Emotional Deficit in Patients with Psychopathy: a Literature Review

Psychopathy is a form of severe personality disorder (APA, 2013; Blair et al., 2004). Dean and colleagues (2013) indicate that psychopathy is divided into two subgroups. Primary psychopathy (factor 1) is characterised by an emotional detachment which manifests in callousness and poor empathy. Secondary psychopathy (factor 2) is characterised by shallow affect and significant dysfunction in regulation of emotions leading to impulsive antisocial behaviour. Although psychopaths are regarded as cognitively whole, atypical responses to emotional material is deemed their most dominant trait. The Hare Psychopathy Checklist-Revised has been defined as the “gold standard” clinical evaluation of psychopathy (Fulero, 1995; Acheson, 2005, cited in Archer and Wheeler, 2013), with lack of empathy being included as one of many assessed characteristics. A large body of evidence suggests that individuals with psychopathy have a deficit in processing emotional material, which is considered to be the heart of psychopathy. There are countless methods used to measure emotional deficits in psychopathy such as, fear potentiated startle (FPS), recognition of facial emotions, pupillometry and emotional distraction tasks, to name a few. However, this evidence is inconsistent and contradictory. This essay will therefore critically explore the empirical evidence base of two important measures; FPS and recognition of facial expressions. 

Blair et al. (2004) explored the ability of incarcerated males to recognise and misidentify emotional facial expressions. This experiment consisted of 2 (groups: psychopathic individuals scoring 30 or above on the PCL-R (n = 19), compared with non-psychopath’s (n = 19) scoring less than 20)x 6 (expressions: happy, surprised, disgust, angry, sad, fearful) mixed-model factorial design. Using this type of design is advantageous because quality examination of the interaction between independent and dependent variables can be conducted. Participants age and intelligence scores were obtained from the Raven’s Advanced Matrix-Set I (Raven, 1965). However, no significant group difference between age or Raven’s scores were present. This is advantageous because this provides information about a specific subgroup with these demographic variables. Emotions were presented using a 21-picture successive graded hierarchy. Supporting the low-fear positions and violence inhibition mechanism (VIM; Blair, 1995) hypotheses, it was predicted that psychopaths would experience difficulty in recognising fearful and sad expressions. Results found that psychopathic individuals had a selective deficit for identification of fearful expressions with an effect size of 4.68 compared to 7.87 for non-psychopaths. This also seemed apparent in the number of errors made when detecting fearful expressions (effect size of 0.84: psychopath’s; 0.21: non-psychopaths). Interestingly, an effect size of 0.47 for both groups indicate no group difference in identification of sad expressions. Nevertheless, it should be noted that in addition to fear, psychopathic individuals performed insufficiently compared to non-psychopaths for all emotions (e.g., effect size for happy; 11.05: psychopaths; 12.70: non-psychopaths). Critically, this shows only a moderate group difference in effect sizes. This may be due to poor statistical power. Power represents the likelihood that a study will detect an effect and a small sample size (n = 19) prevents power functioning to its full potential. In conscience, 200 males were initially selected for participation but due to rigours assessment (e.g., psychiatric files screened for evidence of psychopathy, exclusion of brain injury individuals), 19 psychopathic males were diligently selected. Furthermore, high inter-rater reliability total coefficient scores (higher than 0.83), alpha coefficients and inter-item correlations highlights the superiority of the PCL-R as a consistent scale which functions in a unitary design (Hare, 1991; Blair, 2004). In support, research has found that both psychopathic adults and children displayed significantly reduced impairment whilst identifying sad and fearful expressions. However, these studies used various psychopathy screening measures such as, the Minnesota Multiphasic Personality Inventory, Psychopathy Screening Device and the Activity Preference Questionnaire to classify participants. These measures might not act in unity in that they all fail to capture simultaneous characteristics. Concurrently, the PCL-R is the “gold standard” measurement of psychopathy (Fulero, 1995), and thus is the most reliable (Hare, 1991). In addition, such studies recruited larger sample sizes, the highest being 132 subjects, producing increased internal and external validity and substantiated statistical power. 

Hastings, Tangney, and Stuewig (2008) conducted further analyses with a large sample of 154 incarcerated males with pictures at 60% and 100% intensity levels. Findings show an overall difficulty to identify presented emotions at both intensity levels with specific impairments in recognising happy and sad expressions. Evidently, there are contradictions due to conflicting findings regarding impairments in emotional processing toward different emotional expressions. In reiteration, Brook et al. (2013) conducted a literature review of 7 dominant studies investigating this topic and concluded significant inconsistencies and unable to draw accurate conclusions. He attributes this to the use of different methods, stimuli and sample sizes. Further reinforcing this perspective, Blair et al. (2001) found that psychopathic children are more able to correctly identify emotions when they are more intensely expressed. This was only the case for sad facial expressions. This is peculiar because Blair et al. (2004) failed to find considerable impairments in the recognition of sad expressions even when using further intensified, empirically validated images (Ekman & Friesen, 1976). This also contradicts Hastings et al. (2008) findings as impairments for sad expressions were found at 60% intensity levels. Thus, displaying significant refutation. Further research controlling for limitations such as subject misrecognition between fearful and surprised expressions (Blair et al., 2001; Hastings et al., 2008) and utilising male participants alone will result in greater ecological validity and increased accuracy. Moreover, impairments in the recognition of emotional facial expressions have also been evident in autism, social anxiety disorder and schizophrenia. Thus, only minimal neuropsychological data of specific subgroups can be removed from the general deficits in processing emotional facial expressions, causing implications for future research. 

A second way to identify emotional deficits in psychopathy is to screen FPS experiments. FPS is a physiological reaction to threatening stimuli. Patrick et al. (1993) employed 54 male sex offenders which were formulated into 3 equal groups of non-psychopaths (PCL-R 30) and a mixed group (PCL-R between 20 and 30). PCL-R scores were combined with case histories, psychiatric files and daily description of behaviour to resourcefully ensure psychopathy within participants. This study was deemed the vastest review at the time as this experiment had only been previously conducted on college students. Each participant was shown images either displaying unpleasant, pleasant or neutral stimuli. Continuing consistency, images were previously rated on aspects of arousal by non-psychopaths (Lang & Greenwald, 1988) to ensure that images elicited normative responses as a benchmark to test psychopath’s responses. Physiological measures such as eyeblink response, EMG activity, heart rate (HR) and skin conductance (SC) were recorded. For accurate study comparison, procedures used in studies of college students were replicated. Findings report that mixed and non-psychopath’s showed large FPS responses for unpleasant stimuli, intermediate during neutral and smallest during pleasant. Psychopath’s FPS responses for pleasant and unpleasant stimuli did not differ, and their largest response was displayed for neutral stimuli. An abundance of research demonstrates fear conditioning, specifically a deficit in fear recognition, to be a primary cause of abnormal FPS responses. This is consistent with various studies discussed above that have found deficits specifically in processing fearful expressions. Non-psychopaths and mixed groups displayed accelerated blink reflexes during unpleasant compared to pleasant stimuli. Contrarily, this pattern was not apparent in psychopaths, but, smaller blink reflexes were present during neutral stimuli. Throughout the experiment, subjects displaying either factor 1 and 2 psychopathy traits were separated. Data showed that abnormal blink reflexes to neutral stimuli is associated with characteristics of factor 1 psychopathy and thus demonstrates that emotional deficits appear to be correlated with unusual blink responses. Furthermore, heightened EMG responses were apparent during unpleasant stimuli for mixed and non-psychopathic groups, however, there was no evidence of response in psychopaths. A multi-group comparison shows enhanced deceleration in HR for unpleasant compared to pleasant and neutral stimuli. HR has proven to be dependent on task requirements, thus, depending on the procedure used to elicit emotion (i.e., imaginal stimuli), HR may be accelerated or decelerated (Vrana & Lang, 1990). Additionally, SC responses show increases for pleasant and aversive stimuli compared to neutral stimuli for all groups. This study was later replicated by Patrick (1994) to address potential limitations. Regarding pictures of facial expressions, all images were taken from the International Affective Picture System. Although images are not publicly displayed, it has been inferred that perhaps the aversive images were not distressing enough. Thus, adoption of a larger sample size of 144 male inmates and the use of increased noxious images combined with a noxious loud noise, dysfunctional FPS responses were found. Consistent with Patrick et al. (1993), no SC or HR responses were apparent. 

Although contradictory of Patrick et al. (1993) findings, numerous studies, although dated, have also found this result. While some substantiated evidence for emotional deficits in psychopathy is evident, the focus has solely been placed on males. This may be because males are more likely to be incarcerated than females. Statistics of Federal Bureau of Prisons (2019) shows that 93% of inmates are male, leaving 7% female. Simultaneously, studies have found evidence of emotional deficits in psychopathic females. Sutton, Vitale and Newman (2002) found abnormal FPS responses to unpleasant pictures in 172 psychopathic females. This is consistent with previous research in men (Patrick, 1993, 1994). However, this study tested acoustic startle probes at different durations of picture presentation. It appeared that psychopathic participants demonstrated normal affect modulation responses when probes were presented at the later duration. This pattern has also been found in males. Therefore, this dysfunctional response pattern appears to be a result of a delayed emotional response rather than lack of emotion. Such findings highlight the significance of individual differences in emotional responding and produces ‘food for thought’ for future research. Nevertheless, Melvin (2005) found no difference between 60 psychopathic and non-psychopathic females in an emotional word recognition task. However, self-report measures were used to recruit participants which may be a significant confound as responses can easily be manipulated, especially due to traits of compulsive lying in psychopathy (Hare, 1991). It is important to note that research has found considerable amygdala impairments in psychopaths during affective tasks. Moreover, neuroimaging experiments in psychopaths has highlighted the existence of amygdala impairments. This theory requires additional research, however, as the amygdala has been identified with emotional processing this is a contributing factor to support that psychopath’s have an emotional deficit. 

Although there is evidence suggesting that psychopathic individuals possess a deficit in processing emotional material, inconsistencies in this research are at large (Brook et al., 2013). Notwithstanding, only two measures have been discussed within this essay and a lack of research in female psychopathy make it difficult to generalise these findings. On the other hand, neuropsychological data and plausible theories for inconsistencies may provide the confirmation that psychopaths indeed have an emotional deficit. Overall, taking the above research, it cannot be said for certain that psychopaths have a deficit in processing emotional material.