In one task-switching experiment, we compared bilinguals and monolinguals to explore the reliability of the bilingualism effect on the n-2 repetition cost. In a second task-switching experiment, we tested another group of bilinguals and monolinguals and measured both the n-1 shift cost and the n-2 repetition cost to test the hypothesis that bilingualism should confer a general greater efficiency of the executive control functioning. According to this hypothesis, we expected a reduced n-1 shift cost and an enhanced n-2 repetition cost for bilinguals compared to monolinguals. However, we did not observe such results. Our findings suggest that previous results cannot be replicated and that the n-2 repetition cost is another index that shows no reliable bilingualism effect. Finally, we observed a negative correlation between the two switch costs among bilinguals only. This finding may suggest that the two groups employ different strategies to cope with interference in task-switching paradigms.
