Researchers investigated whether students produce poorer homework if they are watching a soap opera. They took 192 14-year-olds, divided them into three groups and gave them the same reading comprehension and memorisation exercises to perform.
The first group did the homework in front of a TV soap opera, while the second group simply listened to the programme's soundtrack. The third group were set to work with no distractions at all.
Pupils were given as much time as they required to complete their homework.
The researchers found that pupils who did their homework with the TV on took an average of 13 more minutes to complete their work than those working without distractions. The quality of the work they produced was poorer.
Writing in the September 2004 edition of the journal Educational Psychology, researchers Marina Pool, Cees Koolstra and Tom Van Der Voort said: "When homework is combined with watching television the student is charged with two tasks that compete for limited information processing resources.
"Combining homework and television may lead to an overload of information that exceeds attention capacity with the result that only part of the information can be processed."
The performance of pupils working with just the soundtrack was not significantly worse than that of those who had no distraction.
The researchers concluded from this that the major distraction during the work was looking up to watch the screen.
Ms Pool said: "Students did not use the television as a background radio, but very regularly shifted attention from their homework to the television screen - on average no less than 2.5 times per minute."
The researchers also found that watching a new episode of a soap opera was no more of a distraction than viewing a repeat.
Other influences that affect homework performance include the way teachers communicate assignments to their students and the attitude of their pupils.
Factors in pupils' home environment, including levels of parental interest, were also found to be significant.