The study included 386 kindergarteners from schools in the Fast Track Project, a multi-site clinical trial in the U. S. that in 1991 began tracking how children developed across their lives.

这项研究包括了386名来自“快速通道”项目的幼儿园儿童。“快速通道”项目是美国的一个多地点临床试验项目，从1991年开始追踪儿童一生的发育情况。