THE EFFECT OF RATE OF PRESENTATION AND REPETITION ON VERBAL PERSEVERATIONS IN APHASIA: IMPLICATIONS FOR PRIMING ACCOUNTS

Stephen J. Gotts (1), Antonio Incisa della Rocchetta (2) & Lisa Cipolotti (2)
(1) Dept. of Psychology, Carnegie Mellon University, Pittsburgh, PA.
(2) National Hospital for Neurology and Neurosurgery, London, England.

A verbal recurrent perseveration is the inappropriate repetition of a recent utterance when a different response is expected (Sandson & Albert, 1984). Several accounts have suggested that such perseverations result when processing of the current stimulus is too weak or slow to dominate a recently primed response (e.g. Cohen & Dehaene, 1998; Martin, et al, 1998; Plaut & Shallice, 1993). We present data from several picture-naming experiments conducted with an anomic patient (E.B.) which require further specification of current proposals. Small sets of pictures were repeatedly presented for naming at a fixed response-stimulus interval (RSI), either fast (1 sec) or slow (10-15 sec). Consistent with existing priming accounts, perseverations were more likely after one within-block repetition and when the current target name was of low frequency. However, there was no difference in the number of perseverations produced under a fast vs. slow RSI, and the rate of decay was far slower with a slow RSI. We present a simple computational model of these results which appeals to recent theories of the neural basis of priming (Desimone, 1996; Wiggs & Martin, 1998) and a similar spacing effect observed in the presynaptic depression of neurons (Byrne, 1982).


Back to Steve's Home Page

This page last updated 13 January 1999.