Effect of memory support and elicited production on fast mapping of new words by adolescents with Down syndrome

Purpose: The purpose of this study was to determine whether memory support and elicited production differentially benefited fast mapping of new vocabulary (comprehension, production accuracy, and speed) in adolescents with Down syndrome (DS) compared with typically developing (TD) children matched for syntax comprehension. The study also examined predictors of individual difference within groups. Method: The ability of 19 adolescents with DS to fast map new noun vocabulary was compared with 18 TD children matched for syntax comprehension. The effects of memory support (5 examiner repetitions of the novel word vs. 1) and elicited production (2 repetitions by child vs. none) were evaluated in a repeated-measures design with counterbalancing of tasks. Results: For novel word comprehension, low memory support impaired the TD but not DS participants. DS participants were slower to respond correctly in all conditions but benefited more from memory support than TD participants in speed of response. For novel word production, high memory support benefited all participants in the no-elicited-production condition. Elicited production improved performance equally in the 2 memory conditions. Standard comprehension measures predicted fast-mapped comprehension: vocabulary in the case of the DS group, syntax in the case of the TD group. Auditory short-term memory measures predicted fast-mapped production in the TD group but not the DS group. Hearing and grammatical morpheme comprehension predicted novel word production in the DS group. Conclusions: DS participants' speed of comprehension of fast-mapped words was differentially increased compared with the TD syntax-comprehension-matched group, by memory support. Elicited production improved production fast-mapping for all participants, and memory support improved it in the absence of elicited production. Comprehension predicted individual differences in fast-mapped comprehension in DS; in addition, hearing predicted production.