Explaining the effect of event valence on unrealistic optimism

Area of Science:

• Psychology
• Social Psychology
• Cognitive Bias

Background:

• Unrealistic optimism (UO) is the tendency to overestimate positive and underestimate negative personal life events compared to others.
• The 'valence effect' describes UO being stronger for negative than positive events, often attributed to motivational factors.
• The 'numerosity model' offers an alternative explanation, suggesting the valence effect arises from how group size influences likelihood estimates.

Purpose of the Study:

• To test the predictions of the numerosity model against motivational explanations for the valence effect in unrealistic optimism.
• To investigate whether group size influences unrealistic optimism and the valence effect.
• To determine the primary drivers of the valence effect in personal likelihood estimates.

Main Methods:

• Two studies were conducted with university students (N=115 and N=139).
• Participants estimated their own likelihood of experiencing events and the likelihood for the average person.
• Event valence (positive/negative framing) and, in Study 2, group size were manipulated.

Main Results:

• The valence effect was observed in both studies, manifesting as a stronger bias for negative events.
• This effect was primarily driven by changes in participants' estimates of their *own* likelihood, not their estimates of the *average person's* likelihood.
• In Study 2, group size did not significantly interact with or explain the valence effect.

Conclusions:

• The findings contradict the numerosity model's predictions regarding group size influence.
• Results support motivational explanations for the valence effect in unrealistic optimism.
• The study highlights the importance of personal perception biases in unrealistic optimism, with implications for health education strategies.