If you’re planning on telling a lie, try staying away from the loo for a while beforehand.

That's because a full bladder makes you a better fibber, researchers have found.

People who lied to an interviewer while needing to urinate were better at evading detection, the psychologists from California State University said.

The researchers said their findings provide support for the ‘inhibitory spillover effect’ – where the benefits derived from self-control in one task ‘spill over’ to control other tasks, if carried out at the same time.

That is, the act of physically controlling the bladder aids the simultaneous control of the complex thought processes that are involved in lying.

‘Lying requires a great deal of mental resources,’ said study author Iris Blandon-Gitlin.

‘Manipulation of information such as suppressing irrelevant thoughts - i.e. telling the truth - and providing a believable story while monitoring one’s and other’s behaviour, are among the tasks that the liar has to juggle.

‘Research has demonstrated that lying, much more than truth-telling, is a cognitive (mental) complex task that requires a great deal of inhibitory control.’

Having a full bladder might help someone lie better because it activates the inhibition control centres in the brain, she said.

To lie, our brains have to inhibit the urge to tell the truth. If our brains are already inhibiting the urge to urinate, it could make it easier for us to lie.

‘The control centres in the brain – the inhibitory network – are not domain-specific and activating the network with one self-control will activate other parts of the network, facilitating performance in another self-control task (completed simultaneously),’ she said.

‘This reveals the “inhibitory spillover effect”.’

For the study, participants were asked to drink either 700ml, or 50ml, of water 45 minutes before they had to lie to an interviewer about an issue they felt strongly about.

Those with a full bladder were better able to disguise that they were lying.

The researchers added that future studies could investigate the role of ISE in controlling depressive thinking, and preventing unhealthy behaviours.

The study was published in the journal Consciousness and Cognition.