Mental health chatbot does best when acknowledging it's not human

The researchers also noted that Woebot’s bond scores were higher than other internet-based CBT programs.
By Mallory Hackett
11:59 am

Photo: Andrea Piacquadio

The emergence of digital mental health interventions has given traditional modes of treatment the ability to be highly scaled for use whenever and wherever the patient chooses.

These capabilities pose several advantageous characteristics to in-person therapy, but critics of these technology-based platforms continue to raise concerns over something they lack: a human connection between the provider and patient.

A new study examining the effectiveness of one chatbot-based mental health platform, Woebot, suggests that fully automated conversational agents can form similar bonds with users as real-life therapists.


When surveyed using the Working Alliance Inventory-Short Revised (WAI-SR) test to develop a bond score between user and Woebot, the participants’ average scores were consistent to those of traditional modalities for cognitive behavioral therapy delivery.

The average bond subscore for Woebot was 3.84, compared to face-to-face individual CBT and group CBT which were 4.0 and 3.8, respectively.

Among the study participants, women (3.92) and those aged 18-25 (3.96) had the highest reported bond scores.

The researchers also noted that Woebot’s bond scores were higher than other Internet-based CBT programs. They predict that this is because Woebot acknowledges the fact that it’s not a human, while other chatbots attempt to seem like a real person.

“We speculate that transparency and other design elements are key drivers of bond development,” the researchers wrote in the study. “For example, Woebot explicitly references its limitations within conversations and provides positive reinforcement and empathic statements alongside declarations of being an artificial agent.”

The test also scored for goal and task agreement, as well as giving an overall score. The average goal score was 3.25, the average task score was 2.99 and the average total score equaled 3.36.


The study included 36,070 participants over the age of 18 who signed up for Woebot between November 2019 and August 2020. About 57% of the participants identified as female, and the average age range was between 25 and 35.

Within three to five days of their registration, the app prompted users to take the WAI-SR to assess three aspects of the therapeutic alliance: agreement on the tasks of therapy, agreement on the goals of therapy and development of an affective bond.


Woebot debuted in 2017 as an app for Facebook Messenger, where it would engage users in discussions of anxiety or depression. It scored $8 million the following year after launching its standalone app.

More recently, the company released data on a modified version of the Woebot app that treats substance use disorder. The investigation found that 101 participants in the eight-week program reported reduced cravings and increased confidence in their ability to resist urges.

Wysa is another AI-powered chatbot for mental health. Last year, Aetna International inked a deal with Wysa to give its members and their employees free access to the virtual health offering.

Beyond just mental health is virtual care platform Conversa, which operates an Automated Virtual Care and Triage platform. It identifies high-risk patients and then puts them in communication with a healthcare provider via phone calls, telehealth, e-visits or in person.

Babylon Health offers a similar service that allows patients to describe their symptoms to a text-based bot, consult with a provider via video, and store medical information and notes.


“I’ve always believed that technology could be truly helpful at an emotional level, if it’s designed and delivered in a human-centered way,” Alison Darcy, Ph.D., founder and president of Woebot Health, said in a statement.

“The ability to establish a bond, and to do so with millions of people simultaneously, is the secret to unlocking the potential of digital therapeutics like never before. We’re excited to be at the forefront of this line of research.”



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