Tomkins' magnum opus, Affect Imagery Consciousness, was published by Springer Publishing Company in four volumes over 30 years. When Tomkins began writing the book in the 1950's, American psychology was dominated by psychoanalytic and behaviorist theories - neither of which placed much importance on the role of basic emotions in everyday human behavior. Tomkins challenged the status quo by developing - over the span of nearly 2,000 pages -- a theory of consciousness and motivation that placed emotion at the core of the human experience.

Because so few psychologists were studying emotion at that time, Tomkins drew liberally from other academic disciplines to help formulate his ideas and support his arguments: evolutionary biology, ethology, cybernetics, literature, philosophy, psychoanalysis, and neurophysiology, among others. In the process, Tomkins practically invented the field of "nonverbal behavior" through close observation of emotional expressions in people, including his own infant son. His work was a brilliantly eccentric pastiche of ideas that adhered to no strict disciplinary or ideological boundaries. In time, however, AIC came to prominence through the research of his disciples, notably Paul Ekman and Carroll Izzard, who went on to become major researchers in the psychology of emotion. Today, Tomkins's book is influential not just in psychology but in philosophy, sociology, communication studies, even in "affective computing.