Hypnosis in many ways represents psychology’s dirty little embarrassment, at the cutting edge of what cannot be explained and has therefore been ridiculed, ignored or relegated to a parlor game. But it is intimately related to, as Posner says, the subjectivity of experience and the active or constructed nature of the perception of ‘objective’ reality. It is also closely related to the clinical phenomenon of dissociation, which is absolutely central to psychopathology but has not been grappled with effectively since psychoanalysis was born with Freud’s deprecation of the central role dissociation had played the theories of predecessors like Janet.

Dissociative responses are a core part of consciousness and range from the everyday to the unbelievably extreme, as in what used to be called multiple personality disorder. When not recognized, patients (usually women with trauma histories) are shoehorned into the Procrustean bed of all sorts of other psychiatric diagnoses. A psychodiagnostician will not see dissociation unless s/he has taken a major leap of faith to be open to it. The flip side of that coin is that it inspires a profound skepticism about the rigidity and self-fulfilling prophecy with which conventional psychiatric diagnosis (read: DSM-IV) is usually done. And such misdiagnosis is not just an academic issue, because the treatment approach to dissociation is very different than, say, bipolar disorder or schizophrenia. Patients whose dissociative symptoms are not recognized are loaded up on all sorts of medications which not only do not help them but have substantial side effects impacting quality of life and, indeed, may worsen their dissociative tendencies.