M. Sitton et al., Superadditive effects of multiple lesions in a connectionist architecture:Implications for the neuropsychology of optic aphasia, PSYCHOL REV, 107(4), 2000, pp. 709-734
Neuropsychological disorders have traditionally been understood in terms of
a focal lesion to a single component of a cognitive architecture. Optic ap
hasia (OA) defies explanation in this way. In OA, naming of visual stimuli
is impaired in the absence of general Visual agnosia or anemia. OA has been
explained by positing multiple semantic systems or multiple functional pat
hways to visual naming. M. J. Farah (1990) instead sketched a parsimonious
account based on multiple lesions-to pathways mapping visual input to seman
tics and semantics to naming responses-and the assumption that the effects
of the lesions are superadditive. The authors demonstrate superadditive eff
ects of damage in a connectionist architecture and model other phenomena as
sociated with OA. Multiple lesions with superadditivity provide a novel cla
ss of explanations for neuropsychological deficits that previously seemed t
o imply the existence of highly specialized processing components.