Murphy discusses the importance of sensory stimulation for ego development. Proper ego development depends in part on sensory 'input'. It is of interest that certain classes of patients 'use' preferential sensory inputs: in hysterical patients vision predominates, in paranoid patients, hearing. The predominant or preferred perceptual channel may determine what childhood situation is traumatic, thus drawing it into conflict. In the analytic situation we may study the increased responses to certain sensory modalities when specific conflicts are mobilized. Both drives and defenses may be expressed through these preferred channels.