This study examined the effect of a misinformation awareness video on truth bias. Truth bias is defined as the tendency to believe information is true regardless of its actual accuracy. Additionally, the potential moderating roles of education level and age in this relationship were investigated. A total of 795 participants completed an online task in which they listened to a fictional crime report and evaluated the truthfulness of spoken statements about the crime. Prior to the task, participants were informed that one of the two speakers consistently told the truth, while the other provided false information. After listening to the report, participants had to indicate whether each statement was true or false. Truth bias was operationalized in this study by comparing the difference between the proportion of false statements incorrectly answered as ‘true’ and the proportion of true statements incorrectly answered as ‘false’. The intervention group watched a misinformation awareness video before the task to increase their understanding of truth bias. However, a repeated measures ANOVA revealed no significant effect of this intervention on truth bias. Additionally, age and education level showed no significant direct effects on truth bias, nor did they significantly moderate the effect of the intervention on truth bias. The findings support the Truth Default Theory, suggesting that people tend to believe others, even when warned about the possible presence of misinformation. The non-significant findings may indicate that a video intervention by itself is too insufficient to activate reflective thinking required to reduce truth bias, and that the effects of education level and age may be more context-dependent than previously thought.