The importance of non‐verbal skills in the acquisition of place‐value knowledge: Evidence from normally‐developing and language‐impaired children

Abstract

Children's comprehension of the Hindu‐Arabic number system was explored in relation to their ability to match spoken to Hindu‐Arabic numerals. The possible involvement of verbal processes in numeric understanding was examined by comparing a group of 8‐year olds with specific language impairments (SLI group, N = 13) to two control groups, the first matched for age and non‐verbal ability (AC group, N = 13), the second younger group matched for language comprehension level (LC group, N = 12). SLI, AC and LC children's accuracy and efficiency in choosing the greater of two single‐digit Hindu‐Arabic numerals were compared. One child from the SLI group and three from the LC group failed to reach accuracy criterion. For accurate responders there was no difference between SLI and AC groups in latency to judge: both responded faster than the LC group. When making judgments all groups showed the Symbolic Distance Effect observed by Moyer & Landauer (1967). All participants were able to match spoken numerals to Hindu‐Arabic single‐digit numerals without error. SLI and AC groups were tested on double digits. Accuracy and efficiency in judging the greater of two Hindu‐Arabic double‐digit numerals were tested. Ability to match spoken numerals to corresponding double‐digit Hindu‐Arabic numerals was also tested. All of 12 AC participants accurately matched spoken to Hindu‐Arabic symbols, but 2 of these were unable to judge accurately the greater of pairs of HinduArabic symbols. Of 13 SLI children tested, 9 accurately matched spoken to Hindu‐Arabic symbols; 2 of these were unable to judge Hindu‐Arabic symbols accurately. One further child was able to judge accurately but performed poorly when matching spoken to Hindu‐Arabic numerals. When school experience of doubledigit numbers was statistically controlled, there was no difference between SLI and AC groups in the accuracy of double‐digit judgments. No difference was found between SLI and AC groups in the speed or pattern of accurate responders’ doubledigit judgments. When group data was pooled and school experience statistically controlled, accuracy in double‐digit judgment was predicted by non‐verbal ability, but not by expressive or receptive language skills. The pattern of responses to the double‐digit judgments suggested a ‘holistic’ processing mechanism within which ‘transparent’ stimuli (those double digits which minimize conflict between ‘face’ and ‘place’ values) are most rapidly encoded. Whereas the ability to match verbal labels to Hindu‐Arabic numerals appears generally to precede single‐ and double‐digit comprehension, findings suggest that, especially in the acquisition of place‐value knowledge, there is substantial autonomy of non‐verbal systems.