Summation of semantic priming effects in Parkinson’s Disease and healthy individuals

Abstract

Parkinson’s Disease is characterized by a deficiency in striatal dopamine. Recent research has suggested that dopamine acts as a neuromodulator, which may alter the dynamics of automatic semantic activation. In particular, the research has suggested that Parkinson’s Disease (PD) patients may exhibit a delayed time course of spreading activation during automatic semantic priming tasks (e.g., Arnott, Chenery, Murdoch, & Silburn, 2001). Since delayed semantic processing has the potential to influence performance on various other language processing tasks, it represents an important area of research in PD. The use of multiple primes in a semantic priming task could extend recent findings by allowing the time course of semantic activation to be analysed more specifically.A recent semantic priming experiment by Balota and Paul (1996) investigated the effect of using multiple related prime words. The results revealed a summation of activation, whereby greater magnitudes of priming effects were found when two related primes were used, as opposed to when only the first or second prime word was related to the target.The aim of the present study was to investigate the time course of spreading activation during automatic semantic activation by using the multiple priming paradigm implemented by Balota and Paul (1996). If PD patients do experience a delayed time course of spreading activation, then summation priming would not be expected for the PD group, since sufficient spreading of activation would not have time to occur for both prime words.© 2003 Elsevier Inc.