Digby Tantam proposes that people are constantly updating and refining their understanding of the social world through the exchange of subtle non-verbal information. This unconscious flow of information between individuals creates a network which he considers to be analogous to the internet, hence his coinage of the term ‘interbrain’. Using this model, he suggests that impairments in non-verbal communication cause individuals with autism-spectrum disorder to have an inefficient connection to the interbrain and this, in turn, is what underlies the social and behavioural difficulties which characterise these conditions.

The book unfolds in a logical and sensible manner, beginning with a thorough introduction to non-verbal communication. In subsequent chapters, Tantam carefully builds his argument by drawing on evidence from research and clinical practice, also discussing the possible biological underpinnings of his ideas. Finally, he covers the extended consequences of non-verbal communication impairment and considers how the interbrain framework can be used to assist in understanding people with autism-spectrum disorder.

The author's influences as a clinical psychotherapist and as a scientist are evident throughout the book and he is particularly impressive at fusing the biological and psychological aspects of autism-spectrum disorder. He makes extensive use of analogy and real-life vignettes to illustrate his ideas, making complex concepts easy to grasp and the book interesting and enjoyable to read. The book's central thesis will strike a chord with anyone who works with people with autism-spectrum disorder, particularly with regard to understanding social impairments, although some will be less convinced that an inefficient interbrain connection is a fundamental cause of the other features of autism-spectrum disorder.