A natural language processing approach reveals first-person pronoun usage and non-fluency as markers of therapeutic alliance in psychotherapy

It remains elusive what language markers derived from psychotherapy sessions are indicative of therapeutic alliance, limiting our capacity to assess and provide feedback on the trusting quality of the patient-clinician relationship. To address this critical knowledge gap, we leveraged feature extraction methods from natural language processing (NLP), a subfield of artificial intelligence, to quantify pronoun and non-fluency language markers that are relevant for communicative and emotional aspects of therapeutic relationships.

we identified therapists’ first-person pronoun usage frequency and patients’ speech transition marking relaxed interaction style as potential metrics of alliance. Behavioral data from patients who played an economic game that measures social exchange (i.e. trust game) suggested that therapists’ first-person pronoun usage may influence alliance ratings through their diminished trusting behavior toward therapists. Together, this work supports that communicative language features in patient-therapist dialogues could be markers of alliance.

However, these algorithms are generally trained from the entire set of sentences uttered by a speaker and often provide high dimensional predictive features that are hard to interpret. Indeed, the lack of interpretability of model features in machine learning has been raised as a culprit for clinicians’ reluctance to utilize artificial intelligence in health care.15

The rationale for pre-defining speech features this way is mainly 2-fold. First, the capacity of patients and therapists to communicate each other’s thoughts and emotions adaptively has been identified as a universal factor that impacts alliance and clinical outcomes across heterogeneous psychotherapy practice settings.16 Empirically, increased reference to the self in a dialogue—commonly represented by first-person singular personal pronouns, such as ‘‘I’’ and ‘‘me’’ - has been considered markers of failure to adaptively distance from negative emotional cues17 and internalizing symptoms in the text messages of patients in online therapy.18 The high frequency of self-focus through ‘‘I’’ usage has been generally linked with mental health burden, such as depression,19 post-traumatic stress disorder (PTSD),20 and compulsivity and intrusive thoughts.21 By contrast, the use of ‘‘I’’ as an active voice22 and an interactive agent with a therapist’s discourse23 were associated with positive therapy outcomes, suggesting the importance of engagement in a therapeutic dialogue. Second, relaxed styles during interactions have been observed as markers of highly affiliative relationships.24 For example, the frequency of filler pauses (‘‘um’’), indicating relaxed production of natural speech, was associated with multiple indices of high alliance interactions,25 such as a speaker’s truthfulness,26 emotional suppression,27 and increased attention during a storytelling task in healthy volunteers.28 Linguistic coordination in usage of the similar words and the rates at which they are said between two people have been shown to predict empathy, social support, and positive outcomes in individual therapy29–31 and online mental health support communities.32

DISCUSSION Scalable, yet interpretable markers of patient-therapist alliance in naturalistic psychotherapy sessions can provide timely and clinically actionable feedback in mental health treatment. Here, we analyzed personal pronoun usage and non-fluency markers using feature extraction methods commonly used in NLP, combined with self-reported surveys of alliance and a game theoretic approach toward alliance (i.e. trust game) (Figure 4). Our study provides the first computational evidence that both first-person pronoun and non-fluency are potential language markers that are predictive of therapeutic alliance and interpersonal trust during psychotherapy treatment.

therapists’ expression of ‘‘i,’’ especially with cognitively geared verbs (e.g. ‘‘i do’’, ‘‘i think’’), may have signaled their inadequate responsiveness to patients’ emotional needs, which has been associated with negative treatment outcomes.36 In terms of ‘‘we,’’ one might assume that the usage of such pronoun that signals inclusiveness might correlate with higher, rather than lower alliance. However, when used by therapists, a higher frequency of ‘‘we’’ could have indicated their therapeutic techniques to bring the strained relationships the patients were dealing with into the ‘‘we’’ mode of togetherness.37,38 These speech features not only correlated with patients’ perception of alliance, i.e. self-report, but also with objectively measured behavioral proxies of trust (Figures 3A–3C).

This offers a plausible explanation for our finding that in our sample, patients who reported stronger alliance were more honest and more willing to effectively communicate their emotions to their therapists.