Reading comprehension and mental subtraction in deaf and hard of hearing children: the moderating role of grade level

Prior studies have documented an association between reading comprehension and arithmetical skills. However, the underlying processes that might moderate these associations, particularly while accounting for general cognitive abilities, remain unclear. This study investigated whether grade level moderated the relationship between reading comprehension and mental subtraction in deaf and hard of hearing (DHH) children, after controlling for intelligence. A sample of 257 DHH children from Grades 3 to 9 in China completed measures of reading comprehension, single-digit subtraction, double-digit subtraction, and a test of non-verbal intelligence. Results indicated that after controlling for intelligence, the direct effect of reading comprehension on subtraction performance was not significant. However, moderation analyses using the PROCESS macro revealed that grade level significantly moderated this relationship for both single-digit and double-digit subtraction. Simple slope analyses showed that for children in higher grades, reading comprehension was a strong and significant predictor of subtraction performance. In contrast, for children in lower grades, the association was significantly weaker for single-digit subtraction and non-existent for double-digit subtraction. These findings highlight grade level as a critical developmental moderator, suggesting that the role of reading comprehension in arithmetic emerges and strengthens in later school years among DHH children.