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 taskswitching 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.

We are grateful to Dr. Kenneth Paap and Dr. Mireia Hernández for their useful comments on the previous versions of this manuscript. This work was supported by grants from the Spanish Government (PSI2014-54500, PSI2008-01191, PSI2011-23033, PSI2014-53427-P, Consolider Ingenio 2010 CSD2007-00012), the Catalan Government (Consolidat SGR 2009-1521 and SGR 2014-1210), by one grant from the European Research Council under the European Community’s Seventh Framework (FP7/2007-2013 Cooperation grant agreement 613465-AThEME), by one grant from Fundación Séneca (19267/PI/14) and by the Severo Ochoa program grant SEV-2015-049. Francesca M. Branzi was supported by a predoctoral fellowship from the Spanish Government (FPU-2009-2013) and by a postdoctoral fellowship from the European Union’s Horizon 2020 research and innovation programme, under the Marie Sklodowska-Curie grant agreement No 658341. Marco Calabria was supported by a postdoctoral fellowship from the Spanish Government (Ramón y Cajal Fellowship).