Procedure
The experiment lasted for two sessions scheduled during the same week. Each session was composed of 12 blocks of 50 trials (for a total of 600 trials). In Session 1, half the
participants in each condition were trained in the direct classification task, while the remaining participants were trained in the same–different categorization task. The task practiced during Session 1 was called the training task. In Session 2, the first two blocks (100 trials) were done in the training task. The remaining 10 blocks (500 trials) were done in the other (unpracticed) task with the same category structures. This second task was called the transfer task. The participants were told that the same categories were used in the training and transfer tasks. The procedure for the same–different categorization task was identical to that of Experiment 1. For the direct classification task, participants were told they were taking part in a categorization experiment and that they had to assign each stimulus into either an ‘‘A’’ or a ‘‘B’’ category. A trial went as follows: a fixation point (crosshair) appeared on the screen for 1,500 ms and was followed by the stimulus, which remained on the screen until the participant made a response; correct or incorrect auditory feedback was given
for 1,000 ms; ‘‘Wrong Key’’ or ‘‘Too Slow’’ feedback was given for 2,000 ms. The participants were allowed to take a break between blocks if they wished.