Triarchic psychopathy and affective picture processing: An event-related potential study

Abstract

Psychopathy and its precursors appear to be associated with abnormal affective response. For example, individuals high in psychopathy show reduced psychophysiological response to unpleasant stimuli, which might explain low levels of empathy in psychopathic individuals, and their pursuit of individual goals without regard for others’ wellbeing. In keeping with the notion that psychopathology is best represented on a continuum, the triarchic model suggests that psychopathy is characterized by elevations on three traits: boldness, meanness and disinhibition. Understanding how these traits relate to psychophysiological response to emotional stimuli would help validate the triarchic model, while also bridging to other psychopathological spectra (e.g., internalizing psychopathology, which is characterized by low boldness). Here, N = 123 young adults passively viewed unpleasant, pleasant and neutral pictures while subjective and electrocortical response were recorded. Controlling for the other triarchic traits, individuals with higher self-reported meanness had smaller late positive potentials (LPPs) to both pleasant and unpleasant pictures, whereas individuals higher in boldness had larger LPPs to unpleasant pictures. In addition, those higher in meanness rated unpleasant pictures as more pleasant and less emotionally arousing. Disinhibition was not associated with the LPP or ratings. Meanness appears to drive blunted response to unpleasant pictures that has previously been observed among those high on psychopathy, and may also be associated with reduced engagement with generic pleasant stimuli. Moreover, results converge with prior work on other traits of transdiagnostic relevance (e.g., extraversion), as well as internalizing symptoms, providing a bridge between psychopathy and other forms of psychopathology.

Psychopathy has long been conceptualized as a disorder of emotional processing (e.g., Cleckley, 1964). In the past quarter-century, psychophysiological methods have increasingly been used to validate and refine this characterization of psychopathy, by providing sensitive and objective measures of the processing of emotional stimuli. Historically, this work has been largely categorical, examining differences between individuals classified as psychopaths versus non-psychopaths. However, there is a growing literature on this area that examines physiological indicators of emotional processing using dimensional measures of psychopathy. This approach is in line with the Research Domain Criteria (Insel et al., 2010) and other dimensional approaches to the conceptualization and classification of psychopathology (e.g., the Hierarchical Taxonomy of Psychopathology [HiTOP]; Kotov et al., 2017; Kotov et al., 2021). Moreover, it has become clear that dimensional modeling of psychopathy is warranted – particularly given that taxometric research indicates that this disorder exists on a continuum of severity (Haslam et al., 2020).

The triarchic model conceptualizes psychopathy as consisting of elevated scores along three dimensions – meanness, disinhibition, and boldness – that are thought to be underpinned by transdiagnostic, biobehavioral traits that also relate to other forms of psychopathology (Patrick et al., 2009; Patrick, 2022). Evidence of associations between the triarchic dimensions and neurobiological measures of affective response would help validate the triarchic model and could further knowledge of how personality disorders relate to other forms of psychopathology across development (e.g., internalizing disorders; Nolen-Hoeksema & Watkins, 2011).

Of the three triarchic dimensions, meanness corresponds most closely to the dominant characterization of psychopathic individuals as unempathic and cruel. This trait is often described as the hallmark feature of psychopathy and reflects the interplay of antagonistic interpersonal processes with abnormal affective experiences. Individuals who are high in meanness take a manipulative and callous approach to interpersonal relationships and show diminished emotional response to affiliative cues from others. Disinhibition refers to difficulties with self-regulation and a proneness toward externalizing behavior, such as substance abuse (Patrick et al., 2009; Patrick, 2022). In addition to meanness, disinhibition is also widely construed as a core feature of psychopathy (cf. Poythress & Hall, 2011). Boldness, which refers to high levels of social dominance, low anxiety, and facilitated recovery from stressors (Patrick et al., 2009; Patrick & Drislane, 2015; Patrick, 2022), is the most controversial of the three traits in the triarchic model (see Crowe et al., 2021; Sleep et al., 2019). This is because boldness is associated with prosocial and functional characteristics, such as extraversion, social closeness and wellbeing; in addition, boldness is negatively associated with less desirable traits, such as neuroticism and stress reactivity (Anglim et al., 2020; Blagov et al., 2016). Nonetheless, proponents of the triarchic model have argued that boldness is essential to describe the prototypical psychopath (Sörman et al., 2016) and that it accounts for reduced psychophysiological response to threatening stimuli among highly psychopathic individuals (Patrick, 2022). Consistent with this conceptualization, research examining pain perception has found boldness is associated with lower subjective fear ratings, but not increased pain tolerance (Brislin et al, 2016).

Categorical work examining emotion-processing in psychopathy has found that in contrast to those with low levels of psychopathy, who show reduced startle to pleasant stimuli and potentiated startle to unpleasant stimuli, highly psychopathic individuals fail to exhibit potentiation of the startle response to unpleasant stimuli (Oskarsson et al., 2021). These results are thought to reflect a deficit in defensive fear that manifests in reduced sensitivity to other’s distress and a callous interpersonal style. Moreover, attenuated startle to unpleasant stimuli observed at the group level (i.e., psychopaths versus non-psychopaths) appears to be accounted for by the interpersonal-affective facet of psychopathy (Patrick, 1994; Vaidyanathan et al., 2011), which resembles meanness. Although initial evidence of reduced psychophysiological response to unpleasant stimuli in psychopathy came from the startle literature, evidence for this notion has also been found in studies of electrocortical response. For example, the late positive potential (LPP) is a positive-going event-related potential (ERP) component that starts approximately 300ms after stimulus onset, is centroparietally maximal and is larger for emotional (i.e., unpleasant and pleasant) compared to neutral stimuli (Hajcak et al., 2010). Using the LPP, individuals high in psychopathic traits have been found to be characterized by reduced response to unpleasant stimuli when compared to individuals low in psychopathic traits (e.g., Vallet et al., 2020).

In addition to studies that have compared participants with low versus high overall levels of psychopathy, there are several studies that have examined continuous associations between the triarchic traits and neurobiological reactivity to emotional stimuli. These studies have found that individuals higher in meanness exhibit smaller LPPs to unpleasant stimuli (i.e., fearful and sad faces, Brislin et al., 2019; pain, Brislin et al., 2022; interpersonal aggression, van Dongen et al., 2018). In addition, only greater boldness, but not meanness or disinhibition, has been associated with smaller ERPs to unpleasant scenes (Ellis et al., 2017; also see Esteller et al., 2016 for startle). More recently, boldness was found to be associated with more successful modulation of the LPP during both up- and down-regulation (Perkins et al., 2022). Notably, no study has simultaneously examined associations between all three triarchic traits and neurobiological response to both pleasant and unpleasant scenes within a passive picture viewing task. For example, Ellis and colleagues (2017) examined associations between all three traits and the LPP elicited by unpleasant and neutral pictures only, whereas Perkins and colleagues (2022) examined up- and down-regulation of the LPP elicited by unpleasant, pleasant and neutral pictures with only one trait (boldness). In contrast, Brislin and Patrick (2019) examined all three triarchic traits and neurobiological response to facial expressions with different emotional expressions (e.g., anger, disgust, fear, happiness, sadness, surprise) and intensity (low, middle, high), rather than to emotional scenes. Ribes-Guardiola and colleagues (2022) examined all three triarchic traits in relationship to neurobiological response while participants categorized pictures (unpleasant, pleasant, neutral) based on either the emotional content or the color of the frame around the image. In this study, meanness was associated with reduced affective modulation of the LPP, but only when participants were focused on the affective content of stimuli (i.e., when it was task-relevant; Ribes-Guardiola et al., 2022).

As such, unique associations between individual differences in the triarchic traits and the processing of both unpleasant and pleasant scenes in the context of a passive picture viewing task remains unclear. Research examining only one triarchic trait (e.g., boldness in Perkins et al., 2022) cannot determine specific relationships between psychopathy and emotional processing. Moreover, research examining narrow representations of emotional stimuli (e.g., interpersonal aggression in van Dongen et al., 2018) provides information about the processing of specific kinds of stimuli, but not generic stimuli. Studies that manipulate participant emotion regulation (Ellis et al., 2017) or attention to affective content (Ribes-Guardiola et al., 2022) provide information about emotional processing within specific contexts. Knowing whether the triarchic dimensions of psychopathy are related differentially to abnormal responses to unpleasant and/or pleasant stimuli within a passive picture task provides necessary information about general processing of emotional stimuli is critical to a more accurate and parsimonious model of psychopathy and could have implications for its treatment or management. It is possible that the relationship between triarchic psychopathy and neurobiological response to emotional stimuli may vary as a function of task demands and stimulus content depicted. For example, there is evidence that depression is associated with a blunted LPP to generic unpleasant stimuli (MacNamara et al., 2016; Bauer & MacNamara, 2021), but an enhanced LPP to unpleasant stimuli that is self-referential (Speed et al., 2016). Additional empirical work parsing specific associations between triarchic psychopathy and emotional processing using different stimuli and task designs will provide a more comprehensive depiction of the neurobiological underpinnings of psychopathy.

One of the hallmark features of psychopathy is thought to be internal dysfunction that is masked by outward presentation of psychological health (Cleckley, 1964). Therefore, psychopathic individuals might not only show abnormal allocation of attentional resources to emotional stimuli, as measured via the LPP, but might also mischaracterize or misinterpret their emotional experiences. In line with this notion, prior work found that blunted response to unpleasant pictures was specific to the psychophysiological realm and was not evident in subjective ratings (Patrick, 1994). Similarly, boldness (not disinhibition or meanness) was associated with smaller LPPs to unpleasant pictures, but was unrelated to retrospective (after task completion) self-reported intensity of emotional response to these pictures (Ellis et al., 2017). Nonetheless, no work to date has examined associations between the triarchic dimensions and subjective ratings of emotional stimuli on a trial-by-trial level/simultaneous with psychophysiological recording. Ratings made at the end of the task (Ellis et al., 2017; also see Perkins et al., 2022) are necessarily asynchronous and difficult to reconcile with psychophysiological recordings. More fine-grained assessment of subjective response (i.e., measured immediately after psychophysiological response) should provide a more accurate understanding of whether abnormal physiological patterns converge with or diverge from overt reports of emotional response in psychopathy.

Here, we set out to assess unique associations between the three triarchic traits and response to pleasant and unpleasant pictures. By modeling these associations simultaneously for each dependent variable (i.e., the LPP and ratings), we aimed to advance a more complete understanding of neurobiological associations underlying the triarchic model. Moreover, given links between the triarchic traits and other facets of psychopathology (e.g., the internalizing disorders), we aimed to contribute to a growing body of work seeking to advance a more complete, transdiagnostic understanding of psychopathology. Based on prior research, we hypothesized the following relations:

1. Meanness is characterized by poor attachment to others and low empathy (Patrick & Drislane, 2015), suggesting that individuals higher in meanness may show reduced LPPs to unpleasant pictures (Ribes-Guardiola et al., 2022). Prior work did not observe a relationship between meanness and subjective ratings; therefore, we did not expect to find such an association (Ellis et al., 2017).

2. Existing findings relating boldness to the LPP elicited by generic pictures are mixed, with prior research finding that greater boldness related to smaller LPPs to unpleasant pictures (Ellis et al., 2017) or that boldness is not associated with the LPP to unpleasant or pleasant pictures (Perkins et al., 2022). Nonetheless, extraversion – a personality trait closely linked to boldness (Hyatt et al., 2020) – is associated with larger LPPs to unpleasant and pleasant pictures (Speed et al., 2015). Therefore, we hypothesized that boldness would relate to larger LPPs to both unpleasant and pleasant pictures. We hypothesized that boldness would be unrelated to subjective ratings of pictures (Ellis et al., 2017).

3. Prior work has not found that disinhibition is associated with affective abnormalities in psychopathy, at least in the context of a passive picture viewing (e.g., Ellis et al., 2017). For this reason, we did not expect disinhibition to be associated with physiological or subjective measures of emotional processing.

Because ERPs are sensitive to ms-by-ms changes in stimulus response, the LPP can provide a dynamic measure of stimulus processing throughout the duration of picture presentation. Prior work has shown that during earlier portions of stimulus presentation, the LPP is especially sensitive to stimulus content, whereas during later portions of stimulus presentation the LPP also reflects top-down and willful modulations of stimulus processing (Hajcak et al., 2010). Therefore, we measured the LPP in early (i.e., 400-2500 ms) and late (i.e., 2500-5000 ms) time windows during the presentation of pictures, and expected associations between the three triarchic traits to be reflected primarily in the later portion of the LPP (Medina et al., 2016).

Method

Participants

Participants were 123 undergraduate students (M = 19.05 years, SD = 1.00; 53.7% female; 43.1% male) who were recruited into the study after completing the Triarchic Psychopathy Measure (TriPM; described below) as part of a university psychology human subjects pool pre-screen administration. Participants were predominantly White (78.9%), with some individuals reporting Black or African American (1.6%), American Indian or Alaska Native (.8%), Asian, Hawaiian Native, and Pacific Islander (8.1%), or Other (7.3%). Additionally, 15.4% of participants reported they identified as Hispanic or Latino. We oversampled participants at high and low ends of self-reported Boldness and Disinhibition (i.e., ≥ 66^th percentile and ≤ 33^rd percentile) as part of a broader study, in order to ensure sufficient range in TriPM scores. Because some time had passed between when participants had initially completed the TriPM (at the beginning of the semester) and their lab visit, all participants completed the TriPM again at the time of data collection, and these scores were used in analyses.

Materials

Triarchic Psychopathy Measure.

The TriPM (Patrick, 2010) is a 58-item measure of Boldness (social potency, low anxiety, stress immunity), Meanness (callousness, interpersonal antagonism, poor attachment), and Disinhibition (poor self-regulation). Items were rated using a four-point scale (0 = false, 1 = mostly false, 2 = mostly true, 3 = true) and higher scores reflect greater levels of triarchic psychopathy. Scores were computed separately for each subscale by averaging item responses (e.g., Ruchensky et al., 2018).

Means (SD) and ranges for each TriPM scale (collected in lab) were as follows: Boldness (α = .87; M = 1.79; SD = .49; Min = .63; Max = 2.68), Meanness (α = .89; M = .65, SD = .46; Min = 0; Max = 2.21), and Disinhibition (α = .85; M = .73, SD = .40; Min = .10; Max = 2.10). Triarchic scales correlated as follows: Boldness with Meanness (r = .25, p = .01), Boldness with Disinhibition (r = −.20, p = .03), and Meanness with Disinhibition (r = .45, p < .001).

Stimuli.

Twenty-four unpleasant, twenty-four neutral, and twenty-four pleasant pictures¹ were selected from the International Affective Picture System (IAPS; Lang et al., 1999). For unpleasant pictures, the picture content was as follows: bodily injury (45.8%), threatened injury/death of human (29.2%), vehicle crash scene with no injury depicted (16.7%), other (8.3%). For neutral pictures, the picture content is as follows: household object (58.3%), manmade neutral location (20.8%), neutral person or animal (12.5%), other (8.3%). For pleasant pictures, the picture content was as follows: non-explicit erotica (45.8%), attractive person (25%), affiliative people, romantic (16.7%), cute/happy person (8%), other (4%).

Self-Assessment Manikin.

Visual analog scale, the SAM (Bradley & Lang, 1994), was used for rating valence (1 = unpleasant to 9 = pleasant) and arousal (1 = low arousal to 9 = high arousal) of pictures.

Procedure

Participants completed the TriPM followed by a passive picture viewing task. During the task, participants were instructed to view a series of pleasant, unpleasant and neutral pictures presented onscreen. Pictures were blocked by valence such that there were three blocks of 24 pictures each across the task (pleasant, neutral and unpleasant), with block order randomized for each participant (Pastor et al., 2008; Schupp et al., 2012). Each picture was presented for 5000 ms, followed by a white fixation cross presented on a black background for 500 ms. Next, participants rated the previously presented picture on valence and arousal (self-paced), with a brief fixation cross (500 ms) separating these ratings. Participants had unlimited time to make these ratings. During the intertrial interval, a white fixation cross was displayed on a black background for 4000-4500 ms. Prior to starting the task, participants completed three practice trials (one for each picture type). The task was presented using Presentation Software (Neurobehavioral Systems Inc., Berkeley, CA). Study procedures were approved by a university Institutional Review Board and in accordance with The Code of Ethics of the World Medical Association for experiments involving humans.

Data Recording and Reduction

Electroencephalography (EEG).

Continuous EEG was recorded using an ActiCap and the ActiChamp amplifier system (Brain Products GmbH, Gilching Germany). The ActiCap contained 32 electrode sites based on the 10/20 system. Electrooculogram data was collected using four electrodes. Two electrodes were placed 1 cm above and below the right eye to measure vertical eye movement. Two electrodes were placed 1cm beside the outer rim of each eye to measure horizontal movement. EEG data was digitized at 24-bit resolution with a sampling rate of 1000 Hz.

EEG data were processed offline using Brain Vision Analyzer 2 software (Brain Products GmBH, Gilching, Germany). Signals from each electrode were re-referenced using the average electrocortical activity of the left and right mastoids (TP9/10) and band-pass filtered using both high (0.01 Hz) and low (30 Hz) pass filters. Each trial was segmented starting 200ms prior to picture onset until picture offset (5000ms). Baseline correction was completed using the 200ms interval prior to picture onset. Corrections for eye blinks and eye movements were made using the approach described by Miller, Gratton and Yee (1988). Artifact analysis was used to identify a voltage step of more than 50.0 μV between sample points, a voltage difference of 300.0 μV within a trial, and a maximum voltage difference of less than 0.50 μV within 100ms intervals. EEG data were also inspected visually for any residual artifacts and data from individual channels with artifacts were rejected on a trial-to-trial basis. The LPP was scored by averaging amplitudes at FC1, FC2, Cz, CP1, and CP2 (Hajcak et al., 2010) between 400-2500ms and 2500-5000ms following picture onset (similar to Hajcak et al., 2007). The electrode pooling was determined using a functional localizer approach (Luck & Gaspelin, 2017), in which affective modulation of the LPP appeared maximal at frontocentral sites. Three participants were excluded from all analyses because of excessive artifacts (< 12 useable trials within each picture type; Moran et al., 2013). Two additional participants were excluded from the LPP analyses because they were identified as outliers (according to Grubb’s test; Grubbs, 1969). This left 118 participants for analyses involving the LPP. We then examined the internal consistency of the LPP. Specifically, we computed even-odd reliability with the Spearman-Brown prophecy formula (r_sb) and found moderate-to-high internal consistency (all ps < .001) for the 400-2500ms LPP (unpleasant: .81; neutral: .69; pleasant: .74) and 2500-5000ms LPP (unpleasant: .76; neutral: .67; pleasant: .78).

Picture Ratings.

Ratings were averaged across trials, separately for each picture type. One participant was excluded from the ratings analyses because they failed to understand the instructions for the picture ratings and an additional two participants were excluded because they were identified as outliers (according to Grubb’s test; Grubbs, 1969). This left 117 participants for analyses involving picture ratings.

Data Analyses

To assess task effects on the LPP and picture ratings, we used a repeated measures analysis of variance (ANOVA) with the factor picture type (pleasant, unpleasant, neutral), performed separately for each dependent variable. Greenhouse-Geisser correction was used for violation of sphericity as needed. Significant main effects were followed up using paired sample t-tests.

To assess associations between TriPM scores, the LPP and picture ratings, we used an analysis of covariance (ANCOVA) with the factor, picture type (pleasant, unpleasant, neutral) and all three triarchic traits entered simultaneously as covariates of interest. Significant interactions were examined using bootstrapped partial correlations and unstandardized residuals representing variance unique to a) unpleasant compared to neutral pictures and b) pleasant compared to neutral pictures. Residualized scores were derived by regressing variables of interest (e.g., LPPs to unpleasant pictures) onto the control variable (i.e., LPPs to neutral pictures) and saving the unstandardized residuals (Meyer et al., 2017). This was done separately for the LPP, valence and arousal ratings. In all subsequent analyses, we use Δ to denote residualized scores controlling for neutral pictures (i.e., ΔLPP to pleasant pictures; ΔLPP to unpleasant pictures; Δvalence to pleasant pictures, Δvalence to unpleasant pictures; Δarousal to unpleasant pictures; Δarousal to pleasant pictures). For the bootstrapped partial correlations, we used 2000 bootstraps and bias corrected accelerated correction to calculate 95% confidence intervals (Westfall, 2011). We interpreted results as meaningful if p < .05 and confidence intervals did not include zero. Analyses were performed using SPSS statistical software version 25.0 and 27.0 (IBM, Armonk, NY).

Results

Table 1 presents means and standard deviations for the LPP and picture ratings.

Table 1 :

Means (SD) for dependent variables

	Unpleasant		Neutral		Pleasant
	M	SD	M	SD	M	SD
Early LPP	8.32	5.48	2.39	4.94	11.20	5.04
Late LPP	8.75	6.74	4.04	7.01	11.42	6.83
Valence	2.55	.92	5.04	.27	6.36	.77
Arousal	4.95	1.91	1.54	.63	3.15	1.39

Note: LPP = late positive potential. Values for LPP reported in μV. LPP split into early (400-2500 ms) and late (2500-5000 ms) time windows.

LPP

400-2500ms

Task Effects.

There was a main effect of picture type [F(2, 234) = 174.65, p < .001, η_p² = .60]. Paired samples t-tests indicated that the LPP was larger for unpleasant [t(117) = 11.49, p < .001] and pleasant [t(117) = 17.89, p < .001] compared to neutral pictures. The LPP was also larger for pleasant compared to unpleasant pictures [t(117) = 6.72, p < .001].

Interactions with Triarchic Traits.

Interactions between picture type and Meanness [F(2, 228) = 1.95, p = .15], Boldness [F(2, 228) = 2.58, p = .08] and Disinhibition [F(2, 228) = 0.22, p = .80] did not reach significance.

2500-5000ms

Task Effects.

There was a main effect of picture type [F(1.90, 222.54) = 70.35, p < .001, η_p² = .38]. Paired samples t-tests indicated that the LPP was larger for unpleasant [t(117) = 7.37, p < .001] and pleasant [t(117) = 10.78, p < .001] compared to neutral pictures. The LPP was also larger for pleasant relative to unpleasant pictures [t(117) = 4.76, p < .001].

Interactions with Triarchic Traits.

There was a significant interaction between picture type X Meanness [F(2, 228) = 3.67, p = .03, η_p²= .03] as well as picture type X Boldness [F(2, 228) = 4.90, p = .01, η_p² = .04]. Follow-up tests showed that Meanness correlated negatively with ΔLPP to both pleasant (r_p = −.25, p = .01, 95% CI [−.41, −.08]) and unpleasant (r_p = −.22, p = .02, 95% CI [−.39, −.04]) pictures.² This association is illustrated in Figure 1, which depicts grand-average waveforms (part A) and scalp distributions (part B) of unpleasant minus neutral pictures and pleasant minus neutral pictures, shown separately for participants with low and high Meanness scores (based on a tercile split, for illustrative purposes only), as well as partial regression plots depicting the association between Meanness and ΔLPP to unpleasant/pleasant pictures (part C).

Figure 1.

A) Grand-average waveforms at a pooling of FC1, FC2, Cz, CP1, CP2 (where the LPP was scored), shown separately for participants with low and high meanness. Low/high meanness groups were created using the top and bottom terciles of meanness scores, for illustrative purposes only. B) Scalp distributions of amplitudes for unpleasant minus neutral pictures and pleasant minus neutral pictures from 2500-5000ms, shown separately for participants with low and high meanness. C) Partial regression plots depict the association between meanness and ΔLPP to unpleasant and pleasant pictures, respectively.

Additionally, Boldness correlated positively with ΔLPP to unpleasant pictures (r_p = .20, p = .03, 95% CI [.02, .37]), but not with ΔLPP to pleasant pictures (r_p = .15, p = .10, 95% CI [−.02, .33]). This is illustrated in Figure 2, which depicts grand-average waveforms (part A) and scalp distributions (part B) of unpleasant minus neutral pictures, shown separately for participants with low and high Boldness scores (based on a tercile split, for illustrative purposes only), as well as partial regression plots depicting the association between Boldness and ΔLPP to unpleasant pictures (part C). The main effect of picture type (p = .70) and the interaction between picture type and Disinhibition (p = .38) did not reach significance.

Figure 2.

A) Grand-average waveforms at a pooling of FC1, FC2, Cz, CP1, CP2 (where the LPP was scored) shown separately for participants with low and high boldness scores. Low/high boldness groups were created using the top and bottom terciles of boldness scores, for illustrative purposes only. Note: positive is plotted downwards, by convention for ERPs. B) Scalp distributions of amplitudes for pleasant minus neutral pictures from 2500-5000ms, C) Partial regression plots depict the association between boldness and ΔLPP to pleasant pictures.

Picture Ratings

Task Effects.

A main effect of picture type for valence ratings [F(1.41, 163.32) = 809.75, p < .001, η² = .88] indicated that participants rated unpleasant pictures as more unpleasant [t(116) = 28.61, p < .001] and pleasant pictures as more pleasant compared to neutral pictures [t(116) = 18.51, p < .001]; pleasant pictures were also rated as more pleasant then unpleasant pictures [t(116) = 31.04, p < .001]. A main effect of picture type for arousal ratings [F1.692, 196.26) = 219.53, p < .001, η² = .65] indicated that participants rated unpleasant pictures [t(116) = 19.27, p < .001] and pleasant pictures [t(116) = 13.04, p < .001] as more arousing than neutral pictures. Participants also rated unpleasant pictures as more arousing than pleasant pictures [t(116) = 9.91, p < .001].

Interactions with Triarchic Traits.

For valence ratings, there was a significant interaction between picture type X Meanness [F(1.35, 151.98) = 7.96, p < .001, η_p² = .07], but not Boldness (p = .40) or Disinhibition (p = .76). Follow-up tests showed that Meanness was unrelated to Δvalence ratings of pleasant pictures (r_p = .09, p = .35, 95% CI [−.09, .28]), but positively related to Δvalence ratings of unpleasant pictures (r_p = .41, p < .001, 95% CI [.24, .54]). Thus, individuals higher in Meanness rated unpleasant pictures as more pleasant compared to individuals lower in Meanness, as depicted in Figure 3A.

Figure 3.

A) Partial regression plot depicting the association between meanness and Δvalence to unpleasant pictures. Greater values indicate more pleasant valence. B) Partial regression plot depicting the association between meanness and Δarousal to unpleasant pictures. Greater values indicate greater arousal.

For arousal ratings, there was a significant interaction between picture type X Meanness [F(.77, 199.74) = 9.52, p < .001, η_p² = .08], but not Boldness (p = .23) or Disinhibition (p = .40). Follow-up tests showed that Meanness was unrelated to Δarousal ratings of pleasant pictures (r_p = .10, p = .29, 95% CI [−.09, .30]), but was negatively related to Δarousal ratings of unpleasant pictures (r_p = −.25, p = .01, 95% CI [−.43, −.07]). Thus, individuals higher in Meanness rated unpleasant pictures as less arousing, as depicted in Figure 3B.

Discussion

This study used a passive picture viewing paradigm to investigate the relationship between the triarchic traits and neural and self-reported measures of emotional processing in young adults. Individuals with higher meanness showed smaller LPPs to both unpleasant and pleasant images rated unpleasant pictures as less arousing and more pleasant. In contrast, individuals with higher boldness showed larger LPPs to unpleasant images, with no association observed for the LPP to pleasant images or ratings. No associations were observed for disinhibition.

The Roles of Meanness and Boldness in Emotional Processing

Prior work had shown that compared to non-psychopathic individuals, psychopathic individuals are characterized by blunted psychophysiological response to unpleasant pictures (e.g., Vallet et al., 2020). Here, results build on this work to suggest that in an undergraduate sample, individual differences in meanness are similarly associated with reduced electrocortical processing of unpleasant images. Therefore, blunted response to unpleasant stimuli among psychopathic individuals may be a function of the triarchic trait of meanness. Moreover, our results indicate that meanness is associated with reduced response to unpleasant pictures in general. Additionally, in contrast to some prior categorical work, electrocortical and subjective responses to unpleasant pictures were concordant (i.e., individuals higher in meanness also rated unpleasant pictures as more pleasant and less arousing). Although the current study does not elucidate the precise mechanism behind blunted response to unpleasant stimuli among individuals higher in meanness, associations were only observed in the late time window of the LPP, suggesting that disengagement/reductions in sustained attention, rather than reduced initial attention to emotional pictures may drive lower reactivity to emotional images observed among individuals higher in meanness. Along these lines, boldness was also only associated with the LPP in the late time window, suggesting greater elaborative processing of unpleasant pictures rather than differences in early stimulus processing among individuals with higher versus lower boldness.

In contrast to prior work, which found that categorical psychopathy was related to blunted psychophysiological response to unpleasant but not pleasant pictures, results observed here suggest that meanness, which may more precisely capture the core deficit underlying affective response in psychopathy (i.e., similar to the “affective factor”; Patrick, 2022), may be associated with deficits in empathic and affiliative emotional response. Therefore, results suggest that meanness may account for more than one phenomenon in psychopathy, namely, reduced meaningful emotional attachment to others and reduced threat responsivity. Researchers have argued that low communion (i.e., disinterest in interpersonal closeness) is a deficit central to psychopathy (Sherman & Lynam, 2017). Here, evidence of abnormal processing of affiliative stimuli among participants higher in meanness suggests one potential mechanism for this disinterest. Moreover, our results suggest, more broadly, that meanness might reflect a general deficiency in the sustained processing of emotional stimuli. Nonetheless, because the stimuli used here depicted generic and varied content, future work is needed to determine whether a different response to unpleasant and pleasant stimuli might be observed for specific picture content. For example, individuals higher in meanness if stimuli might show more normative response to pleasant stimuli if these stimuli depicted content that was more directly related to egocentric pleasure or goals/drives (e.g., erotic stimuli; pictures of food or alcohol), rather than, for example, affiliative scenes.

In contrast to the results observed for meanness, greater boldness was related to larger LPPs to unpleasant pictures (and was unrelated to the LPP elicited by pleasant pictures). The triarchic model posits that individuals higher in boldness should generally be characterized by diminished physiological response to threatening stimuli (Patrick et al., 2009). In line with this notion, individuals who were more bold showed smaller LPPs to unpleasant pictures in an emotion regulation task (Ellis et al., 2017), although Perkins and colleagues (2022) did not replicate this effect. Similarly, Esteller and colleagues (2016) found that individuals who were more bold showed a smaller startle response to threatening pictures. Differences in the type of paradigm used and the level of response being assessed in prior work may go some way toward explaining differences between results. For example, smaller LPPs in the context of emotion regulation tasks seem functional/adaptive and might therefore indicate more responsivity to task context among individuals with higher self-reported boldness. Another potential explanation for contradictory and null findings (e.g., Perkins et al., 2022) could be reliance on unitary indicators of boldness, when it may in fact be a multidimensional construct (Patrick et al., 2019). That is, Patrick and colleagues (2019) conducted a bifactor analysis of a more expansive 130-item measure of boldness and identified an underlying boldness dimension along with lower-order secondary factors of emotional stability and venturesomeness. With larger samples and more refined measures of boldness, future research may be able to link specific aspects of this construct to emotional processing, potentially resolving inconsistencies in the literature.

Although our finding that boldness was associated with larger LPPs to unpleasant pictures is inconsistent with some prior work in the psychopathy literature, it is in line with a broader literature on normative personality traits and internalizing psychopathology. Specifically, boldness has been described as reflecting stress immunity, low anxiety, and social dominance (Patrick et al., 2009; Patrick et al., 2022). On the other hand, individuals low in boldness are low in extraversion (Patrick & Drislane, 2015; Sleep et al., 2019³) and tend to be high in internalizing psychopathology, particularly anxiety (Latzman et al., 2019). Consistent with our finding that individuals low in boldness have smaller LPPs, individuals who are less extroverted also have a smaller LPPs to unpleasant pictures (Speed et al., 2015). In addition, both depression (Bauer & MacNamara, 2021; MacNamara et al., 2016) and diffuse and severe anxiety have been linked to blunted LPPs to unpleasant pictures (Bauer et al., 2023). Situating boldness within the broader psychopathological literature is consistent with theorizing that boldness is a manifestation of low threat sensitivity (fearlessness) – a biobehavioral trait that confers risk for internalizing psychopathology at low levels and manifests as low anxiety and social dominance at high levels (Latzman et al., 2020; Patrick et al., 2009; Patrick, 2022; Perkins et al., 2022). As such, our findings expand understanding of boldness, to suggest that – in opposition to or in contrast to internalizing psychopathology and introversion - it is associated with increased engagement with salient external stimuli. More broadly, our results provide a connection between the triarchic traits and other psychopathological spectra, consistent with increasing evidence in favor of a more unified model of psychopathology (e.g., HiTOP; Kotov et al., 2017; Kotov et al., 2021).

A spectrum-based approach to psychopathology is complementary to a multilevel perspective, in which psychopathological mechanisms are also understood as they manifest across various levels of response (e.g., Insel et al., 2010). Here, we found that meanness was related to both reduced psychophysiological and subjective response to unpleasant pictures (though meanness was only associated with reduced LPPs to pleasant stimuli and not to subjective ratings of these pictures). Therefore, individuals with higher self-reported meanness did not appear motivated to disguise their apparent lack of engagement with unpleasant stimuli. On the other hand, boldness was only associated with larger LPPs to unpleasant pictures and not subjective response to these stimuli. These results are in line with findings from our group and others showing that individuals who are high in anxiety or depression - and therefore probably low in boldness - are characterized by reduced psychophysiological response to unpleasant stimuli, but do not show this effect for subjective ratings (Bauer et al., 2023; Cuthbert et al., 2003; McTeague & Lang, 2012). Therefore, meanness (for pleasant stimuli) and boldness (for unpleasant stimuli) might be associated with abnormalities in neurobiological response that are discordant with subjective response. This discordance could be explained by willful misrepresentation or poor insight/misinterpretation of internal states, in line with the notion that severe psychopathology and personality disorders may be characterized by difficulties with self-awareness (APA, 2013).

Though our results are informative about both meanness and boldness, we failed to observe significant associations involving disinhibition. This is consistent with null results observed for disinhibition in the context of an emotion regulation task (Ellis et al., 2017) and with other kinds of emotional stimuli (e.g., interpersonal aggression, van Dongen et al., 2018). Nonetheless, recent work found a weak association between disinhibition and reduced affective modulation of the LPP to emotional (unpleasant, pleasant) images when participants were instructed to attend to the emotional content of images but not when asked to attend to non-emotional content (Ribes-Guardiola et al., 2022). However, this association did not remain after controlling for the contribution of other triarchic traits (Ribes-Guardiola et al., 2022). As participants in the current study were allowed to allocate attention as they pleased, null associations with disinhibition might be explained by variation in where participants allocated attention, which could have weakened effects.

Limitations and Future Directions

A limitation of the current study was our failure to include startle, which restricted our ability to draw comparisons with some prior work on affective response in psychopathy. Additionally, our sample was recruited from a university in the southern USA, and our results may not generalize to samples from other areas in the world or with a different demographic composition. This point is underscored by findings that the classic deficient startle response of the psychopath (Patrick, 1994; Patrick et al., 1993) did not replicate in a large sample of African American offenders (Baskin-Sommers et al., 2011). Future research should clearly articulate how culture and identity may alter the relationship between psychopathy and physiological indicators of emotional processing. Additional studies should also determine the specificity of these relationships to stimuli of varying picture content. For example, boldness may relate more strongly to unpleasant scenes depicting threat, rather than more general unpleasant content. This would be in keeping with results from Vaidyanathan and colleagues (2009), who found that a positive association between fearfulness (i.e., low boldness) and startle eyeblink was largest for negatively valenced stimuli depicting threat relative to other kinds of unpleasant stimuli. This pattern would be in line with theory that situates boldness as a manifestation of an underlying deficiency in acute threat detection, rather than a general deficiency in processing negatively valenced stimuli (Patrick et al., 2009; Patrick, 2022). Along similar lines, the association between meanness and of the LPP to pleasant stimuli observed here might be dependent on affiliative picture content.

Future research may also wish to use physiological measures to help explain variance in clinical outcomes. For example, researchers could examine how variation in the LPP to emotional images across time corresponds to changes in psychopathic traits, particularly meanness. That is, smaller LPPs to emotional pictures could potentially help explain variance in behavioral outcomes, such continuity/discontinuity from bullying in adolescence (Baroncelli et al., 2022) to antisocial behavior in adulthood (Gray et al., 2022). Similarly, future research could examine whether the LPP might moderate attention retraining to target the interpersonal and affective deficits characteristic of psychopathy (Baskin-Sommers et al., 2015).

Conclusions

The current results validate the triarchic traits as relevant modulators of electrocortical and subjective response to emotional pictures. Although our results for meanness are in line with the predictions of the triarchic model and fit with the overarching notion of psychopathy as a disorder of callousness and low empathy, our findings for boldness stand in contrast to the model’s predictions and differ from prior work in this area. However, the broader literature on internalizing psychopathology and extraversion support the findings observed here. As such, we identify potential neurobiological links between psychopathy and other forms of psychopathology, but also call upon the triarchic model to align predicted associations for boldness with this broader literature. Psychophysiological research on psychopathy tends to study psychopathy exclusively despite the well-documented relationship between psychopathy and other forms of psychopathology (Latzman et al., 2020; Lilienfeld, 2018). Going forward, continued examination of affective response as it relates to transdiagnostic traits relevant to the entire spectrum of psychopathology may lead to a more precise understanding of distinctions and overlap between psychopathic traits and other psychiatric constructs/disorders, while also advancing a more fine-grained conceptualization of psychopathy and the neurobiological correlates of psychopathic traits among young adults.