We show that children with ASD have lower overall quality of handwriting related to motor difficulties that may impede the proper formation of letters. While their overall quality is worse, children with ASD are able to align, size, and space their letters as well as control children.
Despite its inherent qualitative nature, the Minnesota Handwriting Assessment has been praised as a strong tool for evaluating handwriting. The test yields both high interrater and intrarater reliability.23
Furthermore, detailed training and practice scoring provided by the manual, as well as the use of ruler measurements to guide scoring, uniquely improve assessment. In a review of handwriting tests, the Minnesota Handwriting Assessment was described as a tool that “is easy to score and administer and yields a more quantitative result than most handwriting assessments.”28
The test also has strong construct validity, successfully predicting subjects who are subjectively labeled by their teachers as having “good” or “bad” handwriting.1
We found that individuals with ASD were not worse than control subjects at aligning their letters on the specified lines or sizing their letters to match the sample. These features are specified in the task directions and are the most dependent on attending to the task. The lack of difference in performance within these realms strongly suggests that the ASD group attended to the task’s directions as well as the control group.
Although there was no difference in rate scores between the ASD and control groups, we cannot conclude that children with ASD write at the same rate as control children. In line with the Minnesota Handwriting Assessment scoring, subjects only began to lose points for rate if they did not complete the test within 2.5 minutes. Almost all subjects (10/12 control, 9/12 ASD) completed the test within the time limit, so we cannot assess rate differences within these subjects (e.g., a subject who took 1 minute to complete the test received the same rate score as a subject who took 2 minutes). Rather than setting a predetermined time limit, future studies should look for group differences in average time for completion.
Previous studies have found that individuals with autism are perceptually biased toward local features, as opposed to control subjects, who are biased toward global features. The Block Design test is a classic task used to demonstrate this bias, as subjects with ASD reproduce the patterns more quickly than control subjects.27,29–32
It is hypothesized that this superior performance is linked to an improved ability to segment the patterns (i.e., see the local components) and in turn more easily construct the patterns from smaller pieces. We hypothesized that visuospatial biases may influence handwriting by affecting subjects’ visual representations of letters. We found, however, that visual biases, as determined by Block Design scores, did not predict handwriting performance. Since our methods only analyzed the completed handwriting sample, it is possible that visual biases for local features may have influenced the strategy of individuals with ASD. This possibility is supported by a study that showed that when boys with ASD copied drawings of objects they were more likely than controls to begin by drawing local features rather than the overall outline and they tended to continue drawing in a piecemeal fashion.12
Individuals with ASD may use a more local strategy for drawing letters, or it is possible that letters are so commonly viewed that they are visually processed more automatically, not requiring the build up of local features into a whole that more novel visual stimuli require. This seems likely given that our subjects were all fluent readers. Either way, within our sample the final quality of handwriting was not affected by visuospatial biases. Other senses, such as proprioception, were not examined; how other sensory issues contribute to handwriting in autism should be examined in future studies.
A number of studies have demonstrated that individuals with autism have problems with motor functions.4–7
The PANESS in particular has been used to demonstrate basic motor impairments in children with ASD relative to controls.4,25,26
Consistent with these results, our ASD group scored significantly worse on the PANESS than our control group, demonstrating general motor impairments.
Unlike visuospatial abilities, within the ASD group motor performance predicted overall handwriting quality, as well as performance within a number of the assessment’s subcategories, suggesting that general difficulties with motor control contribute to lower quality handwriting. These results suggest that without steady motor control one cannot accurately and fluidly control hand and arm movements. Asperger noted such a relationship when commenting on one of his original patients: “this motorically clumsy child had atrocious handwriting ... The pen did not obey him.”3
Within the PANESS, performance on timed movements—the movements requiring the greatest fine motor control—was specifically linked to handwriting performance, which corroborates findings suggesting a relationship between complex finger movement abilities and handwriting.33
No such relationship was found within the control group, likely due to the group’s lack of variability in scores. While within the control group girls performed better than boys in some categories, no gender difference was found within the ASD group, possibly due to motor impairments overshadowing gender effects.
Performance in form observed in our ASD group, which had an average age of 10.2 years, is below that previously reported in younger typically developing children: “somewhat below average” 6- to 7-year-olds scored between 25 and 29 and 7- to 8-year-olds between 28 and 30.22
Despite being older than these groups and being intelligence matched to our older control group, our subjects with ASD averaged a form score of only 24. This suggests that handwriting impairments in children with autism do not simply reflect a developmental delay. These results are only generalizable to individuals of average intelligence whose primary deficit is autism.
Our finding that subjects with ASD did not size their letters differently than controls is inconsistent with the previous result that adults with ASD demonstrate macrographia, sizing letters larger than controls.17
In our task, however, instructions specified that letter size match the sample, while in the previous study size was not specified. Furthermore, given that the previous study was performed in adults, subjects may have learned to draw letters larger to compensate for difficulties with fine motor control. Our younger subjects may not yet have adapted this strategy or could not use it given that the task instructions specified letter size. Even within the adults study, the authors commented that many handwriting samples from subjects with ASD were subjectively hard to read, and they speculated that this poorer quality and macrographia were related to motor coordination impairments.
While unable to use a compensatory sizing strategy, observations suggest that our ASD subjects exhibited other compensatory motor techniques. For example, 2 of the highest scoring subjects with ASD gripped their dominant forearms with their nondominant hands to help steady their movements, a strategy they were taught in school. These observations, in combination with the result that motor abilities strongly predict handwriting performance, suggest that therapies targeting motor control are the best approach to improving handwriting in individuals with autism.