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 (Weinstein, Przybylski, & Ryan, 2012). The IAF provides a brief and reliable measure of trait autonomy based on three theoretically derived subscales assessing authorship/self-congruence, interest-taking, and low susceptibility to control. Initial validation studies 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. Please note that when using the subscales separately, the interest-taking subscale is still in exploratory phase of validation.
(2012) Journal of Research in Personality