Visuoperceptual performance was examined in 146 9- to 12-year old children for whom prenatal exposure to marihuana and cigarettes had been ascertained. The subjects, participants in an ongoing longitudinal study, were from a low-risk, predominantly middle class sample. The tasks ranged in complexity from those that required basic visuoperceptual skills to those that required considerable integration and cognitive manipulation of such skills. Trend analysis revealed a dose dependent negative association between prenatal cigarette exposure and an overall score reflecting basic visuoperceptual functioning. This association remained after consideration of potential prenatal confounds, pre- and postnatal secondhand smoke exposure, and the nonperceptual demands of the tasks. This poorer performance in the basic visuoperceptual domain underlay a poorer performance in more complex visuoperceptual tasks among the offspring of cigarette smokers. In contrast, prenatal marihuana exposure was not associated with basic visuoperceptual functioning but was negatively associated with performance in visual problem solving situations. The interpretation of the marihuana findings is discussed in relation to a "top-down" integrative ability associated with executive function, the extant prefrontal literature, and earlier observations of this sample. (C) 1999 Elsevier Science Inc. All rights reserved.
