Cognitive and neuronal bases of expertise
This thesis examines the cognitive and neural bases of expertise. In so doing, several psychological phenomena were investigated-imagery. memory and thinking-using different tasks, and a variety of techniques of data gathering, including standard behavioural experiments, questionnaires, eye-movement recording, and functional magnetic resonance imaging (fMRI). Chess players participated in all the studies, and chess tasks were used. The data confirmed the versatility and power of chess as a task environment, since the results provided fruitful information for the understanding of different human cognitive processes. The role of practice in this domain of expertise was examined. The strong view that extended deliberate practice is a necessary and sufficient condition for the acquisition of expert performance, did not receive support in this thesis. Alternatively, a less extreme position was adopted: extended practice is a necessary, but not a sufficient condition for the acquisition of expert performance. A search for individual differences in factors unrelated to chess practice was carried out. The sources of these individual differences, as well as the cognitive abilities in which individual differences may exist, were considered. One of the sources-the age at which serious practice starts-was a good predictor of chess skill. Handedness, which is supposed to be determined by environmental factors in utero, slightly differentiated chess players from non-players, but no differences in this variable were found between strong and the weak players. Regarding the cognitive abilities, chess players performed slightly better than the non-chess players in a spatial task. Individual differences were also considered within a single leyel of expertise-master level. Differences in forgetting rate in long-term memory and reaction time were observed for one of the masters. These results contributed to the improvement of an extant theory of expertise-template/CHREST [CHunks and REtrieval STructures] theory-by estimating values for some of its parameters based on the empirical data obtained, and by proposing the addition of a spatial short-term memory.