It’s often hard to keep information straight, even when it affects your health. A memorable example of this came from a Canadian study a few years ago, which asked people to read through a series of health claims (such as “X helps prevent cancer”), all labeled as either true or false. Many people remembered true statements as being false and, more often, false ones as being true. That shows how wires can get crossed in the memory switchboard.
That research came to mind when we recently read an Israeli study in the journal Psychological Science, which looked at the effects of warning labels, seen on a variety of products. In four experiments, the researchers found that, rather than making consumers think twice about such products, warning labels can make the products seem more appealing—provided there is a time lag between reading the warning and then deciding whether or not to buy the products.
In one experiment, for instance, women (average age 35) were shown ads for a new artificial sweetener, either with or without a warning about potential adverse effects. When they were given the chance to buy the sweetener right away, the warning greatly depressed sales, presumably because of increased safety concerns. But when women shown the warning were given the chance to order the sweetener two weeks later, they were more than twice as likely to buy it as women not shown the warning. Similar results were seen in three other experiments.
This suggests that when there was a lag time, the warnings may actually have encouraged trust and led to more positive product evaluation and thus more purchases. Consumers may have initially felt they were given all relevant information about the products, but then forgot the negative details. This is called the “sleeper effect,” which causes a message’s negative impact to fade over time. Even more disturbing, “informing people of the risks associated with a medical procedure or an investment option, for example, may ironically increase the likelihood that they will adopt the risky behavior,” the researchers concluded.
Words to the wise: You may have wondered why drug companies are willing to run TV ads at the end of which they’re required to run long lists of scary side effects. They probably know that memory will play tricks on viewers. Now you’ve been warned.