ERIC Number: ED027058
Record Type: RIE
Publication Date: 1966-Apr
Reference Count: 0
Further Evidence on the Relation Between Age of Separation and Similarity in IQ Among Pairs of Separated Identical Twins.
Vandenberg, Steven G.; Johnson, Ronald C.
Ronald C. Johnson argued that if early environmental stimulation or deprivation has a significant effect on intellectual ability, then individuals who are genetically identical and who are exposed to a common early environment should resemble one another more closely in IQ than similar individuals who have not shared a common environment. Johnson compared the IQ's of 23 pairs of twins separated at different times. He found that twins who were separated after they were 1 year old resembled one another significantly less closely than early separated twins. A Danish study of 12 pairs of Juel-Nielsen (1962) supported this result. A study by Shields in 1962 found no significant difference in the scores of 48 pairs of twins on (1) Raven's Dominoes Intelligence Test and (2) the synonyms part of the Mill Hill Vocabulary Scale, regardless of the age of the pair of separation. (WD)
Publication Type: N/A
Education Level: N/A
Sponsor: National Institutes of Health (DHEW), Bethesda, MD.
Authoring Institution: Colorado Univ., Boulder.; Louisville Univ., KY. School of Medicine.
Identifiers: D48 Test; Mill Hill Vocabulary Scale