Right hemispheric mediation of dream visualization: a case study.

A male patient with extensive damage to the right hemisphere, causing blindness in the left half of his visual field, was studied over two nights in a sleep lab. Dream reports were collected after six awakenings from REM sleep. His dreams were typically sequential and narrative but lacked continuous visual imagery; any visual images were fragmentary and static. He also could not perform waking tasks requiring mental representation of space. These observations suggest that dream narratives may arise from different brain sources than the visual content of dreams, and that visual dream experiences may depend on right-hemisphere processing. Differences from a prior study may be due to different interview techniques.

Study at a glance

Abstract

Our paper addresses, as did a recent study by Greenwood et al. (1977), the question of differential right vs. left hemispheric involvement in REM-sleep dreaming. A male subject with extensive lesioning of the right hemisphere and consequent contralateral homonymous hemianopia was studied for 2 nights in a sleep laboratory where a dream report was collected following each of 6 awakenings from REM sleep. The subject's dream reports were typically sequential and narrative in form, but were lacking specifically in continuous visual imagery. The occasional visual images that appeared in the subject's dreams were described as fragmentary and static in nature. The subject also was unable to perform waking tasks requiring the kinematic representation of extrapersonal space. These observations support the hypotheses that dream narratives may derive from different neurocognitive sources than do the specifically visual realizations of those narratives, and that the visual mediation of dream experience may depend on right-hemispheric processing. Differences between our findings and those of Greenwood et al. may be attributable to differences in dream interview technique.