Cross-modal semantic and homograph priming in healthy young, healthy old, and in Alzheimer's disease individuals

Two experiments are reported that explore the influence of strength of the prime-target relationship on the observed priming effects in young, healthy old, and individuals diagnosed with dementia of the Alzheimer type (DAT). In Experiment 1, participants were auditorily presented primes (FURNITURE) and after varying delays presented visual targets that were (1) high-streng th related (e.g., SOFA), (2) low-strength related (e.g., RUG), or (3) unrel ated control words (e.g., COW or DEER). The results indicated that the DAT individuals produced relatively larger priming effects than both the young and the healthy old, but these data could be accommodated by increases in e ffect size due to general slowing of response latencies. In Experiment 2, t he same cross-modal priming paradigm was used with ambiguous words presente d as primes (e.g., BANK) and either high-dominant (e.g., MONEY) or low-domi nant (e.g., RIVER) words as targets. The results of Experiment 2 produced a qualitatively distinct pattern of priming that indicated DAT individuals o nly produced priming for high-dominant targets and not for low-dominant tar gets, whereas, the healthy control groups produced equivalent priming for b oth high- and low-dominant targets. The discussion focuses on the implicati on that these results have for the interpretation of semantic priming effec ts, in general, along with implications for the apparent semantic memory lo ss in DAT individuals.