studies in adults or youth showing that selffocused thoughts are associated with worse mood independent of the valence of those thoughts. Given that adolescence is a critical period for self-concept formation, it may be that self-focused thoughts often breed judgments or comparisons (e.g., between self and other peers, or current self and ideal/future self) that increase NA in the moment. In addition, although the clinical psychological literature has focused on the effects of negative self-referential thinking (e.g., rumination) on mood, contemplative wisdom traditions-most notably Buddhism-have emphasized the much broader role of self-referential thought in contributing to unhappiness (Goldstein, 2016;Hadash et al., 2016). Indeed, there is emerging evidence that changes in self-referential thinking may be one key mechanism through which mindfulness training exerts its beneficial effects on mood and internalizing symptoms (Lin et al., 2018), and that mindfulness training-with its emphasis on cultivating nonjudgmental present-moment awareness-is most beneficial for those adolescents with a greater tendency towards maladaptive selfreferential thinking patterns Webb, Swords et al., 2021).
In contrast to the NA findings, mind-wandering remained significantly associated with lower PA, even after adjusting for other thought characteristics and plausible confounding variables. In other words, thinking about something other than what one is currently doing is still significantly associated with lower PA even after controlling for the effect of thought valence, temporal orientation, and self-referential quality. It may be that focusing attention on the task at hand is more likely to promote positive affective states (e.g., stimulate interest in the current activity or promote savoring and experiential pleasure) than to reduce negative emotional states (Blanke et al., 2018). Being fully attentive to what one is currently doing may promote interest and pleasure in an activity, but may also inhibit task-unrelated thoughts that interfere with PA. Alternatively, low levels of PA (e.g., boredom) may promote greater mindwandering.
The association between past-oriented thoughts and greater PA was unexpected and seemingly contradicts the abovementioned finding that thoughts about the past were associated with higher NA.
However, PA and NA are only modestly inversely correlated within individuals (r = −0.26 in the present study). In other words, elevations in NA do not necessarily correspond with decreases in PA, and both elevated NA and PA can co-occur simultaneously. For example, an adolescent could be thinking about a past event that simultaneously increases anxiety (i.e., higher NA), as well as interest or excitement (i.e., higher PA). It should also be noted that in univariate analyses (i.e., not including covariates; see Figure 3) thoughts about the past were not significantly related to PA. There was also a nonsignificant trend of future-oriented thoughts, which were very common (present at well over half of EMA timepoints; LM = 57.4%; TM = 68.1%), being associated with higher PA. With regards to covariates, it also worth noting that being with someone (relative to being alone) at the time of the EMA survey was significantly associated with higher PA but not lower NA (see Table 2).
The concurrent associations between spontaneous thought characteristics and worse affect could be due to the former causing the latter and/or vice versa (or be due to a third variable confound not included in our models). Lagged analyses were conducted to test the directionality of these associations. In a multivariable model (i.e., simultaneously including all thought characteristics and covariates) no lagged associations were significant (lagged associations were detected in a univariate model with mind-wandering predicting higher NA and lower PA at the next EMA timepoint, but NA/PA were not associated with future mind-wandering). There are a few EMA studies-primarily conducted in adult samples-that have tested lagged associations between mind-wandering and affect (or related emotional well-being constructs). Some of these studies provide support for mind-wandering predicting future mood states (e.g., Killingsworth & Gilbert, 2010;Ruby et al., 2013;Welz et al., 2018), whereas others have found support for the reverse association, or a bidirectional relation (e.g., Webb, Israel et al., 2021). It is important to note that, in the present study, the average length of time between  (Gibb et al., 2022). Of relevance, there is a substantial body of research showing that experimentally inducing negativelyvalenced categories of mind-wandering focused on the past (i.e., rumination inductions; e.g., Donaldson & Lam, 2004;Lavender & Watkins, 2004;Nolen-Hoeksema & Morrow, 1993) or future (i.e., worry inductions; e.g., Frala et al., 2014;Llera & Newman, 2010) cause worse mood. Future studies could consider experimentally inducing specific facets of mind-wandering (e.g., self-referential thoughts vs. mind-wandering unrelated to the self) and assess impacts on PA versus NA. In summary, the relationship between mind-wandering and affect is likely bidirectional, moderated by content (e.g., valence of thoughts), and time-limited (i.e., the effect of spontaneous thought on affect, and vice versa, may dissipate more quickly than can be captured by the EMA sampling frequencies used in most studies).
The present study was part of a larger project focused on recruiting adolescents with elevated anhedonia (LM group) and a control group (TM group). The inclusion/exclusion criteria were such that the LM group had elevated anhedonia and overall depressive symptoms, and a number of LM participants had MDD and/or anxiety disorders, as these were not exclusionary. In contrast, the TM group were free of any psychiatric diagnoses and had low levels of depressive symptoms and anhedonia. Although these inclusion/ criteria ultimately provided meaningful variance in our predictor and outcome variables (e.g., see Figure 2), the inclusion of two relatively bimodal groups may have increased the chances of identifying group differences. Future studies could examine the extent to which the present findings are replicated using alternative inclusion/exclusion criteria.