Finally: Anti-fear injections

Lead researcher Professor Masayuki Yoshida said: ‘The goldfish soon became afraid of the flash of light because, whether or not we actually gave them a shock, they had quickly learned to expect one.

‘Fear was demonstrated by their heartbeats decreasing, in a similar way to how our heart rate increases when someone gives us a fright.’

However, the team discovered that fish which had been injected in the cerebellum with the anaesthetic lidocaine an hour before the experiment began had stable heart rates and showed no signs of fear when the light was shone.