Biased thinking assessed by external observers in borderline personality disorder.

OBJECTIVES: Biased thinking (to some extent overlapping with the concepts of cognitive distortions and cognitive errors) is a key concept in cognitive therapy of borderline personality disorder (BPD). Specific contents and cognitive processes related to BPD functioning are known. However, most studies are based on self-report measures which present a number of important limitations, in particular the difficulty in assessing non-conscious processes infused by affect. So far, no studies were conducted using valid observer-rated methodology addressing the question of biased thinking in BPD as it unfolds spontaneously in session.

DESIGN: This is a controlled interview study comparing two matched groups, BPD patients and healthy controls.

METHODS: A total of N= 25 clinical dynamic interviews with patients presenting with BPD were transcribed and rated using the Cognitive Errors Rating Scale (Drapeau, Perry, & Dunkley, 2008); their cognitive profiles were compared to those of N= 25 healthy controls who underwent the same procedure.

RESULTS: Overall, results indicated that no between-group difference in the frequency of specific biases was found. However, heightened levels of negative cognitive biases, in particular over-generalizing and fortune-telling, were associated with BPD. Furthermore, negative over-generalizing was associated with the number of BPD symptoms.

CONCLUSIONS: These results have high levels of ecological validity and are promising for the refinement of cognitive theory of BPD. Clinical implications for assessment and intervention are discussed.