About the Authors
Dipartimento di Psicologia, Università di Firenze, Firenze, Italy
Istituto di Neuroscienze del Consiglio Nazionale delle Ricerche, Pisa, Italy
The authors have declared that no competing interests exist.
SB and DCB conceived and designed the experiments. SB and NM performed the experiments and analyzed the data. SB and DCB wrote the paper.