A recent research has found that doing two visual tasks simultaneously affects performance and in that respect it is highly dangerous to text while driving.
Alarmingly, though, people who tried to do two visual tasks at the same time rated their performance as better than did those who combined a visual and an audio task - even though their actual performance was worse.
"Many people have this overconfidence in how well they can multitask, and our study shows that this particularly is the case when they combine two visual tasks," said Zheng Wang, lead author of the study and assistant professor of communication at Ohio State University.
Eye-tracking technology used in the study showed that people's gaze moved around much more when they had two visual tasks compared to a visual and an audio task, and they spent much less time fixated on any one task. That suggests distracted visual attention, Wang said.
People in the study who had two visual tasks had to complete a pattern-matching puzzle on a computer screen while giving walking directions to another person using instant messaging (IM) software.
Those who combined a visual and an audio task tried to complete the same pattern-matching task on the screen while giving voice directions using audio chat.
The two multitasking scenarios used in this study can be compared to those drivers may face, Wang said.
People who try to text while they are driving are combining two mostly visual tasks, she said. People who talk on a phone while driving are combining a visual and an audio task.
"They're both dangerous, but as both our behavioural performance data and eyetracking data suggest, texting is more dangerous to do while driving than talking on a phone, which is not a surprise," Wang said.
"But what is surprising is that our results also suggest that people may perceive that texting is not more dangerous - they may think they can do a good job at two visual tasks at one time," Wang noted.
These results suggest we need to teach media and multitasking literacy to young people before they start driving, Wang said.
In addition, the findings show that technology companies need to be aware of how people respond to multitasking when they are designing products.
For example, these results suggest GPS voice guidance should be preferred over image guidance because people are more effective when they combine visual with aural tasks compared to two visual tasks.
"We need to design media environments that emphasize processing efficiency and activity safety. We can take advantage of the fact that we do better when we can use visual and audio components rather than two visual components," Wang added.
The study appeared in a recent issue of the journal Computers in Human Behavior.