Normal mind-reading capacity but higher response confidence in borderline personality disorder patients

Authors


Lisa Schilling, MS, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany. Email: l.schilling@uke.uni-hamburg.de

Abstract

Aim:  Borderline personality disorder (BPD) is characterized by a pattern of instability in interpersonal relationships. Therefore, the investigation of social cognition is of compelling interest for the understanding of BPD. One important aspect of social cognition is theory of mind (ToM), which describes the ability to understand others' mental states, such as beliefs, desires and intentions. The aim of the present study was to further investigate ToM in BPD patients.

Methods:  The Reading the Mind in the Eyes Test was assessed in 31 BPD patients and 27 healthy controls. In addition, the test was complemented by a response confidence rating.

Results:  BPD patients and healthy controls did not differ in their mind-reading ability with respect to accuracy, but patients were significantly more often highly confident in their decisions than controls.

Conclusions:  Overconfidence might contribute to the severe difficulties in interpersonal relationships often observed in BPD patients.

BORDERLINE PERSONALITY DISORDER (BPD) is characterized by a pervasive pattern of instability in interpersonal relationships, self-image and affect as well as fear of abandonment and marked impulsivity. Emotional dysregulation, consisting of enhanced emotional sensitivity, represents a core feature of BPD1–3 and contributes to interpersonal difficulties. More generally, dysfunctional self-regulation seems to be particularly severe in the context of social relationships.4 Therefore, social cognition is of compelling interest in BPD and, thus, increasingly targeted for therapeutic strategies.5,6 For example, mentalization-based treatment (MBT) has been shown to be effective in the treatment of BPD.7–9 The authors of MBT conceptualize that a fragile mentalizing capacity, defined as ‘the process by which we make sense of each other and ourselves, implicitly and explicitly, in terms of subjective states and mental processes’,9 results from early trauma and non-validating familiar relationships.

Following the hypothesis of enhanced emotional sensitivity and reduced mentalizing capacities in BPD, several studies investigated facial emotion recognition as one important aspect of social cognition or rather theory of mind (ToM), that is, the ability to understand others' mental states, including beliefs, desires and intentions. Levine et al. reported that BPD patients had a lower accuracy of recognizing emotional facial expressions than non-BPD controls.10 This finding was replicated by Bland et al.11 In contrast, others found an enhanced facial emotion recognition in BPD, especially for fearful faces.12 Correspondingly, two studies using morphed pictures of facial affect arrived at inconsistent results3,13 but, as shown in a very well conducted study by Minzenberg et al., the respective paradigm seems to play an important role.14 They found that BPD patients showed a poorer recognition of facial and vocal emotion only when these were displayed together, but not when expressions were presented separately. Hence, the authors suggested that BPD patients may suffer from subtle deficits, which are seen only in more complex tasks involving a higher order heteromodal integration of emotion expression. In a recent review, Domes et al. concluded that there are only subtle impairments in the patients' accuracy to label emotions,15 but they emphasized that BPD patients show a bias towards negative emotions, that is, they tend to project more negative, aggressive or malevolent motives in others,6,16 especially when processing time is limited.17 Most recently, Unoka et al. reported that BPD patients were less accurate than healthy controls in the discrimination of negative but not in the recognition of happy facial expressions.18

Regarding ToM, prior research in BPD using for example the Advanced Theory of Mind Test,19,20 a cartoon task,21 the Understanding ‘Faux pas’ task,22,23 or a trust game with emotional facial cues24 has indicated a trend towards an equal or even superior ToM performance in BPD patients relative to controls.

For the present study, we investigated ToM using the Reading the Mind in the Eyes Test (RMET). To the best of our knowledge, only one prior study used the RMET in patients with BPD, who achieved a better performance compared to healthy controls.5 A normal or even better-than-normal mind-reading capacity in BPD patients, however, is in contrast to their severe interpersonal conflicts and difficult relationships. This may be explained by the degree of confidence that individuals have in their mind-reading abilities, because the behavioral impact of high-confidence errors is more momentous compared to errors for which some degree of doubt has been expressed.25

METHODS

Participants

The study included 31 patients with BPD and 27 healthy controls. Patients were recruited at the Department of Psychosomatic Medicine and Psychotherapy, University Medical Center Hamburg-Eppendorf and Schön Klinik Hamburg-Eilbek, and the Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Germany. Healthy subjects were drawn from an existing subject pool or via word of mouth. Written informed consent was obtained from all subjects. The study was approved by the Ethics Committee Hamburg. BPD diagnoses were verified using the Structured Clinical Interview for DSM-IV Axis II personality disorders (SCID-II).26 Exclusion criteria in the BPD group consisted of: current or lifetime schizophrenia, alcohol or drug dependence (last 6 months), bipolar disorder, schizoaffective disorder, major depression with psychotic symptoms, anorexia or cognitive impairment as assessed on the Structured Clinical Interview for DSM-IV Axis I disorders (SCID-I).27 Twenty-one patients were diagnosed as having current depression, 15 had at least one anxiety disorder, seven suffered from bulimic or binge eating symptoms, four suffered from substance abuse and one had a somatoform disorder. Twenty-five of the 31 patients were treated with psychotropic medication. The absence of mental disorders in healthy participants was verified using the Mini International Neuropsychiatric Interview (MINI).28 Intelligence was measured with the Multiple Choice Vocabulary Test.29 Groups did not differ significantly with regard to age (t(56) = 1.69, P = 0.095) or educational level (t(56) = 1.18, P = 0.241). The BPD group included more women than men compared to the control group (χ2(56) = 19.78, P < 0.001), and the control group scored higher than the BPD patients on the intelligence measure (t(56) = 4.06, P < 0.001).

Reading the Mind in the Eyes Test

For the present study the revised version of the RMET was used.30 In total, 36 black-and-white photographs of the eyes region of different human faces were presented. Participants were asked to identify the emotion that the depicted person was feeling using a forced-choice paradigm: For each photo four possible adjectives were offered and the subject had to decide which one best described the emotion of the person in the photo. Additionally, we complemented the task by a confidence rating: subjects had to specify how confident they were with their decision (‘100% sure’, ‘rather sure’, ‘rather unsure’ or ‘guessed’). An answer was assumed to be highly confident if rated as 100% sure. Moreover, we assessed mental state valence subscores (eight positive, 12 negative and 16 neutral items) using the classification by Harkness et al.31

Statistical analysis

Statistical analysis was conducted using spss version 15.0. An alpha level of 0.05 (two-tailed) was used for all statistical tests. Between-group comparisons were performed using t-test and χ2-test. Analysis of covariance was performed to control for possible confounding variables.

RESULTS

There were no significant group differences concerning the number of correct and incorrect items (Table 1). Moreover, BPD patients showed no specific difficulties in identifying negative, neutral or positive emotions but performed similarly to controls (Table 2). Regarding confidence in decisions made, we found that BPD patients rated significantly more decisions with high-confidence (‘100% sure’) than the controls. This was found for both correctly and incorrectly answered items. In addition, BPD patients made more highly confident answers for neutral and positive but not for negative items (trend level). Overall, we found that BPD patients and controls did not differ significantly in the number of ‘guessed’ or ‘rather unsure’ decisions, but controls evaluated significantly more correct decisions as ‘rather sure’. There were no differences between patients with or without major depression or with or without anxiety disorder, respectively, concerning the RMET results.

Table 1.  RMET performance and answer confidence (mean ± SD)
 BPDControlsStatistics
  1. BPD, borderline personality disorder; RMET, Reading the Mind in the Eyes Test.

Correct items (total)25.1 ± 3.625.7 ± 3.9t(56) = 0.57, P > 0.5
 Negative items8.5 ± 1.98.9 ± 1.9t(56) = 0.615, P > 0.5
 Positive items5.7 ± 1.25.4 ± 1.8t(56) = −0.654, P > 0.5
 Neutral items10.9 ± 2.011.4 ± 1.8t(56) = 1.058, P > 0.2
Incorrect items (total)10.9 ± 4.010.3 ± 3.7t(56) = −0.57, P > 0.5
Guessed   
 Correct items1.2 ± 1.70.8 ± 1.3t(56) = −1.06, P > 0.2
 Incorrect items1.3 ± 1.80.9 ± 1.0t(56) = −0.87, P > 0.3
Rather unsure   
 Correct items4.5 ± 3.75.6 ± 2.8t(56) = 1.30, P > 0.2
 Incorrect items3.5 ± 2.64.0 ± 2.6t(56) = 0.70, P > 0.4
Rather sure   
 Correct items11.0 ± 5.715.2 ± 4.2t(56) = 3.16, P = 0.003
 Incorrect items3.9 ± 2.75.0 ± 3.6t(56) = 1.24, P > 0.3
Highly confident   
 Correct items8.5 ± 7.44.1 ± 4.2t(56) = −2.71, P = 0.009
 Incorrect items2.2 ± 3.20.4 ± 0.7t(56) = −2.75, P = 0.008
Table 2.  RMET performance for high-confidence answers (mean ± SD)
 BPDControlsStatistics
  1. BPD, borderline personality disorder; RMET, Reading the Mind in the Eyes Test.

Negative items   
 Highly confident correct2.7 ± 3.01.6 ± 1.6t(56) = −1.880, P = 0.066
 Highly confident incorrect0.5 ± 1.00.2 ± 0.4t(56) = −1.870, P = 0.069
Positive items   
 Highly confident correct2.1 ± 1.91.0 ± 1.2t(56) = −2.719, P = 0.009
 Highly confident incorrect0.7 ± 1.10.2 ± 0.5t(56) = −2.332, P = 0.025
Neutral items   
 Highly confident correct3.6 ± 3.21.6 ± 1.9t(56) = −2.910, P = 0.005
 Highly confident incorrect1.0 ± 1.70.1 ± 0.3t(56) = −3.020, P = 0.005

Re-analysis of the data controlling for possible confounders (such as gender, intelligence and age) did not yield different findings (all significant: F > 3.7, P < 0.05; all not significant: F < 1.4, P > 0.2).

DISCUSSION

In the present study, BPD patients and healthy controls did not differ with regard to mind-reading accuracy. This result is in line with those of other recent studies reporting normal or even enhanced ToM performance in BPD patients,5,20,24 suggesting a heightened sensitivity to facial emotions3,12,13 or even a kind of ‘hypermentalization’ ability.24 Findings concerning sensitivity to facial emotions, however, have remained inconsistent,15 with some studies reporting a lower accuracy of expression recognition.10,11

The aim of the present study was to explore for the first time how confident BPD patients are about their decisions in the RMET. Interestingly, they were more often highly confident about their rating than controls. Thus, further studies should investigate whether the present observation might be interpreted as an overconfidence bias, indicating a metacognition distortion,32 or whether results reflect a generally extreme evaluation or response style of BPD patients.33 Given that social interactions are often ambiguous and open to different interpretations, high-confidence responses and judgments of interpersonal situations may be hazardous because they are usually rigid and hard to revise. This consideration may explain why BPD patients, despite their overall normal social cognition, are prone to interpersonal conflicts: incorrect social inferences expressed with high confidence (e.g. misinterpretation of a neutral face as hostile with high confidence) have far more severe consequences and higher behavioral impact than incorrect judgments that are associated with some doubt. The latter but not the former will likely prompt further reasoning processes that may help to correct the false judgment, thus attenuating or even preventing social conflicts. Whether deficits in decision making that have also been reported in BPD34 are associated with overconfidence bias deserves further investigation. Furthermore, impulsivity in BPD might contribute to incautious decisions that are committed spontaneously. In further experiments it should be tested as to whether these decision are stable over time or whether BPD patients change their decision or feel less confident. There is need for a replication of these findings, including measurements investigating the potentially underlying mechanisms.

There are some limitations to the study that should be acknowledged. First, most patients suffered from comorbid mental disorders, which is typical for BPD.35 Thus, exclusion would have led to the sampling of a non-representative patients group. Despite the fact that we could not find differences between BPD patients with and without depression or anxiety disorder, further studies should investigate more precisely defined subgroups of BPD. Moreover, we did not include a patient control group, for example, patients with personality disorders other than BPD. Although it remains unclear whether the present findings are specific to BPD, several lines of evidence suggest that patients with depression are underconfident in their judgments.36 Patients with schizophrenia in turn show a pattern of overconfidence in errors along with decreased accuracy in cognitive tasks.37,38 Third, although the present samples were matched with respect to age and educational level, it would have been helpful to have measures of potential confounders, for example, emotion regulation, impulsivity, and psychopathology. Future studies should include such relevant questionnaires and also add assessment of emotion regulation (e.g. psychophysiological paradigms). In addition, effects of psychotropic medication (e.g. antidepressants) should be controlled in future studies. Furthermore, emotion recognition ability as well as answer confidence should be investigated with regard to different emotion types (positive vs negative). Finally, the effect of time limitation on the accuracy of emotion recognition and decision confidence should be examined.

In summary, the main result of the present study was that BPD patients were found to have uncompromised mind-reading capacities but a higher response confidence compared to controls.

ACKNOWLEDGMENTS

This study was not funded by any industry source. There is no conflict of interest for any of the authors.

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