Sperry 1968 Flashcards
Aim
To investigate the effects of de connection and show that each hemisphere has a different function
Method used
Quasi experiment which used split brain patients and compared them with normal subjects in laboratory tests
Participants
11 split brain patients
What was the sample?
Opportunity sample
Why and when did the ppts have the commissarotomy
They had severe epilepsy which wasn’t responding to drugs
2 had it sometime before experiment but other 9 had it recently
Why did ppts have to remain silent
In case they passed information from the left side of the brain to the right side
Visual investigations - one visual field
Ppts had to cover one eye
They were asked to look at the fixation point on the screen
The image was shown for one tenth of a second
Why were the pictures only presented for one tenth of a second?
To prevent info going to the wrong half of the visual field
Visual investigations - both visual fields
Ppts had to look at the fixation point on the screen while two pictures were flashed at the same time either side of the fixation point
The screen sent the image of a key to the left side of the brain and the apple to the right side of the brain
They were asked to say what they had seen
They were asked to draw with their left hand what they had seen with their eyes closed
Tactile investigations - one hand
Ppts hands are hidden from their view
Ppts are asked to find an object matching to what they say on the screen
The object is placed in one hand without ppts being able to see what they are holding and they are asked to say what they have been given, and to point to what they have been given
Tactile investigations - both hands
Ppts works with their hands out of sight
Given two different objects in both their hands, they are taken away and the ppt is asked to find the objects by touch from a pile of items and then say what they have held
Tests in the right hemisphere
The left visual field is presented with an object on the screen. The ppt is asked to pick out similar objects by touch from a pile of objects
Simple maths problems are presented in the left visual field, the subject is asked to sort out objects by shape, size and texture
A pile of shapes is shown to both fields on the screen. In the middle of the section is the picture of a nude which is projected only to the left visual field. The ppt is then asked if they saw anything else other than the shapes
Results of visual investigations presented to one visual field
If an image was shown to the right visual field, the ppt would be able to say what they had seen
If it was shown to the left visual field, the ppt was unable to name it but could draw it with their eyes closed with their left hand
Results of visual investigations presented to both visual fields
The subject would be able to say they saw a key because it was presented in the right visual field, but be unaware that they saw anything else
They would be able to draw an apple through seeing it through their left visual field, they wouldn’t know they had seen something else
Results for tactile investigations
Results were the same for holding the objects in one hand and in both hands
The ppt would have no problem identifying the object by name if it was in the right hand, but if it was put in their left hand they would be unaware. They would be able to find it by touch with the left hand in a bag full of objects
When the objects were placed in one hand, the ppts could point to what the object was with the same hand which has held the object
