Articulatory suppression effects on short-term memory of signed digits and lexical items in hearing bimodal-bilingual adults

We can gain a better understanding of short-term memory processes by studying different language codes and modalities. Three experiments were conducted to investigate: (a) Taiwanese Sign Language (TSL) digit spans in Chinese/TSL hearing bilinguals (n = 32); (b) American Sign Language (ASL) digit spans in English/ASL hearing bilinguals (n = 15); and (c) TSL lexical sign spans in Chinese/TSL hearing bilinguals (n = 22). Articulatory suppression conditions were manipulated to determine if participants would use a speech- or sign-based code to rehearse lists of signed items. Results from all 3 experiments showed that oral suppression significantly reduced spans while manual suppression had no effect, revealing that participants were using speech-based rehearsal to retain lists of signed items in short-term memory. In addition, sub-vocal rehearsal using Chinese facilitated higher digit spans than English even though stimuli were perceived and recalled using signs. This difference was not found for lexical sign spans.