Why do challenging tasks make consumers believe drugs wear off faster?

Imagine that you have a cup of coffee and sit down to read People magazine. How long do you think the energy boost will last before you reach for another cup? Would you need more caffeine if you tried to read War and Peace? A new study in the Journal of Consumer Research finds that consumers wrongly believe that pharmacological products such as coffee and aspirin lose their effectiveness when they engage in more strenuous activities.

"People make assumptions about how long it takes for products to wear off. For example, they know that cars burn gasoline more quickly when driving uphill than downhill and difficult workouts burn calories more quickly than easy workouts," write authors Veronika Ilyuk, Lauren Block (both Baruch College, City University of New York), and David Faro (London Business School).

However, when it comes to products like energy drinks and over-the-counter medications, consumers seem to be inappropriately generalizing about how long it takes for the effects of these products to wear off. Over five studies, the authors studied what they term the "rapid wear-off bias" as it relates to a person's perceived duration of a product's effectiveness.

In one study, participants were assigned a reading task and were asked to consume an energizing jellybean when they believed the effects of the previous one were wearing off. Some participants were given passages in a standard font (easy condition) and others were given passages in a light gray, italicized font, with shadowing in the middle of the page (difficult condition). Participants who read the dificult passage consumed jellybeans more frequently than those reading the easy passage.

Brands marketing pharmacological products can use these results to evaluate the intake instructions on their product packaging and help avoid accidental overdoses and other detrimental health-related outcomes. "Interestingly, we found that task difficulty does not affect a person's perception of how effective a product is in general. Rather, it uniquely affects judgments of consumption frequency," the authors conclude.