For at least half of the twentieth century, psychology and the other mental health professions all but ignored the significant adaptive pos- sibilities of the human gift of imagery. Our capacity seemingly to duplicate sights, sounds, and other sensory experiences through some form of central brain process continues to remain a mysterious, alma st miraculous skill. Because imagery is so much a private experience, experimental psychologists found it hard to measure and turned their attentian to observable behaviors that could easily be studied in ani- maIs as well as in humans. Psychoanalysts and others working with the emotionally disturbed continued to take imagery informatian se- riously in the form of dream reports, transferenee fantasies, and as indications of hallucinations or delusions. On the whole, however, they emphasized the maladaptive aspects of the phenomena, the dis- tortions and defensiveness or the "regressive" qualities of daydreams and sequences of images. The present volume grows out of a long series of investigations by the senior author that have suggested that daydreaming and the stream of consciousness are not simply manifestations in adult life of persist- ing phenomena of childhood. Rather, the data suggest that imagery sequences represent a major system of encoding and transforming information, a basic human capacity that is inevitably part of the brain's storage process and one that has enormous potential for adap- tive utility. A companian volume, The Stream of Consciousness, edited by Kenneth S. Pope and Jerome L.