Universität Freiburg, AG Optomotorik

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

Author: Burkhart Fischer, Dipl. Phys., Christine Gebhardt, Dipl. Phys., and Klaus Hartnegg, Dipl. Phys.

Organiszation: Centre of Neuroscience, Optomotor Laboratory, University of Freiburg, Freiburg, Federal Republic of Germany

Journal: Optometry & Vision Development 39: 1 (2008)



The ability of recognizing a number of briefly presented items without actually counting is called subitizing (from lat. subito = suddenly). Adult subjects can subitize 3 to 4 items. For greater numbers the subjects begin a counting process relying on the visual memory of the test pattern, which needs increasingly more time as the number of items increases. The development of accuracy and speed of subitizing and visual counting was measured for subjects up to the age of 17 years. Furthermore, this study tests the hypothesis that children with difficulties in acquiring basic arithmetic skills exhibit developmental deficits in subitizing and/or counting. The study does not intend to investigate theories on the nature of dyscalculia even though most test children can be classified as dyscalculic.

Methods: Two-hundred-nineteen control subjects and 156 test subjects with problems in arithmetic skills in the age range of 7 to 17 years were given a visual counting task in which 1 to 9 items were presented for 100 ms. The subjects had to press a digit key on a numerical keyboard to indicate the number of items they had seen. Percentages of correct responses and response times were recorded.

Results: The analysis shows systematic differences between control and test children increasing with age. The percentage of test children performing below the 16-percentile of the age matched controls was estimated to be between 40% and 78% (increasing with age).

Conclusions: We concluded that the deficit in a basic visual capacity may contribute to the problems encountered by children with anomalies in acquiring basic arithmetic skills.

Keywords: subitizing, visual number counting, dyscalculia, saccades

More: full text (PDF, 1.7 MB)

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