A randomized trial on differential changes in thought and affect after mindfulness versus dyadic practice indicates phenomenological fingerprints of app-based interventions.

Contemplative practice has demonstrated benefits for mental health and well-being. Most previous studies, however, implemented in-person trainings containing a mix of different, mostly solitary, practices and focused on pre- to post-training outcomes. In this randomized trial, we explore the immediate differential efficacy of two daily app-delivered practices in shifting emotional (valence, arousal) and thinking patterns (thought content on future-past, self-other, positive-negative dimensions). For 10 weeks of daily training, 212 participants (18-65 years) performed either a novel 12-min partner-based socio-emotional practice (Affect Dyad) or a 12-min attention-focused solitary mindfulness-based practice. Using ordinal Bayesian multilevel modeling, we found that both practice types led to more positive affect and higher arousal. However, whereas mindfulness-based practice partly led to a decrease in active thoughts, particularly in future-, other-related and negative thoughts, the Dyad in contrast led to increases in other-related, and positive thoughts. This shift towards more social and positive thoughts may specifically support overcoming ruminative thinking patterns associated with self-related and negative thought content. Overall, these differential findings may help inform the adaptation of scalable app-based mental trainings in different segments of the population with the goal to improve mental health and well-being.