By Catherine A. Sanderson, Amherst College
Our mindsets define our perceptions. It affects not only our thoughts, feelings, and behavior, but also brings about physiological changes. People who adopt positive expectations have better health outcomes and those with negative expectations show a negative response. Nonetheless, the power of perception is evident physiologically, too.
Positive Attracts Positive
The reason that people with positive expectations have better and healthier outcomes is because they use adaptive coping mechanisms to manage stress—tackling problems head-on, seeking out social support, and following medical recommendations.
These proactive approaches to stress minimize its effects and reduce wear-and-tear on the body. This means that their body is better able to fight off minor infections, recover from surgery, and so on.
Another explanation is that the mere act of believing itself changes your body’s physiological response. Remember, even placebos—which create a belief about treatment, without other intervention—can lead to changes in the body and brain, including the release of endorphins that inhibit pain.
Physiological Reaction to Food and Drink
Researchers in one study asked people to taste two apparently different French vanilla milk shakes, in a powerful demonstration of how perceptions influence the body’s physiological reaction to food and drink.
Some people were told that their shake was a diet drink called Sensi-Shake that contained no fat and no added sugar and was only 140 calories. Others were given the exact same drink but instead told that it was a rich dessert called Indulgence, high in fat and sugar and containing 620 calories. In reality, calories for both shakes were at the mid-point, at 380 calories.
After the participants finished the drink, researchers measured the level of a specific stomach hormone called ghrelin in their bodies. After we’ve eaten a big meal, our ghrelin levels drop, which tells the body, “You’ve had enough to eat”.
People who believed they had consumed the high-caloric drink showed a substantial drop in ghrelin levels, suggesting they were full, a change about three times greater than when they believed they had consumed the diet drink.
Simply believing they’d consumed more calories (when in reality they had not) led to changes in the body’s physiological response and a substantial drop in hunger.
This article comes directly from content in the video series Introduction to Psychology. Watch it now, on Wondrium.
Actual Physiological Changes
Although the precise mechanisms are not known, these findings profoundly illustrate the power of perception to lead to actual changes in the body. In fact, a 2018 study by researchers at Stanford University found that simply telling someone they have a genetic predisposition for obesity leads to physiological changes in the body, as does telling people they have a lower exercise capacity.
Some study participants ate a meal while others ran on a treadmill, depending on the specific study they were in. The researchers measured how their bodies responded to these tests.
Researchers took blood samples to assess levels of the ghrelin hormone measuring fullness for those who ate the meal; for those who ran on the treadmill, researchers measured lung capacity and how long they continued running. DNA samples were taken.
Misleading Perceptions
A week later, study participants returned and were given one of two genetic results, though in reality, results were randomly assigned, meaning results might or might not have been true for each person. Some people were given “good news” that they had genes that protected them from obesity or genes that gave them a higher exercise capacity. Others were given “bad news” that their genes predisposed them to obesity or their genes had a lower exercise capacity.
They were also given information that explained what these results meant. People eating were told that their bodies produced less of the hormone indicating fullness so they would tend to over-eat, or that their bodies produced more of the hormone. People exercising were either told that their bodies just weren’t able to exercise at as high a level as other people, or the reverse. After receiving their made-up results, the participants repeated the exact same test, eating a meal or running on a treadmill.
Influence of Misleading Perceptions
People who were told their genes protected them from obesity produced 2.5 times more of the hormone indicating fullness than they had the week before, so they actually did feel fuller significantly faster. Believing something positive made things better.
Those who were told their genes increased their risk of obesity saw no such change. People who were told their genes increased their exercise capacity performed at about the same level as they had the week before.
But those told their genes led them to have a lower exercise capacity performed significantly worse on the treadmill test. Their lung capacity was reduced and they quit running sooner. So, in this case, believing something negative made things worse.
As an aside, it must be noted that the researchers collecting this data on physiological response to the made-up results immediately afterward gave the study participants a debriefing, telling them the results were made-up and explaining the real purpose of the research.
Changing Mindset Makes All the Difference
Together, these two studies indicate that receiving genetic information can have a positive or a negative physiological effect on the body.
So, think about it; these findings tell us that receiving information about your risk for a particular disease—a pretty standard outcome from DNA testing—can itself actually influence that risk, for good or ill. These studies all point to what can be the single most important finding from the field of psychology: Simply shifting our mindset can make a big difference.
Common Questions about Power of Perception and Physiological Changes
The reason that people with positive expectations have better and healthier outcomes is because they use adaptive coping mechanisms to manage stress—tackling problems head-on, seeking out social support, and following medical recommendations.
Our mindsets define our perceptions and affect not just our thoughts, feelings, and behavior, but are also influential in bringing about physiological changes. People who adopt positive expectations have better health outcomes and those with negative expectations show a negative response.
The study indicates that receiving genetic information can have a positive or a negative physiological effect on the body. These findings tell us that receiving information about your risk for a particular disease—a pretty standard outcome from DNA testing—can itself actually influence that risk, for good or ill.
