Affiliations: Department of Neurology, University of Münster,
Münster, Germany
Note: [] Corresponding author: Dr. Caterina Breitenstein, Dept. of
Neurology, University of Münster, Albert-Schweitzer-Strasse 33, 48129
Münster, Germany. Tel.: +49 251 8349969; Fax: +49 251 8348181; E-mail:
caterina.breitenstein@uni-muenster.de
Abstract: Purpose. Children acquire new words through exposure, without the
necessity for explicit feedback by caregivers. In aphasia therapy, feedback to
the patient is considered an important asset even though the empirical base
demonstrating superior learning with online feedback is lacking. The present
study examined if healthy adults and patients with chronic aphasia can acquire
a new lexicon by intense frequency of exposure alone. Methods. We compared learning rates with "frequency of exposure
alone" (no-feedback condition: n = 19 healthy adults; two patients with
chronic Broca's and Wernicke's aphasia, respectively) with a condition where
subjects additionally received online feedback (feedback condition; n = 19).
The learning principle was higher statistical co-occurrences of "correct"
picture-pseudoword pairings as compared to "incorrect" pairings. In the
feedback condition, immediate online feedback on the correctness of respective
choices was additionally provided. Results. Both healthy groups successfully acquired the vocabulary.
Feedback led to a slight initial acceleration of learning but did not improve
latency to peak performance or long-term retention of lexical knowledge. These
findings show that high frequency interactive exposure is a potent word
learning mechanism in adults and that feedback is not crucial. This is further
corroborated by our successful training of two patients with chronic aphasia
without online feedback. Conclusions. Our findings demonstrate that word re-learning in
aphasia could benefit from maximizing on the frequency of exposure and
exploiting the therapeutic principle of "massed practice", which has been
successful in physical rehabilitation after stroke. Additionally, economizing
on feedback may prevent patients becoming discouraged by continuous
confrontation with their deficits.
Keywords: language acquisition, associative learning, aphasia, aphasia therapy, feedback
