Hemisphere asymmetries is about the lack of equality in the two hemispheres in the brain, i.e. the right and left hemisphere do not have the same cognitive and behavioural functions in the same way. It would be fair to put forward a suggestion that hemisphere is affected by both handedness and gender. Fossilised brains are interesting to look at but unfortunately cannot tell us how brain functioning occurred million and millions of years ago, if they did we could determine how the brain may have developed over time. However we do know more about how brain functioning occurs today thanks to research by Broca (1861) , Wernicke (1871) and Roger Sperry (1950's) leading the way. I will next have a look at Sperry and the split-brain studies.
Sperry devised a method to test split brain patients in the 1950's . Following treatment resistant epileptic patients inability to lead normal lives an operation was carried out to cut the corpus collasum, known as the commissurotomy or 'split brain' operation cutting the information 'bridge' between the right and left hemisphere. Sperry devised the divided field technique, which involved presenting words and pictures to split brain patients to the separate hemispheres. This provided some research to show that most of our language processing is in the left hemisphere but not all as the right hemisphere does recognise concrete nouns (names of objects) and that our visuo-spatial stimuli is processed in the right hemisphere.
Further studies by Bever and Chiarello (1974) suggests that the left hemisphere processes words and deals with sequential, information distributed over time breaking it down into separate components. When Bever and Chiarello tested musicians and non-musicians in a music recognition test, they found their left hemisphere superiority for musicians and right hemisphere superiority for non-musicians. This was because non-musicians will process music as a whole and musicians will break it down into different compartments looking at musical phrases cords and rhythms using the left hemisphere. Below, I will look at the possible affects of gender on the brain.