Implicit and Explicit Learning in Aphasia

Introduction Implicit learning is an incidental, inductive learning process that occurs without the use of explicit strategies. To date, few studies have investigated implicit learning subsequent to stroke, and almost all have used visuomotor tasks (e. The present study used a Serial Search Task developed by Goschke and colleagues (2001) to examine implicit and explicit learning of an auditory word sequence in individuals with stroke-induced agrammatic aphasia and healthy age-matched adults. The present study also included a listening sentence span task to evaluate working memory. Research indicates that many aphasic individuals have working memory impairments, which are highly interrelated with language comprehension and overall aphasia severity However, little is known about how working memory deficits relate to learning in aphasia. Methods Participants included 10 individuals with chronic stroke-induced agrammatic aphasia (7 male; age 33-74, M=55) and 18 age-and education-matched healthy controls (9 male; age 46-74, M=61). Aphasic participants exhibited symptoms consistent with agrammatism, as indicated by scores on the and narrative sample analyses (see Tables 1 and 2). Two versions of the Serial Search Task stimuli were developed. Each version consisted of four monosyllabic concrete nouns arranged in an eight-item sequence (e.g., shoe desk cake knife cake desk shoe knife). These words were paired with corresponding black and white line drawings. Stimuli for the listening span task consisted of simple active sentences eight words in length. On each trial of the Serial Search Task (SST), the four pictures were presented horizontally on the computer monitor, with each of the four locations corresponding with a button on a response pad. The pictures were displayed for 500 ms before one of the four words was presented over the speakers. The participant pressed the button corresponding with the location of the word that was spoken, and a blank screen appeared for 500 ms before the beginning of the next trial (see Figure 1). In each trial, the four pictures were randomly assigned to the four locations. In contrast, the auditory stimuli were presented in the order of the 8-item sequence during most of the experiment, with Blocks 1-6 each consisting of ten repetitions of the 8-item sequence of spoken words (i.e., 80 trials per block). Block 7 consisted of 80 trials with the four words occurring in a pseudorandom order. Block 8 returned to sequenced stimuli with ten repetitions of the sequence. In this paradigm, implicit learning of the sequence is indicated by …