Muriel Vandenberghe

Can amnesic patients learn without awareness? New evidence comparing deterministic and probabilistic sequence learning.

Can associative learning take place without awareness? We explore this issue in a sequence learning paradigm with amnesic and control participants, who were simply asked to react to one of four possible stimuli on each trial. Unknown to them, successive stimuli occurred in a sequence. We manipulated the extent to which stimuli followed the sequence in a deterministic manner (noiseless condition) or only probabilistically so (noisy condition). Through this paradigm, we aimed at addressing two central issues: first, we asked whether sequence learning takes place in either condition with amnesic patients. Second, we asked whether this learning takes place without awareness. To answer this second question, participants were asked to perform a subsequent sequence generation task under inclusion and exclusion conditions, as well as a recognition task. Reaction times results show that amnesic patients learned the sequence only in the deterministic condition. However, they failed to be able to reproduce the sequence in the generation task. In contrast, we found learning for both sequence structures in control participants, but only control participants exposed to a deterministic sequence were successful in performing the generation task, thus suggesting that the acquired knowledge can be used consciously in this condition. Neither amnesic nor control participants showed correct old/new judgments in the recognition task. The results strengthen the claim that implicit learning is at least partly spared in amnesia, and the role of contextual information available for learning is discussed.

Taux élevé d’erreurs de remplissage du pilulier chez des personnes âgées cognitivement saines

An appropriate medication management depends on executive system integrity, which can be affected by aging. Previous studies showed that seniors commit frequent errors when having to fill in a pillbox. Nevertheless, to the best of our knowledge, no study has really considered the absence of cognitive disorders in the studied sample. The present study aimed to investigate pillbox filling in cognitively healthy elderly (specially focusing on executive system preservation) for whom no cognitive deterioration neither any depressive episode had occurred during a one year period. The filling task has been completed using a weekly pillbox and eight fictitious drugs. The selection of the 27 seniors aged from 71 to 90 years has been based on their results to neuropsychological tests (Trail making test, Stroop Victoria, Tower of London, Montreal cognitive assessment) and a depression assessment scale (Short geriatric depression scale). Results showed that 67% of the participants committed at least one error when filling the pillbox and 56% at least 3. The maximal number of errors was 38. Further, the errors analysis showed that 85% of the errors had been repeated (e.g. reproduced on several days). Finally, the more complex the drug prescriptions are, the higher the error rate is. No other variable (age, gender, level education, habit of filling a pillbox) had any effect on the number of errors. So, the pillbox filing task can be considered as a complex task associated with a high risk of errors. Moreover, the absence of cognitive disorders is not a success factor to the task. A prospect for the future should be to try to limit the error rate by developing, for instance, an external support helping to the filling of the pillbox and a learning process for the use of this support.