Computational modeling of reading in semantic dementia: comment on Woollams, Lambon Ralph, Plaut, and Patterson (2007).

Woollams, Lambon Ralph, Plaut, and Patterson reported detailed data on reading in 51 cases of semantic dementia. They simulated some aspects of these data using a connectionist parallel distributed processing (PDP) triangle model of reading. We argue here that a different model of reading, the dual route cascaded (DRC) model of Coltheart, Rastle, Perry, Langdon, and Ziegler (2001), not only provides a more accurate simulation of these aspects of reading in semantic dementia than does the PDP model but also provides highly accurate simulations of other aspects of reading in this disorder that the PDP approach has not simulated. We conclude that our findings add to evidence both from simulations of normal skilled reading and from simulations of other kinds of acquired dyslexia that the nonconnectionist DRC model of reading offers a better account of normal and disordered reading than the connectionist PDP models of reading.