The operationalization of self-identity in reasoned action models: a systematic review of self-identity operationalizations in three decades of research

Background: Self-identity has frequently been proposed as a useful addition to the Theory of Planned Behavior; yet Fishbein and Ajzen decided to not include self-identity when they published that theory’s successor, the Reasoned Action Approach. One of their reasons for exclusion is the lack of clear conceptual independence, as manifested in self-identity operationalizations that often conflate the construct with attitudinal or normative measures. Therefore, establishing whether self-identity has added value in the Reasoned Action Approach first requires synthesis of the used operationalisations to develop an operationalization that captures self-identity but not attitude and perceived norm. Method: In this systematic review we identified 153 articles through the PsycINFO database and descendency approach using Google Scholar. In total, 342 of the operationalisations of self-identity were identified in studies operationalizing it as a potential Reasoned Action Approach extension. Results and conclusions: After analyzing the full item pool to eliminate duplicates and items that did not measure selfidentity, (also) measured attitudes or norms, did not allow tailoring formulations to target, action, context and time, were not applicable to a wide variety of behaviors, or were ambiguous, seven prototypical items remained. These items lend themselves well for further psychometric study to establish the conceptual independence of self-identity from other Reasoned Action Approach constructs such as attitude and perceived norms.