This article in the Review of Development Economics, presents the results of a quantitative analysis that measured the relationship between psychosocial status at the age of 8, and the development of cognitive skills four years later. The data were taken from 700 Peruvian children who completed the Peabody Picture Vocabulary Test and the Raven's Progressive Matrices. These two tests provided scores for cognitive skill achievement.

A journal article titled Migration from Rural to Urban Areas and Vocabulary Development by María Cristina Vásquez Bendezú has been published in Revista Peruana De Investigacion Educativa, 9: 199-22..

Abstract:

Using data from the Peruvian sample of the Young Lives study, this paper investigates the association between maternal group participation and child nutritional status at the ages of 1 and 5 years. This study finds that the relationship between child nutrition and maternal group participation depends on the level of maternal education. In fact, maternal group participation is positively associated with child height‐for‐age when children were 1 year old, for those children whose mothers had had no formal education. This same association fades at 5 years of age.