From “nine hundred and two” to 90,02: syntactic processes in number writing and their impairment
Read the full dissertation (in Hebrew)…
Writing numbers to dictation is a fundamental aspect of numerical literacy and mastering it among young children predicts success in future arithmetic skills. Despite the importance of this ability, it has not been sufficiently studied and the exact nature of the cognitive processes underlying it is still unclear.
Previous studies reported dissociations between verbal input processes and digit production processes; and between lexical processes, which handle single words/digits, and syntactic processes, which handle the relation between lexical elements. However, the precise cognitive organization of number writing is still poorly understood – in particular, we do not know whether the syntactic/lexical distinction exists also within specific processing stages. The aim of the present study was to understand the cognitive mechanisms involved in writing numbers to dictation; specifically, we examined whether we can identify syntactic mechanisms specifically in the verbal-input level and in the digit-production level.
We report 4 women with dysnumeria, a deficit in processing symbolic numbers (digits / number words), who had many syntactic errors when writing numbers to dictation. In order to find the origin of their syntactic errors, we assessed in detail their performance in a series of tasks, each involving different sub-process of writing numbers to dictation. For two of the women, the origin of the syntactic errors was a selective deficit in syntactic processing at the verbal-input level, with spared digit output mechanisms. The two other women showed an opposite pattern: a selective deficit in syntactic processing at the digit-production level, with spared verbal input.
This double dissociation shows that both the verbal input mechanisms and the digit-production mechanisms are divided into lexical and syntactic processes. Based on this and previous findings, we propose a comprehensive cognitive model for number writing. The model postulates separate mechanisms for verbal input and for digit production, and a distinction between lexical and syntactic processes in each of them. It also suggests additional, hypothetical components whose existence has not yet been empirically tested.
Along with the cognitive importance of this study, it also emphasizes the importance of accurate diagnosis of the precise origin of the difficulty in processing numbers and specifically in writing numbers. The study also presents a battery of tests for detailed cognitive assessment of number writing abilities. Finally, the study emphasizes a number of methodological principles that should be considered when assessing number writing abilities – foremost, considering the participant’s memory capacity and their use of strategies as potential confounding factors.