The performance on a battery of cognitive tests of an individual with extraordinary ability at mental arithmetic was studied. Implications of the rather ordinary test performance of Shakuntala Devi in contrast with her calculating speed are discussed with reference to memory and information processing. (SLD)

The hypothesis that a task that increases in complexity (increasing its correlation with a central measure of intelligence) does so by increasing its dimensionality by tapping individual differences or another variable was supported by findings from 46 adults aged 20-70 years performing a mental counting task. (SLD)