Subitizing and Visual Counting in Children with Problems in Acquiring Basic Arithmetic Skills

ABSTRACTThe ability of recognizing a number of brieflypresented items without actually counting is calledsubitizing (from lat. subito = suddenly). Adult subjectscan subitize 3 to 4 items. For greater numbers thesubjects begin a counting process relying on the visualmemory of the test pattern, which needs increasinglymore time as the number of items increases. Thedevelopment of accuracy and speed of subitizingand visual counting was measured for subjects up tothe age of 17 years. Furthermore, this study tests thehypothesis that children with difficulties in acquiringbasic arithmetic skills exhibit developmental deficits insubitizing and/or counting. The study does not intendto investigate theories on the nature of dyscalculiaeven though most test children can be classifiedas dyscalculic.Methods: Two-hundred-nineteen control subjectsand 156 test subjects with problems in arithmetic skillsin the age range of 7 to 17 years were given a visualcounting task in which 1 to 9 items were presentedfor 100 ms. The subjects had to press a digit key on anumerical keyboard to indicate the number of itemsthey had seen. Percentages of correct responses andresponse times were recorded.Results: The analysis shows systematic differencesbetween control and test children increasing with age.The percentage of test children performing belowthe 16-percentile of the age matched controls wasestimated to be between 40% and 78% (increasingwith age).Conclusions: We concluded that the deficit in abasic visual capacity may contribute to the problemsencountered by children with anomalies in acquiringbasic arithmetic skills.