Journal of Deaf Studies and Deaf Education Looking for an Explanation for the Low Sign Span. Is Order Involved?

Although signed and speech-based languages have a similar internal organization of verbal short-term memory, sign span is lower than word span. We investigated whether this is due to the fact that signs are not suited for serial recall, as pro-posed by Bavelier, Newport, Hall, Supalla, and Boutla (2008. Ordered short-term memory differs in signers and speakers: Implications for models of short-term memory. Cognition, 107, 433–459). We administered a serial recall task with stimuli in Italian Sign Language to 12 deaf people, and we compared their performance with that of twelve age-, gender-, and education-matched hearing participants who performed the task in Italian. The results do not offer evidence for the hypothesis that serial order per se is a detrimental factor for deaf participants. An alternative ex-planation for the lower sign span based on signs being pho-nologically heavier than words is considered. Starting from the seminal work by Bellugi, Klima, and Siple (1975), a considerable amount of evidence has been accumulated showing that signs are retained in short-term memory (STM) in a sign-based code, in analogy to the speech-based code used to retain verbal stimuli in spoken languages (Wilson & Emmorey, 1998). Notwithstanding these similarities, STM for words and signs differs in capacity, with an advantage for words. Sign span is lower than word span in pairs of different sign/spoken languages (Boutla, Supalla