- Joined Aug 27, 2009
The fact that newborn chicks, fish and human neonates can make numerical discriminations suggests that this capacity does not arise as a result of interaction with the environment, but is inherited though subsequent interaction with environment doubtless modifies and refines the operation of this mechanism. It is also the case, as Butterworth  points out, that individual differences in numerical abilities have a substantial genetic component, perhaps as much as 30% of the variance in systematic twin studies. This suggests that the starter kit for learning arithmetic in school includes a domain-specific mechanism for representing numerosities, and that individual differences in this mechanism may explain why about 5% children (and adults), despite good formal education, have such trouble in learning arithmetic (though not necessarily other branches of mathematics, such as geometry). There is now an extensive literature linking poor numerosity discrimination or identification with poor arithmetical competence, even when other cognitive factors are taken into account. Burr et al.  suggest that of their three mechanisms, it is the enumeration mechanism that is most closely linked to arithmetical competence.