Laptops have replaced pen and paper for many post-secondary students but a Canadian study suggests using computers during lectures could be hurting their grades and lowering their classmates' marks.

For the study, published earlier this year in the journal Computers & Education, research subjects in two experiments were asked to attend a university-level lecture and then complete a multiple-choice quiz based on what they learned.

In the first experiment, which was designed to gauge how multitasking affects learning, all the participants used laptops to take notes during a lecture on meteorology. But half were also asked to complete a series of unrelated tasks on their computers when they felt they could spare some time. Those tasks — which included online searches for information — were meant to mimic what distracted students might do during class.

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In the second experiment, some students were given pencils and paper to take notes during a lecture while others worked on laptops. Researchers wanted to observe if the students taking notes the old-fashioned way would be distracted by having computer screens around them.

Faria Sana, who co-authored the study with fellow doctoral student Tina Weston, said she expected lower test marks for students who were asked to multitask during the experiment, or were seated near other students using laptops. But the distraction effect was stronger than she hypothesized.

"We really tried to make it pretty close to what actually happens in the lectures, we found that lo and behold, the students who multitasked performed much worse on the final test and those who were seated around peers who were multitasking also performed much worse on the final test," said Sana.

"So you might not be multitasking but if you have a clear view of someone else who is multitasking, your performance is still going to be impaired."

The students in the first experiment who were asked to multitask averaged 11 per cent lower on their quiz. The students in the second experiment who were surrounded by laptops scored 17 per cent lower.

"We really didn't think the effects would be this huge," Sana said. "It can change your grade from a B+ to a B-."

Sana also noted that the students who participated in the experiments said they didn't really expect their marks to suffer much from computer use in the classroom.

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"At the end we gave a survey to all the students and what we found was that these peers who were seated around multitaskers had no idea they were being distracted, they didn't think the laptops were causing a distraction but based on the scores of their final test, they actually were," she said.

Seeing dozens of laptops in a classroom is now common, Sana said, as is spying some students on social networks, playing games or watching movies instead of paying attention.

While Sana and Weston are not calling for a ban on laptop use in classes, they do hope students consider that goofing off on their computers can affect their peers seating around them.

"A lot of students spend quite a big chunk of time in class doing things that are not related to the academic environment or aren't directly related to the course or the lecture," Sana said.

"We're hoping that based on these results, students will take responsibility for their actions."