Just like Pinocchio, our noses appear to signal when we're lying.

But instead of growing longer, they heat up when we're fibbing, according to Spanish research.

Psychology researchers at the University of Granada used thermo imaging to measure the temperature of people's faces and found it spiked around the nose and the orbital muscle in the inner corner of the eye when they told lies.

But when people experienced high anxiety or were doing a difficult mental task, their face temperature dropped.

The researchers, Emilio Gomez Milan and Elvira Salazar Lopez, are exploring the link between temperature and psychology in many different settings and believe the temperature change is due to increased activity in the brain region called insula.

When they used thermography to measure sexual excitement and desire, they found it increased the temperature in the chest and genitals.

They also discovered highly empathetic people who watched a person getting an electric shock to their forearm also experienced an increase in forearm temperature.

Their research is part of their doctoral thesis and is yet to be published in a scientific journal.