Can scientific methods be used to study the mind? We are all familiar with the idea the scientists study all the nooks and crannies of the natural world - from tiny cells to collosal constellations But can the same tools be used to study unobservable thoughts?

For a long time this idea would have been ridiculous. Philosophers like Descartes argued the mind was completely separate from the material world, and many thinkers saw automata (like this guy) as a sign that observable action could be explained without reference to a 'mind'

The scientific status of the mind was also damaged by psychoanalysis. While Freud & disciples brought into focus the idea we may not be conscious of our own mental processes, their methods were critiqued for providing 'just-so' stories about behaviour lacking scientific rigour

Perhaps because the reputation of the mind was tainted, early experimental psychologists were 'behaviourists'. They didn't deny that thoughts or feelings *existed*, but were steadfast in arguing the only thing scientists could usefully theorise about was observable behaviour.

The behaviourists wanted to uncover the laws that governed the relationship between observable events and observable actions. This often meant seeing how the behaviour of animals like rats could be sculpted by schedules of reward and punishment.

The behaviourists generated lots of data about how simple creatures could be 'conditioned' by pleasant (e.g., food) and aversive stimuli (e.g., electric shocks), but their project hit several stumbling blocks.

Even humble animals show behaviour that doesn't depend on reinforcement. Tolman found that rats could learn the layout a maze without any incentives - and were faster to find food when it was later added. How can we explain this 'latent learning' without talking about memories?

Behaviourists also struggled to explain some more sophisticated human abilities. In 1959, Noam Chomsky challenged the prominent behaviourist BF Skinner to explain how children learn to speak a language - given the appropriate schedule of rewards & punishments don't exist.

So it looked like scientific explanations of behaviour - in humans and other animals - were going to have to start theorising about what was going on inside their heads. But what's the best way to start?