Electrophysiological effects of smartphone notifications on cognitive control following a brief mindfulness induction.

Smartphone use is nearly ubiquitous, with 93% of adults among economically developed countries, including the United States, Canada, Israel, and South Korea owning a smartphone (Taylor & Silver, 2019). Multiple studies have demonstrated the distracting effects of smartphone notifications on behavioral measures of cognition. Fewer studies have examined the effects of notifications on neural activity underlying higher-level cognitive processes or behavioral inductions to reduce smartphone-related distraction. Using EEG spectral frequency power densities, we assessed the effects of smartphone notifications (vs. control trials) on engagement of attentional shifting processes involved in cognitive control during a Navon Letter visual oddball task. Participants were randomly assigned to a brief mindfulness induction (N = 44) or a neutral narration control condition (N = 43). Overall, participants had lower theta-band power, but higher alpha- and beta-band power densities on target letter trials preceded by smartphone notifications. Additionally, participants in the mindfulness (vs. control) condition had a larger attention shifting oddball assessed via theta power density and theta/beta ratio (TBR) values-reflecting increased engagement of cognitive control-particularly on smartphone notification (vs. control) trials. Altogether, these results provide evidence supporting the idea that smartphone notifications can decrease activity of neural correlates of cognitive control, and offer the promise of a brief mindfulness induction to buffer against the effects of smartphone notifications on cognitive control. The findings indicate a need for further research on mindfulness inductiosn as a means to reduce potential distraction caused by smartphones.

Social concerns about anxious arousal explain the association between neural responses to anxious arousal pictures and social anxiety.

Cognitive theories propose that social anxiety disorder involves heightened attention to anxious arousal symptoms due to worries that they may evoke rejection from others. Supporting this, studies have shown that social anxiety is related to greater attention to representations of anxious arousal and to anxiety sensitivity social concerns, which refers to sensitivity to feelings of anxious arousal during social situations. However, this has not yet been tested using neural indices of attention to images depicting anxious arousal. To examine these associations, the current study examined early and sustained attentional bias to anxious arousal images using the P2 and the late positive potential (LPP), respectively. Electroencephalogram data were collected while a non-clinical sample of undergraduate students (N = 106) viewed images of people exhibiting anxious arousal in addition to blocks of negative and neutral images from the IAPS. The neural response to anxious arousal images was isolated using residual scores (e.g., using linear regression to predict the P2 elicited by anxious arousal images from the P2 elicited by neutral images (P2neutral→AA) or negative images (P2negative→AA), then saving the unstandardized residuals). There was an indirect effect of the P2neutral→AA and P2negative→AA waveforms that was explained by anxiety sensitivity social concerns. Additionally, there was an indirect effect of both LPP waveforms on social anxiety symptoms during the early time window of the LPP (400-700 ms). At the later time window of the LPP (700-1000 ms), there was an indirect effect of the LPPneutral→AA residual waveform, but not the LPPnegative→AA, on social anxiety symptoms.

The association of emotion regulation with distress tolerance depends on a neural correlate of cognitive control.

BACKGROUND: Distress tolerance is associated with transdiagnostic mental health problems. Theory and research implicate emotion regulation and cognitive control as factors in distress tolerance but their unique contributions and interdependency have been unclear. This study tested how emotion regulation and the N2, a neural index of cognitive control, uniquely and interactively predicted distress tolerance. METHODS: Undergraduate psychology students (N = 57) completed self-report measures and a Go-NoGo task, from which the N2 was extracted using PCA. The Go-NoGo task was counter-balanced to avoid confounding stimulus characteristics and frequency of stimulus presentation. RESULTS: Emotion regulation predicted distress tolerance, but the N2 did not. The association of emotion regulation with distress tolerance was moderated by the N2, such that the association was larger at higher N2 amplitudes. LIMITATIONS: The use of a non-clinical student sample limits the generalizability of the results. The data are cross-sectional and correlational, preventing conclusions about causality. CONCLUSIONS: The findings indicate that emotion regulation is associated with better distress tolerance at higher levels of N2 amplitude, a neural correlate of cognitive control. Emotion regulation may be more effective at enabling distress tolerance in individuals with better cognitive control. This supports past work indicating that distress tolerance interventions may provide benefit by developing emotion regulation skills. Additional research is needed to test if such an approach is more effective in individuals with better cognitive control.

Understanding the Dimensions of Post-Event Processing: Applying a Bifactor Modeling Approach to the EPEPQ-15.

Social anxiety disorder is maintained in part by rumination about past social experiences, known as post-event processing. The Extended Post-Event Processing Questionnaire (EPEPQ-15) assesses post-event processing as three correlated factors. Competing against this structure is a bifactor model that has not yet been evaluated for the EPEPQ-15. These models were tested for the conventional state version of the EPEPQ-15 and a new trait version in two separate samples (Ns = 327 and 351). In both samples, the fit of the bifactor model was better than that of correlated factor models. Moreover, the results did not support the group factors, indicating that a unidimensional interpretation of the EPEPQ-15 is most appropriate. The general dimension of the EPEPQ-15 was highly correlated with social interaction anxiety, beliefs related to social anxiety, anticipatory processing, and safety behaviors. These results overall suggest post-event processing is best conceptualized as a unitary construct.

Loneliness and Depression in College Students During the COVID-19 Pandemic: the Role of Boredom and Repetitive Negative Thinking.

The COVID-19 pandemic triggered increased rates of depression, especially among college students. Due to social distancing guidelines, loneliness has been suspected as a prominent factor in depression during the pandemic. Research is needed to identify possible mechanisms through which loneliness conveys risk for pandemic-era depression. Two potential mechanisms are boredom and repetitive negative thinking (RNT). This study examined cross-sectional associations between depression, loneliness, boredom, and RNT in a sample of college students (N = 199) in April 2020 immediately following campus closure. Results showed a serial indirect effect of loneliness on depression through boredom then RNT. Moreover, specific indirect effects of loneliness on depression were found through boredom and RNT, individually. Though limited by the cross-sectional design, these data align with cognitive-behavioral theory and identify boredom and RNT as possible mechanisms of the association between loneliness and depression in college students during the COVID-19 pandemic.

Suicide on college campuses: a public health framework and case illustration.

Suicide-related behavior (SRB) is a growing mental health concern on college campuses. We argue that causes of this rising trend go beyond student stress, to include outdated campus policies, overburdened counseling center staffing, and untapped targets for prevention efforts. We outline the social-ecological model applied to suicide and related public health problems. Such a viewpoint provides an example road map to redress suicide and related risk factors (e.g., violence, substance abuse) through multiple levels of prevention-focused programing. Using our SAMHSA-funded campus suicide prevention programmatic approach as a case illustration, we proffer lessons and guidelines for the implementation of a social-ecological suicide prevention program (SESPP). Emphasis is placed on review of evidence-informed prevention programs, utilization of interdisciplinary prevention teams, need for rigorous program evaluation, and consideration of the unique demography of each campus.

Win, lose, or draw: Examining salience, reward memory, and depression with the reward positivity.

The reward positivity (RewP) is a putative biomarker of depression. Careful control of stimulus properties and manipulation of both stimulus valence and salience could facilitate interpretation of the RewP. RewP interpretation could further be improved by investigating functional outcomes of a blunted RewP in depression, such as reduced memory for rewarding outcomes. This study sought to advance RewP interpretation first by advancing task design through use of neutral (i.e., draw) control trials and counterbalanced feedback stimuli. Second, we examined the RewP's association with memory and the impact of depression. Undergraduates completed self-report measures of depression and anhedonia prior to a modified doors task in which words were displayed in colored fonts that indicated win, loss, or draw feedback. Memory of the feedback associated with each word (i.e., source memory) was tested. Results showed that RewP response to wins was more positive than to losses, which was more positive than to draws. The RewP was not associated with depression or anhedonia. The low depression group showed a source memory advantage for win words, but the high depression group did not. Source memory showed small relations to the RewP, but these did not survive Bonferroni correction. Results suggest the RewP is sensitive to salience and highlight challenges in detecting an association between the RewP and depression in modified doors tasks. Findings indicate that depression is related to dysfunctional source memory for reward but not loss and that future research should probe the possible associations between the RewP and memory in depression.

Distinct aspects of emotion dysregulation differentially correspond to magnitude and slope of the late positive potential to affective stimuli.

ABSTRACTEmotion dysregulation (ED) is a transdiagnostic risk factor for several forms of psychopathology. One established, integrative conceptualisation of ED that has informed our understanding of psychopathology (Gratz, K. L., & Roemer, L. (2004). Multidimensional assessment of emotion regulation and dysregulation : development, factor structure, and initial validation of the difficulties in emotion regulation scale. Journal of Psychopathology and Behavioral Assessment, 26(1), 41-54) was recently extended to account for state-level and specifically physiological aspects of ED. As such, the goal of the current study was to assess the degree to which this conceptualisation could be captured using a physiological, state-level index (i.e. the late positive potential; LPP). Participants (N=41; Mage=27.5 years, SD=11.0) completed a trait-based rating scale measure of the extended conceptualisation of ED and viewed a series of images that ranged in valence (i.e. unpleasant, pleasant, and neutral). Multilevel modelling indicated some points of convergence between rating scale scores and the LPP, and other points of divergence. Findings underscore the utility of a multi-method approach to improve understanding of key transdiagnostic characteristics across levels of analysis. Further, results are novel evidence supporting validity of the extended conceptualisation of ED.

Attentional Control Moderates the Relations between Intolerance of Uncertainty and Generalized Anxiety Disorder and Symptoms.

BACKGROUND: Intolerance of uncertainty (IU), perceived attentional control (AC), and poor cognitive control abilities are risk factors for anxiety; however, few studies have examined their interactive effects in relation to anxiety. A more complete understanding of interplay between IU, perceived AC, and cognitive control could inform intervention efforts. METHODS: The current study examined the direct and interactive effects of IU and AC on anxiety in a sample of 280 community outpatients (M age = 36.01 years, SD = 16.17). Perceived AC was measured using self-report and cognitive control abilities were measured using a Go/No-Go task. RESULTS: Findings indicated a significant IU by perceived AC interaction predicting worry and GAD diagnoses. There was a positive relation between IU and worry/GAD diagnoses that was strongest among those with high perceived AC. Perceived AC was unrelated to cognitive control abilities, and cognitive control abilities did not interact significantly with IU. Cognitive control abilities were related to worry symptoms but not to GAD diagnoses. CONCLUSIONS: These results indicate that at high levels of perceived AC, individuals with elevated IU report higher levels of worry, potentially due to the conscious use of worry as an emotion regulation strategy. Clinical implications and future directions are discussed.

Anxiety Sensitivity and Arousal Symptom Implicit Association Task Performance: An Event-Related Potential Study of Cognitive Processing of Anxiety-Relevant Stimuli.

BACKGROUND: Anxiety sensitivity (AS), or the fear of anxious arousal, is a transdiagnostic risk factor. Despite the proliferation of self-report research showing AS is related to anxiety, cognitive processes underlying AS are poorly understood. Specifically, AS may reflect processes related to early attentional orientation and response monitoring (reflecting automatic processes), or later engagement and assigning emotional salience towards stimuli (reflecting conscious processes). METHODS: To elucidate cognitive processes underlying AS, event-related potential (ERP) components were elicited in the current study during a novel implicit association task (IAT) in which participants paired self (versus other) words with anxious arousal (versus calm) words. Analyses were then conducted in a sample of community adults (N = 67; M age 39.43, SD = 15.33, 61.2% female) to investigate the association between AS and ERP markers indicative of cognitive processing derived during the IAT. RESULTS: AS was not related to performance on the arousal-IAT and that ERP components did not differ by IAT condition. AS predicted overall late positive potential (LPP) amplitude, particularly in the me/anxiety condition. Elevated IAT scores (reflecting greater ease pairing self-words with anxiety-words) predicted greater P300 amplitude in the me/anxiety condition. LIMITATIONS: The sample was relatively small, and bottom-up processes were not assessed. CONCLUSIONS: These findings are inconsistent with the claim that AS is related to top-down cognitive processes driving self-arousal automatic associations. Instead, AS may relate to cognitive processes regulating emotional engagement with stimuli. Further investigations of cognitive processes underlying AS are needed to inform novel interventions targeting AS.

A multimethod investigation of the impact of attentional control on a brief intervention for anxiety and depression.

OBJECTIVE: Anxiety sensitivity (AS; fear of anxiety) is a malleable risk factor for anxiety and depression. Brief computerized interventions, including elements of psychoeducation, interoceptive exposure, and cognitive bias modification (CBM) can reduce anxiety and depression through AS reductions. These interventions are not equally efficacious for all who receive them, suggesting the need to explore moderators. Attentional control (AC), the ability to regulate attentional processes by focusing and shifting attention as needed, has been linked to AS, anxiety, and depression suggesting that it may moderate treatment efficacy. The moderating effects of self-report and neurophysiological (i.e., theta/beta ratio, occipital alpha power) indices associated with AC processes on a brief AS-focused intervention were examined. METHOD: Participants (M age = 36.43, SD = 16.47; 57.5% female) were randomized to cognitive AS treatment (n = 67) or a repeated contact control (n = 60). RESULTS: Occipital alpha power moderated the rate of change in AS across three weekly treatment sessions as well as the effects of the intervention on anxiety and depression symptoms at the 1-month follow-up. Lower alpha power was associated with a swifter reduction in AS symptoms and marginally lower levels of anxiety and depression at follow-up. AC indices were not correlated with each other. CONCLUSIONS: These findings present a novel hypothesis that lower AC as indexed by occipital alpha power might increase treatment gains in the context of a brief transdiagnostic treatment for anxiety and depression. These findings also highlight the need for external validity studies of AC indices. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Worry as a mediator between psychosocial stressors and emotional sequelae: Moderation by contrast avoidance.

BACKGROUND: Worry is the core feature of generalized anxiety disorder (GAD), which is prevalent among emerging adults. The contrast avoidance model proposes that individuals with GAD use worry to avoid negative emotional contrasts by maintaining a state of negative affect. Research suggests worry in response to stressors increases anxiety, but more research is needed to examine depression as an outcome and the predictions of contrast avoidance in the context of multiple stressor subtypes. The current study examined whether worry may be associated with increased symptoms of anxiety and depression, regardless of stressors, due to the use of worry as an avoidance strategy, moderating these associations. METHODS: 367 undergraduate college students from a medium-sized, public university completed self-report questionnaires online. RESULTS: Worry significantly mediated the associations from academic stressors and social stressors to symptoms of anxiety and depression. Contrast avoidance significantly moderated associations between academic stressors and worry as well as worry and anxiety. For those high in contrast avoidance, worry was relatively high regardless of academic stressors; for those low in contrast avoidance, students with fewer academic stressors reported less worry. LIMITATIONS: The present study relied on self-report. In addition, the cross-sectional design limits the ability to draw conclusions about temporal relations. CONCLUSIONS: Contrast avoidance elevated worry regardless of academic stressors, and strengthened the association between worry and anxiety but not worry and depression. Individuals who experience high levels of contrast avoidance may benefit from cognitive interventions focusing on reducing beliefs about the perceived benefits of worry.

Gender differences in the relation between the late positive potential in response to anxiety sensitivity images and self-reported anxiety sensitivity.

Anxiety sensitivity (AS), or the fear of anxious arousal, is a transdiagnostic risk factor predictive of a wide variety of affective disorders. Whereas AS is widely studied via self-report, the neurophysiological correlates of AS are poorly understood. One specific issue this may help resolve is well-established gender differences in mean levels of AS. The current study evaluated late positive potential (LPP) for images designed to target AS during an emotional picture viewing paradigm. Structural equation modeling was used to examine convergent and discriminant validity for self-report AS and the LPP for AS images, considering gender as a potential moderator. Analyses were conducted in an at-risk sample of 251 community adults (M age = 35.47, SD = 15.95; 56.2% female; 53.6% meeting for a primary Axis I anxiety or related disorder). Findings indicated that the AS image LPP was significantly, uniquely associated with self-report AS, controlling for the LPP for unpleasant images, in females only. Mean levels of AS self-report as well as the AS image LPP were higher in females than in males. These findings provide initial support for the AS image LPP as a useful neurophysiological correlate of AS self-report in females. These findings also provide support for a biological cause for gender differences in AS. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Killing during combat and negative mental health and substance use outcomes among recent-era veterans: The mediating effects of rumination.

OBJECTIVE: Although killing in combat is associated with negative mental health outcomes and hazardous alcohol use, mechanisms that underlie this risk are not well understood. To our knowledge, this present brief report is the first to use mediation analysis to examine associations between killing in combat, distinct facets of rumination (problem-focused thoughts, counterfactual thinking, repetitive thoughts, and anticipatory thoughts), and negative mental health outcomes (i.e., depression, anxiety, PTSD, suicidality) and hazardous alcohol use. METHOD: Participants were a community sample of 283 military personnel (158 males [60.31%]; mean age = 32.61 [SD = 7.11]) who had deployed in support of recent wars in Iraq or Afghanistan. Participants completed an online self-report survey. RESULTS: Three rumination facets (i.e., problem-focused thoughts, counterfactual thinking, and anticipatory thoughts) uniquely (controlling for effects of other rumination facets) mediated the associations between killing in combat and negative mental health outcomes and hazardous alcohol use. Taken together, killing in combat was associated with higher levels of each rumination facet, which in turn were distinctly associated with more negative symptoms of mental health and more hazardous drinking (problem-focused thoughts were the only facet to mediate all effects). Beyond these significant mediation effects, killing in combat still had a significant direct effect on every outcome. CONCLUSION: These findings provide preliminary support for associations between killing in combat and negative mental health outcomes and hazardous alcohol use. Furthermore, rumination (particularly problem-focused thoughts) may be an important consideration in the evaluation and care of recent-era combat veterans. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Examination of evaluative threat in worry: Insights from the Error-Related Negativity (ERN).

Recent research suggests atypical error-monitoring is important to understanding pathological anxiety. Because uncertainty is a transdiagnostic factor associated with anxiety and related disorders, recent research has begun to examine the influence of uncertainty in error-monitoring. Moreover, task irrelevant threat has been shown to influence cognitive performance in individuals with maladaptive anxiety. The current study aims to merge these literatures by examining the influence of task-irrelevant uncertain evaluative threat on error-monitoring using an event-related brain potential, the error-related negativity (ERN). Considering extensive literature indicating a relationship between worry and the ERN, worry was included as a continuous predictor in the analyses. Participants were randomly assigned to either a condition of negative or uncertain evaluative threat to determine their influence on error-monitoring in a Flankers task. Results for the ERN suggest that the ERN was significantly reduced only for the uncertain evaluative threat condition. The current study suggests that uncertain evaluative threat distractors result in a subsequent reduction in error-monitoring. This is consistent with literature suggesting that anxiety impairs inhibition of attentional processing of task irrelevant threatening information. This study adds to the burgeoning literature on the malleability of the ERN. Future research is needed to determine the mechanisms underlying this effect.

The relationship between social anxiety and heartbeat evoked potential amplitude.

Past research suggests that social anxiety is associated with increased processing of cardiac activity. Cognitive theories propose that this is one aspect of self-focus, which is driven by concerns that features of the self, such as anxiety symptoms, will elicit evaluation from others. We investigated the relationship of social anxiety to the cortical processing of heartbeats as reflected in the heartbeat evoked potential (HEP) during false feedback of accelerated heart rate. Thirty-eight participants with high social anxiety (HSA; n = 19) and non-elevated social anxiety (NSA; n = 19) completed a cognitive task during which false feedback of accelerated heart rate was randomly provided on 50% of trials. HEP amplitude was larger in HSAs, but not NSAs, during false heartbeat acceleration cues compared to standard cues. HEP amplitude also was larger in HSAs compared to NSAs during acceleration cues. HEP amplitude during acceleration cues, but not standard cues correlated with social anxiety. Within the first second after the R-peak, social anxiety correlated with voltage at Fz from 223 to 305 ms. Social concerns about the consequences of anxiety symptoms accounted for an indirect relationship between social anxiety and the HEP. These data extend prior evidence of increased processing of cardiac activity in socially anxious individuals, providing support for cognitive theories.

PTSD symptoms and overt attention to contextualized emotional faces: Evidence from eye tracking.

Abnormal patterns of attention to emotional faces and images are proposed by theories of posttraumatic stress disorder (PTSD), and this has been demonstrated empirically. However, few studies have examined how PTSD symptoms are associated with attention to emotional faces in the context of emotional background images. Eye tracking data were collected from seventy-eight undergraduates with a history of experiencing at least one traumatic event as they completed the Contextual Recognition of Affective Faces Task (CRAFT; Milanak and Berenbaum, 2014), which requires subjects to identify the emotion depicted by faces superimposed on an emotional background image. Greater PTSD symptom severity was associated with more time spent looking at background contexts and less time looking at target faces. This is consistent with greater susceptibility to distraction by task-irrelevant emotional stimuli. The duration of each gaze fixation upon fear faces was shorter for those with greater PTSD symptoms, and this pattern was marginally significant for disgust faces. These findings suggest that PTSD symptoms may relate to greater attention toward non-facial background scenes and less attention toward facial stimuli, especially when conveying a fear or disgust expression.

The association between PTSD and facial affect recognition.

The major aims of this study were to examine how, if at all, having higher levels of PTSD would be associated with performance on a facial affect recognition task in which facial expressions of emotion are superimposed on emotionally valenced, non-face images. College students with trauma histories (N = 90) completed a facial affect recognition task as well as measures of exposure to traumatic events, and PTSD symptoms. When the face and context matched, participants with higher levels of PTSD were significantly more accurate. When the face and context were mismatched, participants with lower levels of PTSD were more accurate than were those with higher levels of PTSD. These findings suggest that PTSD is associated with how people process affective information. Furthermore, these results suggest that the enhanced attention of people with higher levels of PTSD to affective information can be either beneficial or detrimental to their ability to accurately identify facial expressions of emotion. Limitations, future directions and clinical implications are discussed.

Hyperarousal Symptoms Explain the Relationship Between Cognitive Complaints and Working Memory Performance in Veterans Seeking PTSD Treatment.

OBJECTIVE: Comorbidity and symptom overlap between traumatic brain injury and posttraumatic stress disorder (PTSD) in veterans returning from deployment present challenges with respect to differential diagnosis and treatment. Both conditions frequently manifest with attention and working memory deficits, though the underlying neuropsychological basis differs. This study evaluated whether hyperarousal symptoms explain the relationship between subjective and objective measures of cognition in a veteran sample. PARTICIPANTS AND PROCEDURES: One-hundred three veterans completed the military version of the PTSD Checklist (PCL), the Neurobehavioral Symptom Inventory, and the Wechsler Memory Scale, 3rd edition digit span task with adequate effort. RESULTS: Hierarchical regression suggested that hyperarousal, but not other PTSD symptoms, explained the relationship between neurobehavioral symptoms and cognitive functioning. This relationship was present regardless of whether veterans met full PTSD diagnostic criteria or screened positive on a traumatic brain injury screener and was robust to other moderators. CONCLUSION: These findings highlight the importance of considering traumatic brain injury and PTSD symptom overlap, particularly the relationship between hyperarousal symptoms and attention and working memory deficits, in conceptualizing cases and treatment planning.

Concreteness of idiographic worry and anticipatory processing.

BACKGROUND AND OBJECTIVES: Worry and anticipatory processing are forms of repetitive negative thinking (RNT) that are associated with maladaptive characteristics and negative consequences. One key maladaptive characteristic of worry is its abstract nature (Goldwin & Behar, 2012; Stöber & Borkovec, 2002). Several investigations have relied on inductions of worry that are social-evaluative in nature, which precludes distinctions between worry and RNT about social-evaluative situations. The present study examined similarities and distinctions between worry and anticipatory processing on potentially important maladaptive characteristics. METHODS: Participants (N = 279) engaged in idiographic periods of uninstructed mentation, worry, and anticipatory processing and provided thought samples during each minute of each induction. Thought samples were assessed for concreteness, degree of verbal-linguistic activity, and degree of imagery-based activity. RESULTS: Both worry and anticipatory processing were characterized by reduced concreteness, increased abstraction of thought over time, and a predominance of verbal-linguistic activity. However, worry was more abstract, more verbal-linguistic, and less imagery-based relative to anticipatory processing. Finally, worry demonstrated reductions in verbal-linguistic activity over time, whereas anticipatory processing demonstrated reductions in imagery-based activity over time. LIMITATIONS: Worry was limited to non-social topics to distinguish worry from anticipatory processing, and may not represent worry that is social in nature. Generalizability may also be limited by use of an undergraduate sample. CONCLUSIONS: Results from the present study provide support for Stöber's theory regarding the reduced concreteness of worry, and suggest that although worry and anticipatory processing share some features, they also contain characteristics unique to each process.