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Kihlstrom claims that “[c]ontemporary cognitive science has no problem with the idea of … hierarchies of modules, or with constraints on communications among them.” Hilgard's neodissociation theory has these features. Kihlstrom uses Hilgard's model to provide a framework for conceptualizing four types of relations between conscious and nonconscious mental processing:
1A selective impairment in one cognitive subsystem, leaving another intact: blindsight studies “suggest that there are two visual systems, one projecting to the occipital cortex and another projecting to the superior colliculus.” An intact collicular system allows responses to visual stimulation even when striate damage prevents awareness of such visual stimulation.
2A disruption of communication between two intact subsystems: certain types of aphasia, for example, may be caused by damage to nerve fibers connecting Wernicke's area with Broca's area.
3A disruption of communication between an intact subsystem and an executive ego: hypnosis, negative hallucinations, certain forms of amnesia, positive hallucinations, involuntary motor actions, all fit here. Also fitting this model, Kihlstrom claims, are the acquisition and use of language, as well as the operation of some detectors of visual features.
4A selective impairment in the functioning of the executive ego itself, leaving the subsystems intact: surgical patients under general anesthesia with some implicit memory spared, and patients with multiple personalities or psychogenic fugue suggest intact subsystems but executive ego malfunction.