DIFFERENTIAL-EFFECTS OF EARLY HEMISPHERE DAMAGE ON LEXICAL COMPREHENSION AND PRODUCTION

The effects of early hemisphere damage on lexical development were inv estigated in 33 children with unilateral left (n = 21) or right (n = 1 2) hemisphere damage and 16 normal healthy controls. Single-word namin g was assessed using the Expressive One-Word Picture Vocabulary Test ( EOW) and lexical comprehension was assessed using the Peabody Picture Vocabulary Test-Revised (PPVT-R). Left lesion subjects (LL) performed comparable to controls in naming, but scored lower than controls on th e PPVT-R. Right lesion subjects (RL) scored lower than controls and LL subjects on both the EOW and the PPVT-R. The unexpected superiority o f LL in comparison to RL children on the EOW and the PPVT-R argues aga inst a simple left hemisphere dominance for early lexical development. RL subjects' significant comprehension deficits failed to correlate w ith more general measures of verbal intelligence supporting a speciali zed role of the right hemisphere in mediating the acquisition of word meaning.