Toward an ontology of identity-related constructs in addiction, with examples from nicotine and tobacco research.

Background And Aims: We aimed to create a basic set of definitions and relationships for identity-related constructs, as part of the Addiction Ontology and E-Cigarette Ontology projects, that could be used by researchers with diverse theoretical positions and so facilitate evidence synthesis and interoperability.

Methods: We reviewed the use of identity-related constructs in psychological and social sciences and how these have been applied to addiction with a focus on nicotine and tobacco research. We, then, used an iterative process of adaptation and review to arrive at a basic set of identity-related classes with labels, definitions and relationships that could provide a common framework for research.

Results: We propose that 'identity' be used to refer to 'a cognitive representation by a person or group of themselves', with 'self-identity' referring to an individual's identity and 'group identity' referring to an identity held by a social group. Identities can then be classified at any level of granularity based on the content of the representations (e.g. 'tobacco smoker identity', 'cigarette smoker identity' and 'vaper identity'). We propose distinguishing identity from 'self-appraisal' to capture the distinction between the representation of oneself (e.g. as an 'ex-smoker') and (i) the importance and (ii) the positive or negative evaluation that we attach to what is represented. We label an identity that is appraised as enduring as a 'core identity', related to 'strong identity' because of the appraisal as important. Identities that are appraised positively or negatively involve 'positive self-appraisal' and 'negative self-appraisal' respectively. This allows us to create 'logically defined classes' of identity by combining them (e.g. 'positive core cigarette smoker identity' to refer to a cigarette smoker self-identity that is both positive and important). We refer to the totality of self-identities of a person as a 'composite self-identity'.

Conclusions: An ontology of identity constructs may assist in improving clarity when discussing theories and evidence relating to this construct in addiction research.