A 51-item fear survey was administered to more than 2,600 adolescents and adults, including m ore than 400 pairs of like-sex twins, to examine developmental patterns and genetic influences on common fears. Raw data were age-sex standardized and subjected to factor analysis, and preliminary analyses of the factor scores documented both age and genetic effects. Some fears habituate with age; others exhibit sensitization; and, for some fears, intensity is uniform across development. Genetic effects were found for all factors, but the magnitude of such effects varied. Based on these initial analyses, developmental patterns of genetic and environmental influences on self-assessed fears were examined in 354 pairs of like-sex twins, ages 14-34. Hierarchical multiple regression was used to predict a twin's fearfulness from the co-twin's fear, the age and zygosity of the twin pair, and the interactions of these 3 predictors. For all fear factors, co-twin's score and the interaction of co-twin's score with pair zygosity significantly contributed to the prediction of a twin's fearfulness, but the magnitude of both effects varied for different fears. For 2 fear factors, Personal Death and Loved One's Misfortunes, 3-way interactions of co-twin's score, age, and zygosity were observed. The findings suggest significant genetic modulation of developmental patterns in the acquisition and maintenance of some adaptive fears.

A 51-item fear survey was administered to more than 2,600 adolescents and adults, including m ore than 400 pairs of like-sex twins, to examine developmental patterns and genetic influences on common fears. Raw data were age-sex standardized and subjected to factor analysis, and preliminary analyses of the factor scores documented both age and genetic effects. Some fears habituate with age; others exhibit sensitization; and, for some fears, intensity is uniform across development. Genetic effects were found for all factors, but the magnitude of such effects varied. Based on these initial analyses, developmental patterns of genetic and environmental influences on self-assessed fears were examined in 354 pairs of like-sex twins, ages 14-34. Hierarchical multiple regression was used to predict a twin's fearfulness from the co-twin's fear, the age and zygosity of the twin pair, and the interactions of these 3 predictors. For all fear factors, co-twin's score and the interaction of co-twin's score with pair zygosity significantly contributed to the prediction of a twin's fearfulness, but the magnitude of both effects varied for different fears. For 2 fear factors, Personal Death and Loved One's Misfortunes, 3-way interactions of co-twin's score, age, and zygosity were observed. The findings suggest significant genetic modulation of developmental patterns in the acquisition and maintenance of some adaptive fears.

Three experim^ite (total N = 102) are reported which examined the relationship between individual differraices in ability to ccmtrol heart rate (HR) with feedback and differoices in self-reported cognitive strategies, personality variables (locus of control, state and trait anxiety), physiolc^cal variables (respiraticm, somatic »:tivity, basal HR and HR variability, and initial ability to control HR without feedback), and several auxiliary variables (e.g., weight, smoking, gender, exercise, and meditation). Two sets of analyses were perfdHined. In the first set, differences in copiitive strategies and physiological concomitants between HR decrease and HR increase were studied revealing disparate patterns of cognitive strat^es and physiological concomitants for the two directions of HR control. In the second set, the grmip of cognitive, strat^y, personality, physiological, and auxiliary variables was searched to determine if any variables were related to individual differences in ability to decrease or increase HR. C(^nitive strategies, personality, and auxiliary variables were generally unrelated to ability to control HR in either direction. Use of two cognitive strat^es was found to be associated with lack of ability to increase HR, and non-smokers were better able to decrease HR. Strcmg relationships were found for somatic activity and ability to control HR without feedback, botih of which successfully predicted differ^ices in ability to decrease and increase HR witii feedback. Implications of these findings for past and future studies of voluntary control of HR are discussed. addressed methodological and parametric issues which were also well suited to analysis using group data. These issues, comprehensively reviewed by Williamson and Blanchard (1979), included effects of extended training, various feedback parameters, subject motivation, and knowledge of feedback contingencies.Emergence of the current emphasis on individual differences may reflect a growing dissatisfaction with the amount of new knowledge generated from the large number of studies of voluntary control of HR. Regardless, choice of an individuai difference methodology has potential for asking new research questions and generating new kinds of data. The purpose of the present report is to examine the relationship between ability to control HR and a number of potentially relevant variables. Our research question can be stated quite simply: what characteristics differentiate people who differ in ability to control HR? As Williamson and Blanchard's (1979) review indicates, this question has been addressed in terms of several psychological (e.g., locus of control, anxiety) and physiological 91