Pesky gNats

Pesky Logo Pesky gNats is a computer game that implements core elements of Cognitive Behavioural Therapy (CBT). It is designed to support face-to-face clinical interventions with adolescents aged 9-15.
Pesky gNats is available to mental health professionals who work with young adolescents. Full details of how to access the Pesky gNats software and training is available at


Cognitive Behavioural Therapy (CBT) is the recommended treatment for the range of common mental health difficulties in adults. This success has prompted a lot of effort to develop similar CBT interventions for children and teenagers. However, as originally developed, CBT is not very child friendly.

The Pesky gNats intervention helps to address this challenge. It is a computer game designed for used with young people aged 9-15. It builds on research in developmental and clinical psychology and in computer science to help translate an abstract adult therapy into something that is accessible to younger children. Adolescents will play the game over the course of 6 to 8 sessions, together with a suitably qualified adult therapist who understands CBT. The therapist and adolescent sit together at a computer. Rather than talking face-to-face with the adolescent, the therapist acts as a partner in their exploration of the game world. This approach can help to reduce the difficulties many young people experience with face-to-face interventions and assist in creating a fun and experiential process. It provides adolescents with an active process and supportive scaffolding in which to develop and apply CBT ideas, and a de-stigmatising way to engage children in mental health treatments.

In Pesky gNats players visit a tropical island and meet a team of wild life explorers. This team introduces mental health concepts using spoken conversation, embedded animations, videos and questions regarding the player’s own situation. CBT concepts are introduced using concrete metaphors. Negative automatic thoughts are presented as little creatures called gNats that can sting people, causing negative thinking. Each type of gNat is introduced with a cartoon, voiceover and story describing its effects. For example being stung by a Black and White gNat can cause people to think in extremes. Through conversations with game characters players are introduced to strategies for identifying and challenging negative thoughts. Metaphors such as catching, trapping and swatting gNats are used to describe this process. Similar approaches are used with other important CBT concepts, such as Core Beliefs.

The materials in the Pesky gNats game are adapted from the CBT Workbook for Young People by Gary O’Reilly.

The development of Pesky gNats was supported by SBRI Healthcare through a research project at the University of Bristol. Upon completion of the project the university kindly granted Handaxe Limited a cost-free licence for the Pesky gNats software, enabling us to continue developing the game and make it widely available.

The game was developed in collaboration with Opposable Games, a Bristol based games development company. Development was also supported by the Department of Computer Science at the University of Bristol and the Department of Psychology at University College Dublin.

Pesky gNats builds on several years of research by David Coyle and Gary O’Reilly. This research was supported by many people, including Gavin Doherty at Trinity College Dublin and Nicola McGlade at University College Dublin.

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