Word learning can be achieved without feedback: implications for aphasia therapy.

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.