Sequential learning in individuals with agrammatic aphasia: evidence from artificial grammar learning

Abstract

We examined sequential learning in individuals with agrammatic aphasia (n = 12) and healthy age-matched participants (n = 12) using an artificial grammar. Artificial grammar acquisition, 24-hour retention, and the potential benefits of additional training were examined by administering an artificial grammar judgment test (1) immediately following auditory exposure-based training, (2) one day after training, and (3) after a second training session on the second day. An untrained control group (n = 12 healthy age-matched participants) completed the tests on the same time schedule. The trained healthy and aphasic groups showed greater sensitivity to the detection of grammatical items than the control group. No significant correlations between sequential learning and language abilities were observed among the aphasic participants. The results suggest that individuals with agrammatic aphasia show sequential learning, but the underlying processes involved in this learning may be different than for healthy adults.

Keywords: Agrammatic aphasia; artificial grammar; retention; sequential learning.

Conflict of interest statement

Disclosure statement: No potential conflict of interest was reported by the authors.

Figures

Figure 1

Artificial grammar. The rules of the artificial grammar (1a) and the pseudowords assigned to the five lexical categories (1b) were adapted from Saffran (2002). S = Sentence; AP, BP, CP = Phrases; A, C, D, F, G = Lexical categories.

Figure 2

Study design. Training consisted of exposure to auditory grammatical sentences in the artificial grammar. The test that was administered three times required judgments for grammatical and ungrammatical sentences.

Figure 3

Artificial grammar judgment sensitivity. Individual d′ scores are shown overlaid on bars representing the average d′ scores for each participant group at Test 1 (day 1 after training), Test 2 (day 2 before training), and Test 3 (day 2 after second training). Higher d′ scores indicate greater sensitivity to the detection of grammatical items.

Figure 4

Associations between linguistic and sequential learning abilities. Graphs display the associations between aphasic participants'd′ scores across the three artificial grammar judgment tests and their scores on tests of syntactic abilities in comprehension (4a), syntactic abilities in production (4b), and severity of aphasia (4c). No significant correlations between linguistic and sequential learning abilities were observed.