Altercast framing with assertive sustainability messages: how dominant brands can motivate non-green consumers

Advertisers often use assertive messages because they minimize ambiguity, are attention-grabbing, and encourage behavioural compliance, making them a popular message design strategy in sustainability advertising. However, assertive messages often backfire for 'non-green' or lower environmental concern (LEC) consumers, generating more negative attitudes toward the ad sponsor and entrenching existing behaviours. Advertisers employ subtle phrasing to mitigate this adverse effect, reducing the message's assertiveness. While research has investigated different variations of subtler message designs, no research has yet to explore how to maintain an assertive message toward achieving more favourable source attitudes and greater behavioural compliance intentions. The current research draws on message framing and altercasting theory to create a new concept – altercast framing – that preserves the core assertive message. Three experimental studies reveal that altercast framing can enhance brand attitudes and behavioural intentions for LEC consumers but only when the message source is a high (versus low) market share brand. This research contributes to advertising theory and practice by (a) developing a novel message framing concept that preserves the core message, (b) expanding on message assertiveness research by integrating both message sender and message receiver characteristics toward maximizing ad effectiveness, (c) identifying the differential effect of a specific message sender characteristic – market share – on assertive messages, and (d) outlining an advertising strategy that enhances behavioural compliance intentions for LEC consumers.