Genetic influences on human conditionability: A twin study of the conditioned eyeblink response

Acquisition of the classically conditioned eyeblink response is generally r egarded as one of the most basic forms of associative learning. A great dea l is known about how the brain encodes this simple form of learning, so tha t performance of this task may be an indirect indicator of brain functionin g. Individual differences in response acquisition have been revealed, but l argely ignored, in the research literature. We tested the temporal stabilit y and familial origins of these individual differences using a classic twin study design. Results reveal substantial individual differences in acquisi tion of the conditioned eyeblink response. These differences are stable acr oss brief retest, and differences in response acquisition exhibit familial aggregation, apparently due, in part, to genetic resemblance.