the superior auricular reflex results deserve further...

RESPONSE MODULATION, PSYCHOPATHY, AND ERPS S1

Supplementary Materials

Distribution of Fearless Dominance and Impulsive Antisociality Scores

Because participants were only selected based on either their Fearless Dominance (FD) or

Impulsive Antisociality (IA) score and not both, the score on the factor for which they were not

selected was free to vary. This resulted in an approximately normal distribution of FD and IA

scores (See Figures S1 and S2, respectively; |skewness| < 0.25, |kurtosis| < 0.72). Additionally,

the Triarchic Psychopathy Measure (Patrick, Fowles, & Krueger, 2009; Patrick, 2010) was

administered during the laboratory session as a measure of psychopathy separate from the MPQ

estimated scores. FD and IA correlated in the expected ways with Triarchic scores indicating that

they were accurately estimated by the MPQ and adequately represented in our sample (see Table

S1). Table S1 also provides test-retest correlations between the screening and laboratory sessions

for FD and IA.

Participant Exclusion

Participants who were excluded because of bad performance did not differ in their levels

of fearless dominance (FD), t(76) = -0.45, p = .657, or impulsive antisociality (IA), t(76) = 0.18,

p = .860, from participants who were included in this study. The mean fearless dominance score

was -0.14 (SD = 0.79) for included participants and -0.02 (SD = 0.90) for excluded participants.

The mean impulsive antisociality score was -.18 (SD = 0.71) for included participants and -0.22

(SD = 0.70) for excluded participants.

ERN and N1 Peaks

As shown in Figures S3 and S4, ERNs in all conditions were maximal at FZ, as was the

N1 to the stop signal. The N1 distribution in this study was consistent with previous literature

(Näätänen & Picton, 1987). Although the ERN is traditionally reported at FCz, EEG was not


recorded from this site because of equipment limitations. However, the ERN has been reported

previously at FZ (Hajcak, Moser, Yeung, & Simons, 2005; Hajcak & Simons, 2008) with similar

properties as those observed in this study. Table S2 gives the means and standard deviations for

these components.

Relationships between IA, Behavioral Performance, ERPs, and Gender

Because our sample was 56% women, correlations were computed between IA,

behavioral performance measures, ERPs and gender. Only the ERN following correct lexical

decisions was correlated with gender at a trend level, r(65) = .24, p = .052. No significant

correlations were observed between gender, IA, behavioral measures, or any other ERPs, |rs|

< .17, ps > .16. Additionally, correlations between IA, behavioral performance and ERPs did not

significantly differ for men and women, |Fisher's Zs| < 1.43, ps > .15, showing a similar pattern

to the sample as a whole.

Participant Engagement

As shown in Table S3, correlations were computed between participants' reported level of

engagement in the task (from the post-task questionnaire), IA, behavioral measures, and ERPs;

these correlations are given in Table S1. Participants' overall level of engagement was

significantly related to LD accuracy and ERN following SS errors and was related to SS N1 at a

trend level, indicating that participants who were more engaged in the task performed better

overall and processed SS errors to a greater extent. How hard participants tried to respond word

or non-word correctly was also significantly related to LD accuracy. Overall engagement and

how hard participants tried to respond word or non-word correctly were only related to IA at a

trend level. No measure of engagement was significantly related to FD, RT, SSD, or SSRT.

Lexical Decision Stop Signal (LDSS) Task Characteristics


Although the lexical decision component of the LDSS task used in the current study

increased the complexity of the go task over more traditional letter discriminations (X vs. O), the

mean SSRTs found here did not differ significantly from those found by Wodushek and

Neumann (2003) in a sample of adults with ADHD, t(109) = 1.31, p = .19. Our high IA group

did not differ significantly from their high ADHD symptom group, t(54) = 1.17, p = .25, and our

low IA group did not differ significantly from their low ADHD symptom group, t(53) = 0.69, p =

.49. This indicates that the increased complexity of the go task did not have a significant effect

on the stopping process. Additionally, neither lexical status nor word valence significantly

influenced the relationship between IA and any behavioral or ERP measure (Heritage &

Benning, 2012). For example, across pleasant, neutral, aversive, and non-words, correlations

between IA and lexical decision accuracy ranged from -.21 to -.26. The same range of

correlations between IA and SSRTs in various conditions was -.29 to -.34.

ERP-IA Relationships Controlling for Behavioral Performance

Partial correlations were computed between IA and all reported ERP measures

controlling for LD accuracy and SS accuracy to determine if behavioral performance influenced

these relationships. IA remained significantly correlated with ERN amplitude following incorrect

LD, r(64) = .27, p = .030, and correct LD, r(64) = .26, p = .041, but not SS errors, r(64) = .15, p

= .225. IA also remained significantly correlated with SS N1, r(64) = .27, p = .031.

Prediction of Each ERN Amplitude from Other ERNs

To generate new variables that represented the unique variance associated with each

ERN, separate linear regressions were conducted with each ERN as the dependant variable and

the other two as predictors. The unstandardized residuals were saved from these analyses as a

measure of the unique variance in each ERN not accounted for by the other two ERNs. These


residuals were then subjected to the meditational analyses displayed in the bottom half of Table

3. As displayed in Table S4, the SS error ERN significantly predicted each LD ERN, and the two

LD ERNs independently predicted SS ERN. IA was no longer significantly correlated with the

unique variance associated with incorrect, correct LD, or SS errors. FD was still not correlated

with any ERN amplitude.

However, it is still possible that despite a lack of a significant correlation between IA and

residualized ERNs, SS N1 amplitude may yet mediate the IA → ERN relationship (Kenny,

Kashy, & Bolger, 1998) because IA and ERN relate to the N1 in opposite ways. Consider that

the relationship between IA and ERN is such that higher scores on IA produce shallower ERN

amplitudes, but the relationship between N1 and ERN is such that larger N1 amplitude is

associated with larger ERN amplitude. In this case, though both paths involving the N1 are

significant, they are opposite in sign, and thus the path between IA and ERN may be non-

significant. This situation gives rise to what MacKinnon, Fairchild, and Fritz (2007) call

inconsistent mediation, as the mediator (in this case, N1 amplitude) acts as a suppressor variable

on the IA → ERN relationship.

As shown in Table S5, only the residualized SS ERN correlated with the SS N1, which

allowed N1 amplitude to mediate the IA → SS ERN relationship, as shown in Table 3. Because

the residualized LD ERNs were not related to SS N1 amplitude, they would not be able to

mediate the IA → LD ERN relationships in the analyses reported in Table 3.


References

Hajcak, G., Moser, J. S., Yeung, N., & Simons, R. F. (2005). On the ERN and the significance of

errors. Psychophysiology, 42(2), 151–160. doi:10.1111/j.1469-8986.2005.00270.x

Hajcak, G., & Simons, R. F. (2008). Oops!.. I did it again: An ERP and behavioral study of

double-errors. Brain and Cognition, 68(1), 15–21. doi:10.1016/j.bandc.2008.02.118

Heritage, A. J., & Benning, S. D. (2012). Stimulus processing and psychopathy in a lexical

decision - stop signal task. Manuscript in preparation.

Kenny, D. A., Kashy, D., & Bolger, N. (1998). Data analysis in social psychology. In D. Gilbert,

S. Fiske, and G. Lindzey (Eds.), Handbook of social psychology (4th ed., pp. 233-265).

New York: McGraw-Hill.

MacKinnon, D. P., Fairchild, A. J., & Fritz, M. S. (2007). Mediation analysis. Annual Review of

Psychology, 58, 593-614.

Näätänen, R., & Picton, T. W. (1987). The N1 wave of the human electric and magnetic response

to sound: A review and an analysis of the component structure. Psychophysiology, 24(4),

375-425.

Patrick, C. J. (2010). Triarchic psychopathy measure (TriPM). Retrieved from

https://www.phenxtoolkit.org/index.php?pageLink_browse.protocoldetails&id_121601

Patrick, C. J., Fowles, D. C., & Krueger, R. F. (2009). Triarchic conceptualization of

psychopathy: Developmental origins of disinhibition, boldness, and meanness.

Development and Psychopathology, 21(3), 913–938. doi:10.1017/S0954579409000492

Wodushek, T. R., & Neumann, C. S. (2003). Inhibitory capacity in adults with symptoms of

attention deficit/hyperactivity disorder (ADHD). Archives of Clinical Neuropsychology.

Vol 18(3), 317–330.


Table S1

Correlations among Fearless Dominance, Impulsive Antisociality and Triarchic Psychopathy Measure Subscales

FD Lab IA Lab Boldness Meanness DisinhibitionFD Screen (.92**) -.17 - - -IA Screen -.12 (.83**) - - -Boldness .78** -.25 1 - -Meanness .10 .44** .13 1

Disinhibition -.46** .52** -.41** .27* 1

Note. * p < .05, ** p < .01. FD = fearless dominance, IA = impulsive antisociality. Correlations in parentheses represent test-retest

correlations between FD and IA obtained at screening and test. The Triarchic Psychopathy Measure (Patrick, 2010) was only

administered in the laboratory.


Table S2

Means (And Standard Deviations) for ERP Measures in the Sample as a Whole and by Median Split on Impulsive Antisociality

Group SS N1 Incorrect LD ERN Correct LD ERN SS Error ERN

Whole Sample

-14.1 (6.59) -6.15 (5.26) -2.95 (2.37) -7.16 (3.70)

Low IA -16.2 (6.77) -6.88 (5.88) -3.48 (2.46) -7.99 (3.30)

High IA -12.0 (5.76) -5.42 (4.53) -2.42 (2.18) -6.34 (3.93)

Note. SS = stop signal, LD = lexical decision. All values are peak amplitude measured in microvolts.


Table S3

Correlations between Task Engagement and Fearless Dominance, Impulsive Antisociality, Behavioral Measures, and ERP Responses

Question Behavioral Measures ERP ResponsesFD IA RT LD

AccuracySS

AccuracySS

DelaySSRT Incorrect LD

ERNCorrect

LD ERNSS Error

ERNSS N1

Overall Engagement

.13 -.21+ -.03 .37** .09 .05 -.11 -.15 -.06 -.25* -.22+

Task Importance

.09 -.16 .11 .21+ -.08 .07 .00 .10 .01 -.06 -.02

LD Effort -.18 -.22+ -.11 .46** .02 -.04 -.05 -.12 .08 .00 -.01SS Effort -.10 -.14 .09 .14 .11 .05 .01 -.07 .05 .05 -.03

Note. * p < .05, ** p < .01. LD = lexical decision, FD = fearless dominance, IA = impulsive antisociality, RT = reaction time, SS =

stop signal, SSRT = stop signal reaction time. Overall Engagement = “How engaged were you in this task?” Task Importance = “How

important did you think this task was?” LD Effort = “How hard did you try to respond word or non-word correctly?” SS Effort =

“How hard did you try to avoid making a mistake like responding when you shouldn't have?”


Table S4

Summary of Regression Analysis Predicting ERN Amplitudes

Independent Variable B SE(B) β t P

Incorrect LD ERNCorrect LD ERN .262 .278 .120 .942 .349SS Error ERN .517 .176 .374 2.93 .005

Correct LD ERNIncorrect LD ERN .049 .051 .106 .942 .349SS Error ERN .312 .071 .492 4.39 .000

SS Error ERNIncorrect LD ERN .214 .073 .296 2.93 .005Correct LD ERN .699 .159 .444 4.39 .000

Note. LD = lexical decision, SS = stop signal. Unstandardized residuals from these analyses were used in mediation analyses as

indicators of the unique variance associated with each ERN.


Table S5

Correlations among Fearless Dominance (FD), Impulsive Antisociality (IA), and the Unique Variance of Each ERN

Incorrect LD ERN Correct LD ERN SS Error ERNFD .01 .13 -.11IA .17 .15 .10SS N1 .01 .13 .49**

Note. LD = lexical decision, SS = stop signal. ** p < .01.


Figure S1. Histogram of fearless dominance scores obtained in the laboratory for the sample as a whole.


Figure S2. Histogram of impulsive antisociality scores obtained in the laboratory for the sample as a whole.


Figure S3. Grand average waveforms of the ERN following incorrect lexical decisions, correct lexical decisions and SS errors for the

sample as a whole shown here at all electrodes used.


Figure S4. Grand average waveforms of the N1 following SS onset for the sample as a whole shown here at all electrodes used.

the superior auricular reflex results deserve further...

Documents