The researchers from Chinese University of Hong Kong and Stanford University believe that a person’s "shaken self" persists until he or she is able to do, acquire, or think about something that restores the self-confidence.

"We show that threats to an important self-view can momentarily shake one’s confidence in that particular self-view, resulting in the choice of products that help restore confidence in that self-view," wrote the authors.

During the study, the researchers asked participants to write about health-conscious behaviours with their dominant or non-dominant hands.

Then some of the participants wrote essays about the most important value in their lives (an activity designed to restore confidence).

All participants assessed their moods and self-esteem levels and then chose between a healthy snack (an apple) and an unhealthy snack (candy bar).

The researchers found that participants whose confidence was shaken (by not using their dominant hand) who didn’t get to self-affirm with the essay were more likely to choose the healthy snack—to restore their health-conscious confidence.

The authors focused their research on the "shaken confidence" phenomenon in people who were generally self-confident.

"Specifically, we show that the effects of lowered self-view confidence on consumer choice can be eliminated by both direct self-view bolstering strategies (for example, purchasing products to restore the specific shaken self-dimension) as well as indirect strategies (for example, affirming an unrelated self-value)," the authors added.