1. a National Technical Institute for the Deaf, Rochester Institute of Technology , USA
2. e Center for Research, Teaching, and Learning, National Technical Institute for the Deaf , 52 Lomb Memorial Drive, Rochester, NY, 14623, USA E-mail:
3. b University of Padova , Italy
4. f Dipartimento di Psicologia Generale , Università di Padova , Piazza Capitaniato 3, Padova, 35139, Italy
5. c University of North Carolina at Greensboro , USA
6. d University of Padova , Italy