Freud remained rather unimpressed by attempts at experimental testing of psychoanalytic hypotheses because he considered them unnecessary given the wealth of clinical observations available for the purpose (see Freud's letter to Rosenweig). But although many psychoanalytic theories, e.g. infantile sexuality, need no experimental validation, as psychoanalytic knowledge advances there may be hypotheses suggested by observation our confidence in which could be enhanced by experimental testing when it is possible. The Search for Oneness is an attempt by the use of subliminal stimuli to explore the psychic effects of merger fantasies.

The authors take some care to take into account the multi-determined meanings that their subliminal stimulus 'Mommy and I are one' might have. They are careful to consider such