The questions were designed to test their recall.
Those who closed their eyes while trying to remember answered 23 per cent more of the questions correctly than those who did not.
Building rapport also increased the number of correct answers, but closing the eyes improved performance whether or not this was achieved.
Study leader Dr Robert Nash, of the University of Surrey, said: "Although closing your eyes to remember seems to work whether or not rapport has been built beforehand, our results show that building rapport makes witnesses more at ease with closing their eyes.
"That in itself is vital if we are to encourage witnesses to use this helpful technique during interviews."
For the second experiment, volunteers were shown a Crimewatch reconstruction of a burglary in which an elderly man was attacked in his home.
This time participants were asked to remember what they had heard as well as what they had seen.
Closing the eyes helped them recall both visual images and sounds.
The research is published in the journal Legal and Criminology Psychology.
- PAA