Does Zero Mean Nothing? Investigating the Attentional Mechanism of the Hidden-Zero Effect in Risky Decision-Making

The framing of risky choices can shape and alter individuals’ risk preferences. Within every option in a risky choice (e.g., 70% chance to win $100), there is a naturally embedded but hidden zero outcome (e.g., 30% chance to win $0). Here, we tested the hidden-zero effect by comparing participants’ risky choices between two different conditions (i.e., presenting options with or without explicit-zero outcomes) with a full range of risky probability (5%–95%). The results showed that presenting zero outcomes explicitly led to more risky choices (Studies 1 and 2). Moreover, with eye-movement measurement and computational modeling, we then developed a series of models based on the Expected Utility and the Prospect Theory models to quantify the attentional process underlying this hidden-zero effect. These results further demonstrated that this effect is primarily driven by a choice bias toward the risky option. In Study 2, we found that this bias was mediated by increased visual attention to the risky option. These findings suggest that the utility of zero does not simply equal zero; rather, presenting the often omitted zero components may shift individuals’ attention toward risky options, encouraging them to take more risks.Keywords: attentional bias; hidden-zero effect; eye-tracking; computational modeling