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Subitizing in Arithmetic

Even simple arithmetic tasks require that the subject has developed a sense of number. Following the hypothesis of teachers It was suspected that children with specific difficulties In learning basis arithmetic may not have developed this sense, because they could not use the special visual capacity of subitizing. Subitizing is a process, which allows a subject to know immediately, how many items they have seen, even the items were presented for 100 ms only. As long as the number of items remains below 4 the time needed to tell how many were presented Is constant. For higher numbers of Items one needs more time. When calculating the velocity of this process and plots It as a function of age, on arrives at tow different curves depending on whether normal children or children with problems in earning basic arithmetic were assessed. The right side shows the percentage of children, who failed to reach the range of the controls by more than one standard deviation.


The age curves of the velocity of correct number counting are different for normal control children and children with specific problems In learning basic arithmetic (dyscalculics). The right side shows the percenatge of dyscaculics, who did not reach the range of the controls.

Successful training of subitizing and transfer to arithmetic and number counting by memory improves the basic number operations required in school.

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