How Can Implicit and Explicit Attitudes Both Be Changed? Testing Two Interventions to Promote Consumption of Green Vegetables

Background: Although correlational studies have demonstrated that implicit and explicit attitudes are both important in predicting eating behavior, few studies targeting food choice have attempted to change both types of attitudes. Purpose: We tested the impact of (a) an evaluative learning intervention that uses the self to change attitudes (i.e., a Self-Referencing task) and (b) a persuasive communication in modifying implicit and explicit attitudes towards green vegetables and promoting readiness to change. The study targeted individuals who explicitly reported they did not like or only moderately liked green vegetables. Methods: Participants (N = 273) were randomly allocated to a 2 (self-referencing: present vs. absent) × 2 (persuasive message: present vs. absent) factorial design. The outcomes were implicit and explicit attitudes as well as readiness to increase consumption of green vegetables. Results: Implicit attitudes increased after repeatedly pairing green vegetable stimuli with the self in the self-referencing task but did not change in response to the persuasive communication. The persuasive message increased explicit attitudes and readiness to change, but did not alter implicit attitudes. A three-way interaction with pre-existing explicit attitudes was also observed. In the absence of a persuasive message, the self-referencing task increased on readiness to change among participants with more negative pre-existing explicit attitudes. Conclusions: This study is the first to demonstrate that a self-referencing task is effective in changing both implicit attitudes and readiness to change eating behavior. Findings indicate that distinct intervention strategies are needed to change implicit and explicit attitudes towards green vegetables.