Incidental anger and happiness increase intentional self-serving deception: An online study based on an ecological deception task

Deceptive, dishonest behaviour is a common occurrence in daily life. While several psychology and neuroscience studies have explored the factors that influence dishonesty, research on how incidental emotions affect moral decision-making remains limited. Influential models linking emotion and ethics, suggest that inducing specific emotions may bias individuals to become self-focused, and thus elicit self-serving deception, or other-focused and thus lead to truth-telling or prosocial lies. To expand on the knowledge inspired by these models, here we investigated how incidental anger, gratitude, and happiness influence dishonest behaviour. Using an ecologically-valid deception task, the Temptation to Lie Card Game, we found that egoistic lies were associated more to incidental anger and happiness than to gratitude. Moreover, levels of personality traits relevant for deceptive behaviours significantly correlated with a higher rate of egoistic lies for anger and happiness, but not gratitude induction. These findings align with recent models suggesting that the impact of emotions on moral decision-making is influenced by cognitive appraisal mechanisms, which affect how people evaluate future events, prioritizing themselves or others. Our study represents the first to compare the effects of multiple incidental emotions on deception and may serve as a foundation for exploring the link between emotions and moral-decision making at behavioural and neural levels.