Assessing the effectiveness of prosocial activism within sponsored influencer posts on product promotion

Mandatory sponsorship disclosure has reduced the value of influencer campaigns, as consumers are astutely aware of their promotional nature. At the same time, influencers are mobilising as activists for prosocial causes. Against this backdrop, we ask: Do activism statements within sponsored influencer posts increase their effectiveness? and if so ‘why’ and ‘when’? Through one behavioural pilot study and four experiments, we reveal that activism statements in sponsored influencer posts prompt consumers to spend more time browsing the promoted product website and increase their purchase intentions. These effects are explained by a reduction in the activation of persuasion knowledge (i.e. reduced perceived selling intent). We further show that the positive effect of combining activism with product promotion is attenuated by the consumer’s high level of cynicism. Moreover, influencer-cause congruence boosts the positive effects of sponsored activism posts; however, incongruence causes these posts to backfire by raising perceived manipulative and selling intent. By intersecting two common phenomena in influencer posts (sponsorship disclosure and prosocial activism), we extend knowledge on the antecedents of sponsored influencer posts' success and offer strategies for marketers to harness them.