The intervention is a three-step mini game named Hidden Picture Puzzle designed to induce the feeling of awe. In the game, participants will first see a picture of nature covered by six opaque blocks. They will be asked to guess the content of the picture. After making their choice, participants will be instructed to click the six blocks to gradually uncover the picture. Once all six blocks are removed, the full image will be revealed. In the final step, participants will be instructed to imagine themselves in the scene and describe their feelings by selecting the word from a provided list. To ensure that participants will have sufficient time to complete the imagination tasks, they will be required to pause for at least 15s before proceeding to indicate their immediate feeling. Each participant will complete four rounds of this mini game, each with a different picture.

For the control group, the mini game Hidden Picture Puzzle will also follow a three-step format, identical in structure to the intervention condition. However, the images provided will depict everyday objects (e.g., a sofa or a bottle) rather than nature scenes. Similarly, when participants are asked to guess the content of the picture. After the participants finish uncovering the pictures, they will be asked to imagine their interaction with these daily objects and describe the features of the objects by selecting a word from a provided list. As in the intervention group, participants in the control group will complete four rounds of the mini game, each with a different image.

The intervention is a three-step mini game named Hidden Picture Puzzle designed to induce the feeling of awe. In the game, participants will first see a picture of nature covered by six opaque blocks. They will be asked to guess the content of the picture. After making their choice, participants will be instructed to click the six blocks to gradually uncover the picture. Once all six blocks are removed, the full image will be revealed. In the final step, participants will be instructed to imagine themselves in the scene and describe their feelings by selecting the word from a provided list. To ensure that participants will have sufficient time to complete the imagination tasks, they will be required to pause for at least 15s before proceeding to indicate their immediate feeling. Each participant will complete four rounds of this mini game, each with a different picture.

Participants will be asked about their intentions to participate in future vaccination, mask wearing, and social distancing during next winter influenza season using a 7-point Likert scale (1=Never, 7=Certain).

Based on a hypothetical infectious disease pandemic, six vignettes will be shown to the participants, comprising three on vaccination and three on social distancing. Each vignette illustrates a trade-off between personal cost and social benefit in engaging in these prosocial behaviours. Participants will be asked to report how likely will they are to engage in the prosocial preventive behaviours using a 7-point Likert scale (1=Never, 7=Certain).

Participants will also be asked their intentions to engage in social activities using a 5-point Likert scale (1=Very unwilling, 5=Very willing).