JMIR Publications

ABSTRACT

Background:

Mental health chatbots are increasingly used to address the global mental health treatment gap by offering scalable, accessible, and anonymous support. While prior research suggests that users may develop relationships with these chatbots, the mechanisms and individual differences underlying such relational experiences remain underexplored. As the concept of the Digital Therapeutic Alliance (DTA) gains traction, a deeper understanding of subjective relationship-building processes is essential to inform the design of more effective digital mental health interventions.

Objective:

This study aimed to investigate how users subjectively perceive and develop relationships with mental health chatbots over time. We sought to identify key experiential dimensions and interactional dynamics that facilitate or hinder the formation of such bonds, contributing to the evolving conceptualization of the DTA.

Methods:

We conducted a four-week longitudinal diary study with 26 adult participants who interacted with two widely available mental health chatbots (Woebot and Wysa). Data were collected through weekly surveys, conversation screenshots, and semi-structured interviews. A reflexive thematic analysis was used to identify recurring themes and interpret the emotional, communicative, and contextual factors shaping participants’ relational experiences with the chatbots.

Results:

Eighteen participants reported forming a bond or light bond with at least one chatbot. Interview narratives revealed three relational categories: Bond (clear emotional connection), Light Bond (tentative or partial connection), and No Bond (absence of connection). Both participants with lower and higher psychological well-being (based on WHO-5 scores) reported forming such relationships, suggesting that bonding capacity is not strictly dependent on mental health status. Thematic analysis identified six key themes influencing relationship formation: (1) preferences for leading or being guided in conversation; (2) alignment between users’ expressive styles and chatbot input constraints; (3) expectations for emotional care and warmth; (4) perceived relevance and effectiveness of chatbot guidance; (5) appreciation for a human-like, conversational tone; and (6) valuing a private, non-judgmental space.

Conclusions:

Our findings contribute empirical insight into how users interpret and engage in relational processes with mental health chatbots, thereby advancing the theoretical foundation of the DTA. The study highlights the role of emotional credibility, communicative nuance, and user agency in shaping therapeutic connection. Design features such as affective tone, personalization, and expressive flexibility may foster an emotional bond, improve user retention, and enhance the therapeutic value of digital mental health tools.