Weinstein, Przybylski & Ryan, 2012.
A growing interest in the functional importance of dispositional autonomy led to the development and validation of the Index of Autonomous Functioning (IAF) across seven studies. The IAF provides a measure of trait autonomy based on three theoretically derived subscales assessing authorship/self-congruence, interest-taking, and low susceptibility to control. Results showed consistency within and across subscales, and appropriate placement within a nomological network of constructs. Diary studies demonstrated IAF relations with higher well-being, greater daily satisfaction of basic psychological needs, and more autonomous engagement in daily activities. Using an experimental approach, the IAF was shown to predict more positive interactions among dyads. The studies provided a systematic development and validation of a measure of autonomy that is brief and reliable.
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Full reference: Weinstein, N., Przybylski, A. K., & Ryan, R. M. (2012). The index of autonomous functioning: Development of a scale of human autonomy. Journal of Research in Personality, 46(4), 397-413.