1. Split brain research

2. This week Split brain Ways of studying the brain (mark exam paper)
Research methods (essay)

3. Homework
Section B: Complete the essay on page 48 focusing on the content we learnt today and last week.
Section A:
Revision schedule:
Paper 2 (Biopsychology, approaches, rm)

4. Starter
Write 2 questions on a post-it note to challenge another student’s knowledge of…
Biopsychology
Content that you covered in first year

5. Objectives To be able to…
Describe and evaluate Sperry’s split brain research
Apply this knowledge to an exam question

6. Starter (page 38)
Get yourself in to group of 3’s. assign yourself a number between 1-3.
Using your textbook/pack/ internet answer your question:
What do the following terms mean: corpus callosum and hemispheric lateralisation.
What is a commissurotomy
What is the aim of split brain research? Why do people have the surgery?

7. Visual motor tasks language
Remember Broca? He found that damage to a particular area of the left brain hemisphere lead to language problems, yet damage to the same area in the right side did not have the same consequence

8. The left and right side communicates through the corpus callosum
The corpus callosum is a bundle of nerve fibres which joins the two halves of the brain
A commissurotomy is the division of the two hemispheres by surgery, which has occasionally been done to improve epilepsy
The left and right side communicates through the corpus callosum

9. Hemispheric Lateralisation
The idea that the two halves of the brain are functionally different and certain processes or behaviours are controlled by one hemisphere rather than the other.
The RIGHT side of the brain processes info from LEFT half of body (e.g. visual info from the left eye)
The LEFT side of brain processes info from RIGHT half of body (e.g. visual info from the right eye)
Language

10. Who are split brain patients?
A unique group of patients who had a Commissurotomy – where the Corpus Callosum is severed so that the two hemispheres are separated and don’t communicate with each other.
This was done to control frequent and severe epileptic fits.

11. Sperry’s Split Brain Experiment (1968) was:
A quasi experiment.
11 participants
Sperry’s Ps were epileptics who could not be treated with drugs. They had ALREADY HAD their corpus callosums split. No ethical issue there then!

12. KEY STUDY: Sperry (1968) PROCEDURE:
The participant gazes at a fixation point on an upright translucent screen
slides (a word or picture) are projected either side of the fixation point (into one visual field or the other) at a rate of one picture per 1/10 second
This is then dealt with by the opposite hemisphere of the brain and the information isn’t shared between the two hemispheres.
The method used was a natural (also called quasi) experiment. The quasi-experiments involved comparing the performance of the 11 participants on various tasks with the performance of people with no inter-hemisphere deconnection. The independent variable was therefore the whether a person had hemisphere deconnection or not and the dependent variable was the participants performance on the tasks.

13. Sperry’s procedure
This is a T scope (tachistoscope). P focuses on central point of screen and image or word is flashed to one or both visual fields.
Describing what you see
Drawing tasks
Tactile tasks
Composite words
This is a T scope (tachistoscope). P focuses on central point of screen and image or word is flashed to one or both visual fields. They then will be asked to do several tasks, including saying what they saw or picking up objects that are hidden from view (as seen in picture).

14. Sperry split brain research

15. Sperry’s findings
Sperry conducted a number of different variations alongside a number of different findings.
Describing what you see
Tactile tasks
Composite words
Matching faces
The following slides are recapping some of the key findings.
These can be tricky to get your head around but hopefully by the end of this task you will feel more confident.
The activities to follow are designed for them to get their heads around the research findings as it can be mind-bendy!

16. Can you point to (with your left hand) what you saw?
Imagine you are one of Sperry’s split brain patients
RVF
LVF
Can you point to (with your left hand) what you saw?
Left
Hemisphere
Right
Hemisphere
What did you see?
……………..

17. Imagine you are one of Sperry’s split brain patients
RVF
LVF
Left
Hemisphere
Right
Hemisphere
What did you see?
A happy face!

18. Findings: Drawing
A picture is shown to the left or right visual field and the patient is asked to draw it. The drawings were consistently better when drawn by the left hand (controlled by the right hemisphere) This was despite the patients actually being right handed.
This suggests that the right hemisphere (and therefore left hand) was superior at drawing ability.

19. Draw (with your left hand) what you saw.
$ ?
RVF
LVF
Draw (with your left hand) what you saw.
Left
Hemisphere ?
Right
Hemisphere $
What did you see?
A question mark $

20. Composite words TWO different words displayed e.g. KEY and RING
Describe what is happening in this picture.
When two different words are displayed at the same time the split-brain participant will be say they saw the word ring but when asked to pick up the object they saw with their left hand will pick up a key.

21. Findings: Composite Words
Composite words: If two words were presented simultaneously, one on either side of the visual field (for example key to left visual field and ring to the right visual field)
They would say ring and they would be able to pick up the key with their left hand.
They would say ring as that is processed by the left hemisphere and they would be able to pick up the key with their left hand as that was processed by the right hemisphere

22. Recognition by touch Tactile tasks (could not see objects)
Right Hand = Objects could be
named. Why?
As speech is processed in left hemisphere it can only be named by the p when picked up with the right hand.
Left hand = Objects could not be
named. Why?
However, Left Hand could pick out the object
When it was placed with others in a grab bag

23. What can we conclude from Sperry’s research?
The left hemisphere is dominant in terms of speech and language. The right hemisphere is dominant in terms of visual-motor tasks.

24. Extension: complete page 39 in your pack
Consolidation Task
1)Complete page 37 in your pack
Complete separate handout outlining sample and procedure and applying your knowledge of hemispheric lateralisation, explain WHY the findings occurred.
Extension: complete page 39 in your pack

25. Evaluation of Split Brain Research
Issues with control group
Data came from artificial situation
Small samples used.
Lateralisation and functions are not as clear cut (Lang/non lang is a basic distinction) – some functions can be shared by different areas of the brain through constant communication. E.g. during functional recovery. Lateralisation is overestimated.
Use of specialist equipment.
Use of standardised procedures
Practical applications
Evaluation activity.
Discuss with learners strengths and weaknesses of methodology. In pairs, they have to choose at least one strength and one weakness and write a P.E.E.L paragraph on whiteboards. Once done, ask the students to consider which they think would be awarded the most marks and why.

26. Support Evaluation of Sperry’s Split Brain Patients Study
(-/+) The method was a ________________________________ in controlled conditions. What are the strengths and weaknesses of the methods used?
(+) It was flashed very quickly (1/10th of a second). Why so fast?
(-) What could be said about the study’s population validity & generalising the results? 

27. Sperry: Methodological Evaluation
Quasi Experiment
Strengths: controlled conditions – standardised procedures (good internal reliability)
Weaknesses: lack of ecological validity – in real life the patients can adjust visual position so info goes to both hemispheres
Fast presentation meant the patient didn’t have time to move their eye across to process the image with the other eye.
Population validity: Sample was 11 patients – may not be a large enough sample to generalise. Also it may be inappropriate to make generalisations about non-epileptic brain patterns from these patients. The epileptic seizures could have made changes to the brains that could have affected the findings.
Quasi Experiment
Fast presentation meant the patient didn’t have time to move their eye across to process the image with the other eye.
Procedure allowed Sperry to vary small aspects and see the effects
Procedures were standardised – good internal reliability.
Issues – low ecological validity as it was a controlled setting and in real life the patient can shift their focus so information is processed by both hemispheres. Little control of EV’s in the participants
Sample size – small with only 11 patients. Also difficult to generalise to non-split brain patients as they were epileptic and this could have led to changes in the brain over non-epileptics.
Methodological evaluation. Sperry’s research was very well designed and employed well thought through standardised procedures. As he made use of presenting information to one eye whilst the other was blindfolded and he flashed the image up extremely quickly he had properly controlled which hemisphere was being exposed. He also designed a procedure which could be replicated so his findings could be validated.
The split-brain procedure is rarely carried out these days. Therefore patients who have had this procedure are rarely encountered in sufficient numbers to be useful for research. Andrewes (2001) argues that many studies have only 3 (sometimes even just 1 ppt). Therefore he claims conclusions have been drawn from individuals who have either a confounding physical disorder that made the procedure necessary or who had a less complete sectioning of the 2 hemispheres than was originally believed. Andrewes claims that these ‘rogue’ cases are often only identified when the results of a study have failed to be replicated.

28. Evaluation
Gazzaniga (1998) suggests that some of the early discoveries from split-brain research have been disconfirmed by more recent discoveries. E.g. split brain research had suggested that the right hemisphere was unable to handle even the most rudimentary language. However, case studies have demonstrated that this was not necessarily the case. One patient (J.W.) developed the capacity to speak out of the right hemisphere, with the result that J.W. can now speak about info presented to the left or to the right brain. This suggests that…
Language may not be exclusively limited to the left hemisphere. It also supports brain Plasticity as before his surgery (callosotomy) he had language dominant left hemisphere so it shows the brain can recover functions.
Split brain patients who are initially unable to produce speech in their right hemispheres sometimes develop the ability to do so. Patient J. W., the subject of this report, is such a patient. At the time of his callosotomy, J.W. had a language dominant left hemisphere; his right hemisphere could understand both spoken and written language, but he was unable to speak. Fourteen years after his surgery, we found that J. W. was capable of naming 25% of the stimuli presented to his left visual field (LVF). Now, 1 year later, we find that he can name about 60% of such stimuli. This latedeveloping speech ability appears to be the consequence of long-term neural plasticity. However, the subject's extended verbal responses to LVF stimuli seem to result from a collaboration between the hemispheres and to involve the left hemisphere interpreter.

29. Other Evaluation
Split brain patient work has provided a considerable amount of research into lateralisation of brain functions. It shows the left is more centred on verbal and analytical tasks and the right more on visual-motor and creative tasks.
However…
One legacy of work into lateralisation of function is the growing amount of pop-psychology literature which over emphasises (and simplifies) the differences between the hemispheres.
In truth the differences between the two are a lot more intricate. Far from working in isolation the two hemispheres form a highly integrated system and are both involved in most every day tasks.
A different point:
It’s generally assumed that the main advantage of brain lateralisation is that it increases neural processing capacity. By using only one hemisphere to engage in a particular task (e.g. language or mathematical ability), this would leave the other hemisphere free to engage in another function. However, despite this assumption, very little empirical evidence has been provided to show that lateralisation confers any advantage to the functioning of the brain, Rogers et al (2004) found that, in the domestic chicken, brain lateralisation is associated with an enhanced ability to perform two tasks simultaneously – finding food and being vigilant for predators. This finding does provide some evidence that brain lateralisation enhances brain efficiency in cognitive tasks that demand the simultaneous but different use of both hemispheres.

30. Evaluation
Write a detailed evaluation point of split brain research on a point that we have discussed.
You will then speed date/swap with each other – enabling your ‘date’ to collect your evaluation point. 3 minutes at each date. When the bell rings find another date.
Challenge: Whilst ‘dating’ can you suggest or make improvements to the effectiveness of your date’s AO3 point? Make these in green!

31. Exam focus
Q1. Split brain patients show unusual behaviour when tested in experiments. Briefly explain how unusual behaviour in split brain patients could be tested in an experiment. [2 marks]
Q2. Briefly evaluate research using split brain patients to investigate hemispheric lateralisation of function. [4 marks]
Q3. Discuss hemisphere lateralisation including research into split brain patients (16 marks)

32. Possible answers – Q1
plausible experimental situation/set-up – eg split visual field
plausible stimulus – visual, faces, words, auditory, digits, music etc
plausible task for patient – verbal or visuospatial response, eg drawing, matching etc

33. Possible answers – Q2
The comparison groups were not considered to be valid as they were often people with no history of epileptic seizures
The data were artificially produced as in real life a severed corpus callosum can be compensated for by the unrestricted use of two eyes
Research relates to small sample sizes.
The research has added to the unity of consciousness debate