The study suggests that if the brain is focused on inhibiting the urge to urinate, it may be easier to lie Corbis

Being desperate for the lavatory could be the key to telling a convincing lie, according to a study that found an apparent link between full bladders and good fibbers.

Researchers at California State University asked volunteers to drink different volumes of water, ranging from five sips to five glasses, and waited 45 minutes before asking them to lie about a strongly held opinion in front of an interviewer and a camera.

Despite the urgent need to relieve themselves, those with full bladders were found to tell complex lies more comfortably and convincingly, with only 30 per cent of their lies being foiled.

It is far easier to tell the truth because all the brain has to do is think, whereas lying involves the complex process…