Some Incidental Observations on Modal Specificity
Mark Solms · Psychology Press eBooks · 2014
As we saw in chapter 3, Charcot’s explanation of nonvisual dreaming as a loss of stored modality-specific representations was elaborated by Griinstein (1924). Griinstein observed that whereas visual dream-imagery is lost in cases of visual agnosia and irreminiscence (i.e., in cases with damage to secondary visual cortex), it is not affected in cases of cortical blindness (i.e., in cases with damage to primary visual cortex). This confirmed Charcot’s interpretation of nonvisual dreaming as a disorder of visual memory. Griinstein concluded on this basis that the syndrome of nonvisual dreaming is specifically associated with damage to visual association cortex. He then predicted that analogous modality-specific dream disorders should arise from damage to secondary cortex outside of the visual sphere. For example, patients with lesions in sec ondary auditory cortex should experience nonauditory (or nonverbal) dreams. Griinstein himself was unable to confirm this prediction in two cases of pure word-deafness, because both of them reported global cessation of dreaming (see Table 2.2). His hypothesis therefore remains of theoretical interest today, as it has still not been systematically investigated. It was not included in the 18 hypotheses formally investigated in the present study. However, the following incidental observations are of interest in this regard.