Abstract:

Visual-motor integration (VMI) refers to the coordination and integration of visual perception and fine motor skills, requiring individuals to perceive visual inputs and then plan and execute muscle movements accordingly. Numerous studies have shown that VMI ability is closely related to reading, with the degree of correlation being age-dependent. The development trajectory of the correlation between VMI ability and reading varies across different writing systems. In alphabetic writing systems, while the correlation between reading and VMI ability declines with age, it remains significant until secondary school. As for the reasons for this trend, considering the fact that as reading develops, the reliance on individually identifying letters and their order in words (which helps children sounding out the words) diminishes, giving way to a more automated process of direct retrieval. Consequently, the influence of VMI ability on reading performance diminishes with age. In Chinese writing system, mainland readers use simplified Chinese characters, while Hong Kong readers use traditional Chinese characters with more complex morphological structures (for example, the simplified Chinese character for tree is “树” and the traditional Chinese character is “樹”). Studies have shown that the correlation between simplified Chinese character reading and VMI ability increases with age, reaching a significant correlation in the upper grades of primary school (9 years and older). The lack of significance in the correlation between the two variables at a younger age may be attributed to the limited exposure of literacy instruction among younger children. During this developmental stage, there might not yet exist a stable correlation between their underdeveloped VMI ability and difficult Chinese character reading. For the traditional Chinese characters, there is a significant correlation between reading and VMI ability in preschool children. This difference in Chinese writing system can be attributed to the relatively easier nature of recognizing traditional Chinese characters and the relatively earlier literacy instruction received by Hong Kong children. Based on these reasons, their extensive practice in handwriting (which is the main way of learning Chinese characters) enhances their VMI and reading skills at a faster rate compared to mainland children. Consequently, a stronger correlation between VMI ability and reading may have been established among pre-school children in Hong Kong as opposed to those on the mainland. Additionally, studies focusing on developmental dyslexia (DD) groups with delayed reading skills have found that younger individuals exhibit more significant VMI deficits than older individuals across alphabetic writing systems, aligning with the developmental trajectory observed in typically developing children. In addition, research conducted on Chinese writing system has primarily focused on primary school students and has revealed that younger individuals with DD may not exhibit VMI deficits while older ones do, aligning with the developmental trajectory observed in Chinese typically developing children. Overall, it is evident that the correlation between VMI ability and reading performance is influenced by age and writing system. In light of the limitations of existing research, 1) future studies should adopt a multifaceted approach to measure VMI ability encompassing both process-oriented and outcome-based assessments. Most of the measurement of VMI ability in existing studies predominantly focus on the outcome, but ignore the process information. On the one hand, emphasizing process information can help improve the differentiation of the evaluation. On the other hand, disaggregating VMI performance into subcomponents such as latency and fluency can help clarify more clearly how VMI ability is involved in reading. 2) The emphasis on whether VMI ability serves as an essential foundation for supporting reading development constitutes a crucial aspect for future research. Specifically, these investigations should encompass several key dimensions. Firstly, longitudinal studies targeting the VMI ability of early children without reading experience can be conducted to distinguish the development sequence of VMI ability and reading ability from the temporal dimension. Secondly, conducting training studies on typically developing children can help elucidating whether VMI ability serves as a foundational precursor for reading development. Finally, by utilizing DD children who lag behind in reading ability, future studies can explore whether reading lag may due to VMI deficits. 3) Future researches should focus on elucidating the behavioral and neural mechanisms underlying the correlation between VMI ability and reading and its development. With regard to the internal mechanism through which VMI ability influences reading, previous studies have proposed hypotheses such as “the theory of internal models”, “the stroke processing hypothesis”, and “the visual analysis hypothesis”; however, empirical evidence remains insufficient to substantiate these hypotheses. Concerning the neural mechanism by which VMI ability impacts reading, prior research has suggested that the posterior parietal cortex may play a pivotal role; nevertheless, further exploration and verification from a developmental perspective involving participants across various age groups are warranted.

Key words: visual-motor integration, reading, development, writing system