Discuss Sperry’s research into split brain research Flashcards
Summary
In a laboratory experiment using a repeated measures design, Sperry asked 11 split brain participants to face a screen, focusing on a central fixation point.
presented with words or images (for 1/10th of a second) in their left or right visual field, before reporting what they had seen. Due to the short presentation time and their divided visual field, Sperry could be confident that information presented in the right visual field was processed in the left hemisphere, without being shared with the other hemisphere, and vice versa.
From this research, he was able to establish the hemispheric lateralisation of particular functions. In the first variation, participants were presented with words in their left visual field and were asked to identify (by touch) the correct item from a collection of objects using their left hand.
Participants were able to identify by touch the correct item, however, they could not report having seen the word and were unable to explain why they had selected the object.
In the second variation, participants were presented with words in their left visual field and were asked to write the word using their left hand.
Participants were able to correctly write the word they had been shown, despite no being able to verbally report having seen a word.
In the third variation. Participants were presented with images of shape in their left or right visual field, before being asked to draw it.
Participants were able to accurately draw images presented in their left visual field but unable to draw images presented in the right visual field.
In the 4th variation, participants were presented with images of faces in their left or right visual fields, before being asked to identify the face from a selection.
They were able to identify the correct fave when it was presented in the left visual field but were unable to identify it when presented in the right visual field.
Limit 1
Low external validity
Which is when it is difficult to generalise the findings to wider populations
This is because sperry’s research only used 11 patients with brain damage
Therefore, it is hard to make generalisation to neurotypical participants, who make up most of the wider population
However, in defence of sperry’s research, it would have been impossible to overcome this issue as so few commissurotomy patients exist
Limit 2
Has extraneous variables
Which is when a study has not controlled fro all variables that could affect the DV, decreasing the internal validity of research
This is because some patients had experienced drug therapies to reduce their epileptic symptoms for much longer than other patients
Therefore, we cannot be certain that it was the commissurotomy that was causing the results in sperry’s research
Limit 3
High individual differences
Because variation between the split-brain participants were not properly controlled
This is because the disconnection between hemispheres was greater in some patients than in others before their commissurotomy
These differences may have undermined the internal validity of research into hemispheric lateralisation
