Does the raising IQ-raising g distinction explain the fadeout effect?

摘要

Previous investigations into raising IQ show that after an intervention ends, the effects fade away. This paper is an attempt to understand one possible reason for this fadeout; the idea that the effects fade because they were not to the underlying construct g. A large (N = 985) randomized controlled trial is re-analyzed to investigate whether the intervention, which began at birth and lasted for the first three years of the children's life, raised the underlying cognitive factor of IQ tests. This was done under strict measurement invariance. The intervention indeed raised the g factor at age three. No effects were seen at follow-up assessments at ages five and eight after the intervention ended. Therefore, the raising IQ/raising g distinction is insufficient as an explanation for the fadeout effect, as changes to the environment can improve g and still fade. (C) 2016 Elsevier Inc. All rights reserved.