The Nonverbal Behaviour Therapeutic Index (NBTI): Advancing Nonverbal Behaviour Analysis in Mental Health

Abstract

Nonverbal behaviour plays a central role in therapeutic communication, yet existing models prioritise verbal interactions and provide limited guidance on nonverbal behaviour analysis. Current best practices rely heavily on intuitive interpretations of nonverbal cues, which undermines consistency and limits empirical grounding. This paper reviews the ways in which nonverbal behaviour analysis is represented in the literature and synthesises research across psychology, nonverbal communication and credibility analysis to develop the Nonverbal Behaviour Therapeutic Index (NBTI). The NBTI is a novel framework for systematically and explicitly integrating nonverbal behaviour analysis into mental health practice. Its conceptual foundations centre on the observation of indicators of changing arousal, cognition, and emotional processing (Nonverbal ACEs), which inform a psychoeducational feedback loop designed to enhance client self-awareness and self-regulation. Implications for clinical practice, alongside limitations and directions for future research are discussed.