PORTLAND, Maine — Cellphones make it more difficult for humans to perform complicated tasks, even when they’re not being actively used, a new study from the University of Southern Maine found.

“It’s kind of disturbing,” said USM psychology professor Bill Thornton, who led the study. “There’s lots of research about the distracting use of a cellphone, when you’re driving or walking, at work or learning. That might seem intuitive or obvious. But here, just the fact that the mere presence of the cellphone has a negative impact is interesting.”

With Thanksgiving coming up, Thornton said it’s probably not enough to ask family members not to answer their phones at the table. Everybody should probably leave their phones elsewhere entirely, at least as far away as another room, he said.

A paper about the findings by Thornton and three of his students — Alyson Faires, Maija Robbins and Eric Rollins — is due to appear in an upcoming edition of the journal Social Psychology.

“Cellphones are just so present,” Thornton told the Bangor Daily News this week. “They provide you with this constant connectivity, so much that you become preoccupied with it. It’s the first thing you do in the morning and the last thing you do at night. Somewhere I saw it reported that 12 percent of people answer their cellphones or texts even when they’re having sex. These are symptoms that are consistent with behavioral addictions.”

For their study, Thornton and his students worked with four people at a time, paired up randomly in groups of two. Both pairs were given the same cognitive tasks to accomplish. The researchers placed a notebook on the table next to one of the pairs, and a cellphone next to the other pair.

The cellphone belonged to one of the researchers, so there was no expectation by the participants that they would be receiving calls or texts on it.

“On the simple tasks, there wasn’t any influence by the presence of the cellphone,” Thornton said. “But when the tasks became more complex, the presence of the cellphone began to have an impact on their performance.”

The USM study built upon similar research done previously by Netta Weinstein and Andrew Przybylski of the University of Essex in the United Kingdom, which showed people to be less trustful and have less favorable opinions of other people in face-to-face interactions when cellphones were present.

The Maine researchers have added to the list of the devices’ potential harm.

Thornton said his team asked study participants to do two exercises, one called a digit cancellation exercise and one called a trailmaking exercise.

In the digit cancellation puzzle, people first are asked to find and cross out certain numbers in an array of number rows. Then, when researchers are ready to ratchet up the complication factor, participants are asked to find and cross off every set of adjacent numbers that add up to equal the target numbers, such as 3 and 4 or 5 and 2 if the target number is 7.

In the trailmaking task, people are asked to draw a line from one number to the next in sequential order — from 1 to 2 to 3 and so on. The more complicated version of the test requires participants to alternate between numbers and letters, so to draw the line from 1 to A to 2 to B to 3 to C and so on.

In the simple versions of the tests, the participants all performed about equally. But when the more difficult version of the trailmaking exercise was performed, the participants with notebooks made an average 15.5 correct connections, while those with the cellphones averaged 12.5 correct connections.

In the more complicated version of the digit cancellation exercise, participants with the notebook got an average of 23 correct, while those with the cellphone got 20 correct.

“Three cancellations is not a huge number, but it’s a statistically significant difference,” Thornton said. “Not likely to have happened by chance.”

Thornton and his team tested 54 participants from the public and another 47 who were students in his classes. He said the tests performed by participants are commonly used to determine humans’ cognitive abilities or concentration levels.

The tests can be compared to other everyday tasks which challenge the brain on multiple levels, according to Thornton.

“If you’re the only one on the road, and the road is dead straight, you can probably hold the cellphone up at the wheel and text and probably be OK, because it’s a very simple task,” Thornton said. “But as soon as there is traffic, people are changing lanes and it’s a curving road, if you’re trying to text, it’s going to definitely negatively impact your driving. … Instead of outlawing its use, it may make sense to outlaw its presence.”

Even in less dangerous situations, he said, cellphones should perhaps be informally outlawed. Like at the Thanksgiving table.

“Here’s the time when the family gets back together again, it’s the biggest travel time of the year and everyone has spent a lot of money and gone great distances to be with each other,” he said. “And from this perspective, you all have your cellphones and you’re thinking about who you’re not with instead.”

Seth Koenig

Seth has nearly a decade of professional journalism experience and writes about the greater Portland region.