A Research on Reduced Fear in Psychopathy

Abstract

This paper analyzes three published articles pertaining to research conducted on the functional impairment of reduced fear in those with psychopathy, a multidimensional construct characterized by emotional deficits and an increased risk of antisocial behaviors. These articles, however, vary in their methods of studying reduced fear in psychopathy. A study by Levenston, Patrick, Bradley, and Lang (2000) explored both the abnormal attentional and emotional modulations of affect-startle in psychopathy by examining blink potentiation in response to pleasant, unpleasant, and neutral images. Another study, by Birbaumer, Veit, Lotze, Erb, Hermann, Grodd, and Flor (2005), studied the efficacy of fear conditioning in those with psychopathy, while using measures of skin conductance (SCR), self-report (valence, arousal), and functional magnetic resonance imaging (fMRI). Lastly, a study by Marsh, Finger, Mitchell, Reid, Sims, Kosson, Towbin, Leibenluft, Pine, and Blair (2008) examined the reactivity to fearful faces in those with psychopathy by analyzing their amygdala activation in emotional facial expression processing using functional magnetic resonance imaging (fMRI). Even though these studies varied in their methods of studying reduced fear in psychopathy, they all found significant evidence to support a relationship between this particular physiological factor and the psychological disorder of psychopathy.

Introduction

Countless studies have been conducted on various features of psychopathy, focusing on the neurobiological factors and functional impairments associated with the disorder. Said studies have been conducted primarily to address the inquiries pertaining to what actually makes someone a “psychopath”; what impairments and/or abnormalities do those with psychopathy have compared to those who do not have the disorder? One such impairment seen in those with psychopathy is that of reduced fear. This observation brought about new inquiries pertaining to psychopathy, which then led to a surge of additional research studies. One important research question for these studies was: Is experiencing the functional impairment of reduced fear a key component of what makes someone a “psychopath”? Several studies, three of which are discussed in this paper, have concluded that there is significant evidence supporting a relationship between reduced fear and psychopathy. The three studies mentioned throughout this paper took different approaches to study the effect(s) psychopathy has on one’s ability to identify and experience fear and, even so, concluded with similar results. This paper examines the studies of Levenston, Patrick, Bradley, and Lang (2000), Birbaumer, Veit, Lotze, Erb, Hermann, Grodd, and Flor (2005), and Marsh, Finger, Mitchell, Reid, Sims, Kosson, Towbin, Leibenluft, Pine, and Blair (2008), in an attempt to gain a better understanding of what those with psychopathy experience when attempting to identify and experience fear in comparison to those who do not have psychopathy.

Literature Review

In Levenston et. al. 's (2000) study, the correspondence amongst abnormal modulation of affect-startle and psychopathy was explored. The participants within this study included thirty-six male inmates- eighteen with psychopathy, defined by the Hare Psychopathy Checklist- Revised, and eighteen without psychopathy. Said participants observed specific categories of pleasant (eortic or thrilling) and unpleasant (victim or direct threat) photographic slides, along with neutral images. Patterns of startle modulation were analyzed in both those with and without psychopathy by measuring blink potentiation, a type of defensive mechanism. An increase in blink potentiation indicated higher levels of negative and aversive effects associated with the image being displayed. In response to noise probes, blink potentiation was measured at 300 milliseconds, 800 milliseconds, and later times (1,800, 3,000, and 4,500 milliseconds) after a photographic slide was displayed. Blink potentiation measured at 300 milliseconds evaluated attentional modulations, while blink potentiation measured at 800 milliseconds or later evaluated emotional modulations. Attentional modulations were indicators of the participants’ awareness of the stimuli, while emotional modulations were indicators of the participants’ feelings towards the stimuli. As shown in Appendix A, in attentional modulation of startle (300 milliseconds), it was found that those without psychopathy displayed attentional inhibition of startle reflex for both pleasant and unpleasant images but a startle potentiation when viewing neutral images. Those with psychopathy, on the other hand, displayed an inhibitory effect of attention on startle reflex when viewing pleasant and neutral images but a startle potentiation when viewing unpleasant images. Also shown in Appendix A, in emotional modulation of startle (800 or more milliseconds), those without psychopathy displayed startle potentiation when viewing unpleasant images, while those with psychopathy displayed startle inhibition when viewing the same unpleasant images. The initial startle potentiation noted in those with psychopathy was thought to be linked to the unpleasant images being more motivationally significant to those with psychopathy than to those without psychopathy. Due to the unpleasant images having more motivational significance, those with psychopathy were more engaged with the images at first (attentional modulation)- causing the potentiation- and, thus, were less startled by them at later times (emotional modulation). These results, therefore, indicated a heightened aversion threshold and a weakness in initial stimulus evaluation among those with psychopath.

Another study conducted by Birbaumer et al. (2005) sought out to explore the correlation between psychopathy and fear conditioning. The participants within this study were ten male criminal offenders on bail who had psychopathy, defined by the Hare Psychopathy Checklist- Revised, and ten healthy male controls. This study used pavlovian conditioning, in which the conditioned stimulus was images of neutral faces and the unconditioned stimulus was a painful pressure administered after viewing the same images of neutral faces. The neutral faces would then, consequently, become associated with the experienced pain and no longer be perceived as “neutral”. The participants' skin conductance responses, self-reports of emotional valence, arousal, and contingency, and fMRIs of their brain were used as measures throughout this study. Through fMRI, it was found that healthy controls showed enhanced differential activation in the limbic-prefrontal circuit during the acquisition of fear and, through SCR and self-reports, successful conditioning for valence and skin conductance responses. Conversely, those with psychopathy showed no significant activity in the limbic-prefrontal circuit during the acquisition of fear and failed to show condition skin conductance and emotional valence ratings (Birbaumer, et al., 2005, p. 799). Both those with and without psychopathy, however, displayed a conditioned response for arousal and contingency ratings and were able to clearly differentiate between the conditioned and unconditioned stimuli. Even so, those with psychopathy were unable to form a fear connection between the two stimuli. Thus, it was concluded that the dissociation of emotional and cognitive processing may be the neural basis of the lack of anticipation of aversive events in those with psychopathy.

Lastly, a study by Marsh et al. (2008) evaluated the amygdala and its role both in the acquisition and expression of conditioned fear and in the perception and recognition of others’ fear. This study considered how fearful faces, as well as vocal and postural expressions, are interpreted by those with and without psychopathy, while focusing on the role of the amygdala. Participants in this study included thirty-six children and adolescents between the ages of ten and seventeen-years-old; twelve of which had callous-unemotional traits with either conduct disorder or oppositional defiant disorder, another twelve had ADHD, and the remaining twelve were healthy comparison controls. Those in the callous-unemotional group were screened to have scores greater than or equal to twenty on the Antisocial Process Screening Device and the Psychopathy Checklist - Youth Version. Those in the ADHD and comparison groups could not have scores equal to or greater than twenty on these diagnostic evaluations. While the processing of fearful facial expressions occured, fMRI was used to evaluate patterns of amygdala activation, and responses and latencies of each participant were recorded throughout four trials. Participants were presented with images of emotional expressions of ten men and women from the Pictures of Facial Affect series, their expressions being either neutral, fearful, or angry with varying intensities, and were asked to identify the emotion being expressed. The behavioral data results indicated a main effect of emotional expression on accuracy; accuracy was greater for neutral facial expressions than for angry facial expressions. No effect of emotional expression was observed for reaction times; all three groups were able to respond to stimuli with relatively similar times. Those in the comparison and ADHD groups showed significantly greater responses to fearful expressions compared to neutral expressions, while those in the callous-unemotional group did not. The fMRI results, shown in Appendix B, indicated that those in the callous-unemotional group had significantly lower amygdala activation in response to fearful facial expressions, compared to the comparison and ADHD groups, while processing the fearful facial expressions. Furthermore, specifically between the amygdala and ventromedial prefrontal cortex, analysis of functional connectivity demonstrated greater correlation in the comparison and ADHD groups than in those in the callous-unemotional group. These findings further validate the idea that the personality traits of callousness and unemotionality- prevalent in those with psychopathy - are affiliated with the reduction of response to distress-based social cues in the amygdala.

Conclusion

Those without psychopathy are typically able to identify and experience fear naturally. Levenston et al.’s study demonstrated that those with psychopathy experience startle inhibition in response to viewing unpleasant, fear-provoking images, whereas those without psychopathy experience startle potentiation. Birbaumer, et al.’s study denoted that those with psychopathy, although able to distinguish between conditioned and unconditioned stimuli, are unable to establish fear connections in pavlovian conditioning, whereas those without psychopathy are able to. Marsh et al.’s study displayed that those with psychopathy experience decreased activation in the amygdala, which plays an essential role in recognition of fear, when processing images of fearful faces, whereas those without psychopathy do not. Based on the findings of these three studies, it is clear that those with psychopathy have impairments in identifying and experiencing fear, especially compared to those who do not have psychopathy. Therefore, it may be reasonable to assume that reduced fear is a key component of what truly makes someone a “psychopath”.