Subitizing
The term refers to the sensation of instantly knowing how many objects are in the visual scene when their number falls within the subitizing range.
However, the relative differences in costs associated with enumerating items within the subitizing range are small, whether measured in terms of accuracy, confidence, or speed of response.
[13] Together, these findings support the idea that subitizing is a general perceptual mechanism extending to auditory and tactile processing.
Atkinson, Campbell, and Francis[16] demonstrated that visual afterimages could be employed in order to achieve similar results.
[19] Social theory supporting the view that subitizing and counting may involve functionally and anatomically distinct brain areas comes from patients with simultanagnosia, one of the key components of Bálint's syndrome.
[23] The disorder is associated with bilateral damage to the parietal lobe, an area of the brain linked with spatial shifts of attention.
[18] These neuropsychological results are consistent with the view that the process of counting, but not that of subitizing, requires active shifts of attention.
[18][19] Such research finds that within the subitizing and counting range activation occurs bilaterally in the occipital extrastriate cortex and superior parietal lobe/intraparietal sulcus.
In the twentieth century, mathematics educators started to adopt some of these systems, as reviewed in examples below, but often switched to more abstract color-coding to represent quantities up to ten.
[22] A more recent meta-study summarizing five different studies concluded that infants are born with an innate ability to differentiate quantities within a small range, which increases over time.
[citation needed] The hypothesized use of yupana, an Inca counting system, placed up to five counters in connected trays for calculations.
Recognizing such visual or tactile representations and associating quantities with them involves different mental operations from subitizing.
For example, writing one million (1000000) as 1,000,000 (or 1.000.000 or 1000000) or one (short) billion (1000000000) as 1,000,000,000 (or other forms, such as 1,00,00,00,000 in the Indian numbering system) makes it much easier to read.
Dice, playing cards and other gaming devices traditionally split quantities into subitizable groups with recognizable patterns.
