Kareev Y
Goldie Rotman Center for Cognitive Science and Education, School of Education, Hebrew University of Jerusalem, Israel.
Cognition. 1995 Sep;56(3):263-9. doi: 10.1016/0010-0277(95)92814-g.
The samples of data that people use in their attempts to detect relationships in the environment are limited in size by working memory capacity. The implications of that constraint are explored by analyzing the sampling distribution of the most common measure of relationship--the product moment correlation (Pearson's rxy). This distribution is skewed when the population correlation differs from zero (i.e., when a correlation exists), and the more so, the smaller the sample. As both the median and the mode of the sampling distribution are more extreme than the population value, it follows that samples likely to be encountered indicate a correlation stronger than that in the population. Thus, the limited capacity of working memory may serve as an amplifier that helps people to avoid missing strong relationships. As the distribution is more skewed the smaller the sample size, the effect suggests an explanation for the fact that young children detect meaningful covariation fairly rapidly.
人们在试图发现环境中的关系时所使用的数据样本，其大小受到工作记忆容量的限制。通过分析关系的最常见度量——积差相关（皮尔逊rxy）的抽样分布，来探究这一限制的影响。当总体相关不为零时（即存在相关性时），这种分布是偏态的，样本越小，偏态越明显。由于抽样分布的中位数和众数都比总体值更极端，因此可以得出，可能遇到的样本表明的相关性比总体中的更强。因此，工作记忆的有限容量可能起到一个放大器的作用，帮助人们避免错过强关系。由于样本量越小，分布的偏态越明显，这一效应为幼儿能相当迅速地发现有意义的协变这一事实提供了解释。
