ABSTRACT
OBJECTIVE: Increased attention has recently been paid to the well-being and flourishing of patients in psychotherapy. This study investigated the occurrence of positive affect (PA) and strength-based behaviours within psychotherapy sessions contrasting positive versus neutral imagery instructions. METHODS: This is a secondary analysis of a randomized controlled trial. Seventy-eight sessions of cognitive behavioural therapy involving 26 patients (69.23% female; Mage = 40.31) treated by 13 therapists were selected. PA and strength-based behaviours of patients and therapists were coded on a minute-by-minute basis with the Resource-Oriented Microprocess Analysis. Each session started with a brief mental imagery instruction. Data were analysed using multilevel modelling. RESULTS: Mild levels of PA were very common, whereas stronger expressions were occasional, especially at the beginning and end of sessions. Strength-based behaviours were employed in one-fifth of the videos analysed. Therapists in the positive imagery instruction showed more strength-based behaviours in the beginning phase of sessions, p < 0.05. The two imagery instructions significantly differed in the session trajectories of PA, p < 0.05. A quadratic trend with higher initial values and a sharper decline in PA were found in the positive instruction, whereas the neutral instruction showed a flatter trend. CONCLUSION: Patients and therapists experience PA and discuss strengths in psychotherapy sessions despite patients' distress. The positive imagery instructions potentially induced a positive focus at baseline for therapists but had a negligible effect on the subsequent session progression. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03767101 (registered December 6, 2018).