*4.3. Theoretical Approaches Explaining the Impact of Green Marketing on Customer Behavior*

This section summarizes different theoretical approaches toward desirable customer behavior with green marketing. We investigate theoretical reasoning in customer behavior theories concerning approaches to green marketing, enabling us to determine the biases and possible development directions of green marketing research.

Of the 166 documents, 66 (39.76%) provided a theory or model explaining customer behavior and green marketing as its antecedent. The remainder of the articles discussed green marketing's impact on customer behavior without explicitly choosing the theory or model (Table 3).

The theory of planned behavior is the most famous theoretical perspective on customer behavior in green marketing. This perspective considers attitudes, subjective norms, and perceived behavioral control as predictors of customer behavior. Although the recent marketing literature [69,70] criticizes the theory of planned behavior, this framework has profoundly influenced the evolution of customer behavior literature. Green marketing tools through the lens of the theory of planned behavior were introduced in the study by Testa et al. [45]. The authors focused on the effectiveness of one particular green marketing tool, eco-labeling. Since then, the popularity of the theory of planned behavior has been gradually increasing. For example, in a recent research, Ch et al. [8] emphasized that the theory of planned behavior strongly supports green purchasing behavior.

The other theoretical perspective, the theory of reasoned action, was also widely employed for research into adjusting customer behavior through the tools of green marketing. We have accumulated evidence of the use of this theoretical foundation in the studies of the impact of eco-labeling [45], green appeal [47], perception of green products [49], etc. The

repeated applications of the theory of reasoned action are related to the aforementioned theory of planned behavior, as the theory of reasoned action originated as an improved version of the theory of planned behavior.

The other scholars have chosen stimulus-organism-response, cognition-affect-behavior, environmentally conscious customer behavior, four forces models, attitude-behaviorcontext, attribution, regulatory focus, or value-belief-norm theories as conceptual frameworks. Most research was based on one theory, but some scholars combined two or more theoretical perspectives. For example, Liao [56] confirmed that the combination of signaling and attitude-behavior-context theories could explain the moderation of green marketing on customers' purchase intention. However, some authors [2,68,69] did not exploit any theories.
