Chatbots are improving at talking like humans, but a new study from USC questions if they can help in therapy. Large language models (LLMs), like ChatGPT, are computer programs that generate human-like text. Researchers suggest these models struggle with the deep connection needed in therapy. Their findings were shared at a 2025 conference on language processing.
Testing Chatbots in Therapy
The study looked at how well LLMs handle linguistic entrainment, which is when two people adjust their speech to match each other, building trust. This is key in therapy to improve outcomes. The researchers used electroencephalography (EEG) to record brain activity from 26 university students. These students used a chat platform with ChatGPT 3.5-turbo for exercises like cognitive restructuring, which helps change negative thoughts, and coping strategies, which manage stress. The platform guided them through prompts to process emotions.
Analyzing the chat records, researchers found that better entrainment led to more sharing and engagement, signs of good therapy. However, compared to human therapists and even online peer supporters, the LLM showed weaker entrainment. This means it didn’t match human conversation skills as well. Some worry LLMs could replace therapists, but the study doesn't support this.
“We’re seeing a concerning narrative that LLMs could replace therapists,” says researcher Mina Kian in an USC press release. “Therapists go through years of schooling and clinical training to prepare for their client-facing role, and I find it highly concerning to suggest that LLM technology could just replace them.”
Instead, LLMs might assist with at-home tasks, not replace clinicians.
The study highlights growing efforts to test LLMs in sensitive areas like mental health care, beyond just mimicking talk. The researchers suggest exploring other therapy types, like motivational interviewing or Dialectical Behavior Therapy (DBT), which helps with emotions. They plan to study socially assistive robots (SARs), devices that support therapy, for anxiety care at home. The goal is to create tools that help therapists reach more people, not take their place.