We may be able to tell someone's heart rate just by looking at them

We may be able to tell someone’s heart rate at a glance, which could help us interpret their emotional state.

Alejandro Galvez-Pol at University College London and his colleagues showed 120 volunteers videos of two people positioned side-by-side. The heart rate of one of the individuals was shown on the screen, in the form of a square that changed colour from black to red with every heartbeat.

The participants were then asked to say who they thought the heartbeat belonged to. On average, they guessed correctly 58 per cent of the…