In a study by David Asch in 1994, it was found that many parents avoided vaccines because they believed the possible side effects of the vaccine were worse than the risk of their child getting the disease. Essentially, they felt that doing nothing (not vaccinating) was safer than taking action (vaccinating), even though the opposite is true.

In an experiment, participants were presented with the following scenario: John is a talented tennis player, though not skilled enough to go professional. Every year, his tennis club hosts a tournament with a substantial prize, attracting professional players. John reaches the finals, where he is set to compete against a famous professional player. The night before the game, all players dine at a salad bar. John knows that the pro player is allergic to cayenne pepper, which is an ingredient in the house dressing. Participants were then asked to evaluate John's morality in three different actions: John recommends the house dressing to the pro player. John does nothing when the pro player orders the house dressing. John suggests switching to the house dressing after the pro player initially chooses the Italian dressing. The results revealed that 65% of participants found option B (doing nothing) to be less immoral than the other options. This finding illustrates omission bias, where inaction is perceived as more morally acceptable than harmful actions, even when the outcomes are equally detrimental.