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A battery of cognitive tests was administered by telephone to 194 pairs of MZ and DZ twins: 112 pairs reared apart and 82 pairs reared together. The six measures, chosen to identify known intelligence and short-term memory factors, included two marker variables for crystallized intelligence (information and synonyms), two markers for fluid intelligence (analogies and figure logic), and two markers for short-term memory (forward and backward digit span). The data provide support for the feasibility of substituting telephone testing of abilities for more traditional assessment procedures.
Nesselroade et al. (Wed,) studied this question.