Neighbourhood density, word frequency, and spelling-sound regularity effects in naming: similarities and differences between skilled readers and the Dual Route Cascaded Computational model.

An experiment with skilled readers and a series of simulations with the Dual Route Cascaded model (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001) investigated the joint effects of stimulus quality and Neighbourhood Density (N) in nonword naming. Neighbourhood Density and stimulus quality yielded additive effects on RT for skilled readers whereas the model produced an interaction between these factors. A further set of simulations show that DRC also produces an interaction between stimulus quality and (1) word frequency, (2) spelling-sound regularity, and, (3) nonword letter length. None of these three factors interact with stimulus quality in performance by skilled readers. It is suggested that DRC's assumption of cascaded processing throughout represents a central problem. A proposal as to how the model can be modified to accommodate these and other problematic data is discussed.