Split brain research This week Split brain Ways

Split brain research

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

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)

Starter Write 2 questions on a post-it note to challenge another student’s knowledge of… 1) Biopsychology 2) Content that you covered in first year

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

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: 1. What do the following terms mean: corpus callosum and hemispheric lateralisation. 2. What is a commissurotomy 3. What is the aim of split brain research? Why do people have the surgery?

language Visual motor tasks 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

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

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)

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.

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!

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.

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. 1)Describing what you see 2)Drawing tasks 3)Tactile tasks 4)Composite words

Sperry split brain research https: //www. youtube. com/watch? v=lf. Gws. Ad. S 9 Dc https: //www. youtube. com/watch? v=82 tl. Vcq 6 E 7 A&feature=related++Split+Brain+Patients++Joe

Sperry’s findings Sperry conducted a number of different variations alongside a number of different findings. 1) 2) 3) 4) 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.

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

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

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.

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

Composite words TWO different words displayed e. g. KEY and RING Describe what is happening in this picture.

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.

Recognition by touch Tactile tasks (could not see objects) Right Hand = Objects could be named. Why? 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

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.

Consolidation Task 1)Complete page 37 in your pack 1)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

Evaluation of Split Brain Research • Use of specialist equipment. • Use of standardised procedures • Practical applications • 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.

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 (1/10 th of a second). Why so fast? (-) What could be said about the study’s population validity & generalising the results?

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.

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.

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 visualmotor 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.

Evaluation 1) Write a detailed evaluation point of split brain research on a point that we have discussed. 2) 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 AO 3 point? Make these in green!

Exam focus Q 1. 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] Q 2. Briefly evaluate research using split brain patients to investigate hemispheric lateralisation of function. [4 marks] Q 3. Discuss hemisphere lateralisation including research into split brain patients (16 marks)

Possible answers – Q 1 • 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

Possible answers – Q 2 • 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