Mental development as related to institutional and foster home placement.

Until comparatively recently, general intelligence was regarded as innately fixed, unmodifiable and relatively unaffected by environmental factors. However, results of research undertaken during the past two decades suggest that the intelligence of children may undergo modification under certain gross environmental conditions, in accordance with certain general and fairly clear principles. Although much more experimentation and investigation are necessary to supplement existing data, and although the tools of measurement require revision before any sound conclusions can be arrived at, one must be willing to accept the fact, that intelligence is possibly more plastic and modifiable than has hitherto been believed possible. [...