This paper suggests that differences in early sensory processing, integration, and differentiation, contribute, in highly specific ways, to characteristics of the ego, deficits in ego functions, and the ego's tendency to employ certain defenses (when certain pathogenic environmental experiences are present). Specifically (1) auditory-verbal-affective vulnerabilities may be associated with disorders of thought and obsessive-compulsive patterns, especially when coupled with environments that tend to confuse affective meanings at behavioral-gestural and symbolic levels; (2) visual-spatial-affective vulnerabilities may be associated with disorders of affect regulation and hysterical patterns, especially when coupled with environments that lack empathy and/or limit setting; (3) spatial, motor movement (vestibular) vulnerabilities may be associated with phobic and/or counterphobic tendencies. The author contends that these hypotheses are sufficiently specific and testable to lead to new research opportunities.