The aim of this experiment was to investigate the effects of hemisphere deconnection and to show that each hemisphere has different functions.
The participants were 11 ‘split-brain’ patients, that is, they were patients who had undergone disconnection of the cerebral hemispheres. The participants had all undergone hemisphere deconnection because they had a history of advanced epilepsy which could not be controlled by medication.
Sperry used a number of ingenious tasks in order to investigate lateralisation of brain function.
One of the tasks used to send information to just one hemisphere involved asking participants to respond to visual information. This involved blindfolding one of the participant’s eyes and then asking them to fixate with the seeing eye on a point in the middle of a screen. The researchers would then project a stimulus on either the left or right hand side of the fixation point for less than 1/10 of a second. The presentation time is so small to ensure that the participant does not have time for eye movement as this would ‘spread’ the information across both sides of the visual field and therefore across both sides of the brain.
As language is processed in the left hemisphere, when a stimulus is presented to the left visual field of a split-brain patient they should not be able to name the stimulus.
Below is a summary of some of the main results
When participants were presented with an image in one half of their visual field and then presented with the same image in the other half of the visual field they responded as if they had never seen the image before. If the same image was presented in the original visual field the participants were able to recognise the image as one…