Glimpses of junk food are potent magnets for attention, Hopkins study finds

The end-of-year holidays can mean plenty of extra work given all the shopping, party planning and meal preparing involved.

If two Johns Hopkins University research psychologists are to be believed, another hallmark of this time of year — the easy availability of junk-food including Halloween candy, Thanksgiving pies, Christmas cookies, and New Year’s Eve desserts — makes the labor all that more difficult.

A recent study by Corbin Cunningham and Howard Egeth, a doctoral student and a professor in the university’s department of psychological and brain sciences, found that when individuals engaged in a task are shown pictures of “calorie-dense” foods, they become significantly — and measurably — more distracted than they are when shown other kinds of pictures.

Color pictures of a piece of candy, a piece of pie or a slice of pizza, for example, proved twice as distracting for these randomly chosen participants than did images of healthier, lower-calorie foods such as tomatoes, celery and salads. The junk-food images also were twice as distracting as photos of ordinary, non-perishable items such as lamps, footballs, ball-point pens.

The findings are published in an article — “The Capture of Attention By Entirely Irrelevant Pictures of Calorie-dense Foods” — in the most recent edition of the journal Psychonomic Bulletin and Review.

They reaffirm an idea borne out by multiple behavioral-science studies in recent years — that food draws the attention of human beings across cultures with amazing speed and at a deep psychological level — but introduce one more layer to the discussion, suggesting that the exact kinds of foods our mothers, grandmothers and doctors warned us against grab attention even more effectively.

It’s too soon to know what the results suggest about the desires, needs and psychological makeup of humans — Do they have an innate or learned bias toward sugary, fatty foods? If so, what’s behind it? — but the researchers say the findings put behavioral scientists in a better position to investigate.

“This raises a whole series of very interesting questions, doesn’t it?” Egeth said.

The researchers also found that if participants consumed two fun-sized candy bars before taking part in the experiment, they became no more interested in the junk food than they were in kale or cauliflower or the non-food images — underscoring, perhaps, that physical desire has an effect on what attracts our minds.

Studying attention is nothing new for Egeth, who first became interested in the subject as a boy in New Jersey.

An avid reader, he was often a source of frustration for his parents, who found that when he was engrossed in a book they had to work extra hard — and speak extra loudly — to get his attention.

He found himself wondering what affects and defines what we focus on — whether it’s a conscious or unconscious process, how it works and how quickly — and followed his interest from the field of physics into academic psychology, where he has studied attention for 50 years.

Cunningham, a predoctoral fellow in the Science of Learning Institute at Johns Hopkins, began his academic career as a photographer who was curious about how the mind processes color.

His interests led him to Harvard, where he took part in psychological studies aimed at helping “search professionals” — radiologists scrutinizing X-rays, for example, or airport screeners seeking contraband — find what they’re looking for more quickly and efficiently.

In a study he led with Egeth in 2015, he discovered a variation on the so-called White Bear phenomenon.

The term originated with the novelist Fyodor Dostoevsky, who once observed that the surest way to end up thinking of a polar bear is to resolve not to think of one — a phenomenon psychologists call thought suppression.

They showed that while thought suppression initially has the opposite of the intended effect, people can use it to their advantage over time. If TSA agents remind themselves not to dwell on items they know are legal, for example, and work at it, they can find the illegal ones more quickly.

“You can get good at this, if you practice,” Cunningham said.

The junk food project teased out similar subtleties. Conducted over a period of weeks last year, the study asked dozens of volunteer subjects — all of them Hopkins undergraduates — to take a computer test that asked them to look at four characters per computer screen and decide, as quickly as possible, whether each was a number or a letter. As they did so, researchers periodically flashed an image unrelated to the task — a broccoli spear, a candy bar, a light bulb — at one edge of the screen.

In order to reduce variables, the researchers used pictures from a Dutch database in which every photo had similar color saturation and density, regardless of subject. The images flashed by in 125 milliseconds each — less than a tenth of a second, too quickly for the mind to recognize and consciously process — but each slowed the participants down.

The images of low-calorie foods and of the random objects added an average of about 12 milliseconds to their task completion. Those of the high-calorie and high-fat foods — the sugary snacks, the pizza, the processed meats — added 24 milliseconds on average.

“They’re small effects, but the difference between the categories was consistent and significant,” Egeth said.

Cunningham said it’s important to keep in mind that not all the more distracting foods fit the category of “junk food” as most Americans define it.

Steaks, hamburgers, hot dogs and cheeses drew as much attention as milk shakes and candy canes.

“I try to use the term calorie-dense,” he said.

Most of the tasty foods Americans associate with the holiday season fit the classification, though, whether it’s licorice and candy bars served on Halloween, pumpkin pie and dressing on Thanksgiving, doughnuts and potato latkes during Hanukkah or candy canes at Christmas.

As the season’s stresses mount and people’s to-do lists grow longer, the scientists say, it might be a good idea to show restraint in the consumption of treats, at least for those who are trying to get seasonal tasks completed

And whatever their implications, Egeth said the findings bear echoes of culinary wisdom as familiar to many as pumpkins on Halloween or turkey at Thanksgiving.

“Follow-up studies are needed, and we’re already doing some of those,” Egeth said. “In the meantime, we’re learning that what our grandmothers told us is probably true: it does spoil your appetite to eat before dinner — and it’s never a good idea to go shopping when you’re hungry.”

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