Naming problems in dementia: semantic or lexical?

The naming behaviour was explored of patients moderately deteriorated with probable Alzheimer's disease (pAD) by analysing responses made on a picture naming and two word-picture matching tasks for the same items. Naming responses were classified into target and non-target and the relationship between non-target responses and their targets were explored. It was found that semantic relatedness influenced these non-target responses but frequency and imageability did not. The pAD participants performed significantly better on the two word-picture matching tasks than the naming task, while there was no difference on these within- and between-category tasks. These findings are explored with reference to a two-stage model of lexical access, which has separate storage of semantic, lexical and phonological information. The participants' difficulties appear to lie largely in retrieving the labels for items they comprehend.