Beyond Subitizing: Symbolic Manipulations of Numbers

This study tested the hypothesis that subitizing ability may cause achievement differences in mathematics especially for students with mathematics learning disabilities. Students from 1st through 4th grade were applied to curriculum based math achievement tests (MAT). Based on MAT scores, they were divided into four groups as Mathematics Learning Disorder (MLD) risks, low achievers (LA), typical achievers (TA), and high achievers (HA). All students were asked randomly and canonically arranged dot enumeration tasks with 3 through 9 dots. Median response times (MRT) were calculated for each task and plotted for each grade level and task types. There were virtually no differences in MRTs for number 3 and 4. On the other hand, the MLD risk group spent relatively more time on enumerating canonically arranged dots from 5 through 9. Results provided more support for the claim that rather than subitizing, numerosity coding mechanisms or the type of symbolic quantity manipulations is different in children with different mathematical achievements especially the lower group, the MLD risk group