Making 'Pavlov's Cockroach'

In an experiment that made him a household name, the Russian scientist Ivan Pavlov a century ago got dogs used to hearing a bell every time they were fed. The dogs soon started drooling whenever they heard the bell.

Britain faces drought after dry winter

Southeast England faces a summer of drought after the driest 15 months in 30 years, but northwest Scotland and Wales have had more rain than usual.