June 4 (HealthDay News) -- As if folks needed another reason to be annoyed at other people's cell phones, researchers now report that just 30 seconds of a stranger's nearby ringtone can impair thinking, at least briefly.
Students unwittingly involved in a classroom experiment saw their test scores sink after a fellow "student's" phone went off.
The finding shows that "there are real-world implications for these sounds in our environment," said study lead author Jill Shelton. "They are distracting. They significantly disrupt performance in a classroom setting."
Shelton, who recently published the findings online in the Journal of Environmental Psychology, said, "this data says it's not just annoying. It's actually leading to impairment in learning, whether in a business meeting or in a classroom or some other setting." She is currently a post-doctoral fellow in the department of psychology at Washington University in St. Louis, but completed the study while a doctoral student at Louisiana State University.
The bulk of the research into the impact of cell phones has focused on their use while driving. Most of that research has found a distracting and potentially dangerous mix.
Prior research has also indicated that the human brain can only attend to a finite amount of stimuli at a time.
In the new study, Shelton and her co-authors conducted a series of experiments, both in the lab and in "real world" university settings, to see how cell phone rings affected cognitive performance.
First, in the lab, students were exposed to different types of sound: "irrelevant," non-cell-phone-related noise from an undetermined source; a standard cell phone ring; and a ringtone consisting of bars from the Louisiana State University fight song.
"At this time, LSU was running for their national championship in football," Shelton said. "Ninety-nine percent of people [in the study] knew what this song was."
Students were asked to perform a simple task on the computer -- making decisions on whether the symbols they saw on the screen were words or not words. They were not told there would be distractions, but there were. In fact, noises (including cell phone rings) interrupted the task about 20 times in each trial.
The result? "All participants who heard a sound were initially distracted, no matter what the sound was. And they performed much more slowly on their task," Shelton said.
However, those who heard the irrelevant noise were able to get back to their task much faster than people hearing either one of the two cell phone rings. And those hearing the LSU fight song ringtone took the longest time to shake off the mental distraction.
Why might distraction be worse for a cell phone ring than for more "irrelevant" noise?
"We think it's because cell phones are more prevalent in the everyday environment. People are used to responding to cell phones," Shelton postulated. "They have this automatic reaction to it that they can't control and this is particularly true if we're talking about a cell phone ringtone that is personally relevant to them."
In all cases, though, Shelton said, "while these sounds were indeed disruptive, they were brief and people could recover, at least in a lab setting."
But next, Shelton pretended to be a student in an undergraduate class on child psychology.
At a pre-designated time, Shelton's cell phone rang for about 30 seconds while she made no move to answer or silence it, prompting a number of displeased looks from her lecture-hall mates.
Immediately afterwards, students performed 25 percent worse on a pop quiz containing questions pertaining to the information that had been presented (both orally and visually) while the cell phone was ringing.
"This was a pretty big drop in performance," Shelton said.
In another experiment, Shelton rummaged mercilessly through her bag to find the phone. After this incident, students performed even worse on their recall.
When people were warned beforehand that the cell phone would ring, the break in attention was less severe, Shelton said.
"Giving people warning may help them to ignore it," Shelton said.
According to background information in the paper, more than 262 million people in the United States use cell phones. Shelton said that, right now, most universities seem to be relying on students' common courtesy to tame cell phone use during class, rather than explicit rules.
There's information on state laws on cell phones/driving at the Governors Highway Safety Association.
SOURCES: Jill T. Shelton, Ph.D., post-doctoral fellow, department of psychology, Washington University, St. Louis; online Journal of Environmental Psychology