Physiology Psychology - Sperry (1968)

Robyn Chamberlain
Mind Map by , created over 5 years ago

A-Level Psychology (AS - 15 Core Studies (OCR)) Mind Map on Physiology Psychology - Sperry (1968), created by Robyn Chamberlain on 03/17/2014.

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Robyn Chamberlain
Created by Robyn Chamberlain over 5 years ago
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Physiology Psychology - Sperry (1968)
1 Background
1.1 The brain is made up of two hemispheres, the left and the right. These two hemispheres are connented by the Corpus Collosum.
1.1.1 The left hemisphere is the 'logical' side. It processes numbers, sequences, language (both to apprehend and to speak) and uses logic to reason events out.
1.1.2 The right hemisphere is the 'creative' side which processes whole imagery, patterns, spatial awareness and music.
1.1.3 The Corpus Collosum is a bundle of nerves which connects both hemispheres together, allowing information processed from one side of the brain to relay into the other side.
2 Aim
2.1 The aim of this study was to investigate how the effect of hemisphere deconnection and to show each hemisphere has different functions.
3 Sample/Participants
3.1 11 participants who had undergone the sugery which severs the Corpus Callosum.
3.1.1 Only two of these were described in detail.
3.1.1.1 The first - A male who had had been suffering from seizures for more than 10 years, an average of two major attacks per week before beggining to suffer reccuring seizure which were at a high death risk. Since having the surgery, the participant has had no seizures and had significantly reduced his medivation and reported an overall improvement in health.
3.1.1.2 The second - A female in her thirties who reported that she was also seizure free since the operation which was four years prior. The EEG scan she had was reported to have a normal pattern.
3.1.1.3 Based on the sucess of the first two patients, the surgery was extended to the other nine also used in this study.
4 Procedure/Method
4.1 Quasi-Experiment

Annotations:

  • The participants had had the surgery before the study, Sperry took no part in it - The independant variable had not been manipulated.
4.1.1 Laboratory Experiment
4.2 1) Sperry used a specially designed apparatus that allows information to reach only one hemisphere.
4.3 2) Images flashed on the screen for 1/10 of a second so that information could not be seen by the other hemisphere.
4.4 3) The stimulus (the images or words) would be placed either left or right the fixation point at the centre of the screen and participants would be asked to say or draw whet they saw.
4.5 Tactile Tasks - Objects would be placed in one of the subjects hands (screened from view) and then, after the item had been removed from the participants hand, were asked to take the same item from from a bag with the same/alternative hand.
5 Controls
5.1 The same image was shown to each participant.
5.2 Length of time shown was the same for each participant.
5.3 Same experimenter used.

Annotations:

  • Possibility of different interpretations/obervations are lessoned.
5.4 Same object is placed in each participants hand.
6 Results/Findings
6.1 Type of Data
6.1.1 Quantitatve

Annotations:

  • The majority of this study is quantitatve data. -Sperry records whether something can be identified or not which allows him to make later conclusions about how the two hemospheres differ in their functions.
6.1.2 Qualitative

Annotations:

  • The qualitative data that Sperry recorded were the experiences of the 'split-brain' patients which add significantly to the attempt to understand why/how thier experiences occured.
6.2 1) Images shown in one half of their visual field and then presented with the same image in the other half of the visual field responded as if they had never seen the image before.
6.2.1 If the same image was presented in the original visual field the participants were able to recognise the image as one they had seen before.
6.3 4) Right hand + Object = Speech
6.3.1 Left hand + Object = Inability to speak - but ability to find the object again in the grab bag.
6.3.2 Right hand side could also:
6.3.2.1 Select similar items, E.g. Clock - Watches.
6.3.2.2 Can perform simple arithmetic operations.

Annotations:

  • Arithmetic operation - A mathematic operation involving numbers.
6.3.2.3 Can understand both written and spoken word, but cannot be understood.
6.3.2.4 Can identify objection but cannot be verbally speak them.
6.3.2.5 Can understand instructions
6.3.2.6 Show emotion
6.4 3) 2 Symbols shown simultaneously (e.g. a dollar sign (LVF) and a question mark (RVF)), draw the left (dollar sign) and say the right (question mark).

Annotations:

  • RVF - Right visual field LVF - Left Visual field
6.5 2) Left visual field - Participants could not talk of the image if shown on the left hand side of the visual field.
6.5.1 They could respond non-verbally by pointing with their left hand to the matching picture of selecting an object presented among a collection of other pictures and objects.
6.5.2 This only works with right-handed oarticipants.
7 Strengths
7.1 High controls

Annotations:

  • Over the extranuous variables.
7.2 Ethics

Annotations:

  • No ethical issues were breached during this study.
7.3 Representivity

Annotations:

  • Of the small amount of people who have had the operation.
7.4 Quasi-Experiment

Annotations:

  • Allowed the researchers to investigate the variables in strict laboratory conditions. (The functioning of the two brain hemispheres have never been studied in such depth before)
7.5 Reliability

Annotations:

  • Can be replicated with new split-brain patients.
8 Weaknesses
8.1 Ability to be generalised

Annotations:

  • The small sample of 11 means it cannot be generalised to the whole public - seeing as spilt-brain patients are not a common thing - it is not suprising.
8.2 Quasi-Experiment

Annotations:

  • The fact it was a quasi-experiment meant that the experimenter had no control over the independant varibles.
8.3 Low Ecological Validity

Annotations:

  • The procedure Sperry uses, seperating the two visual fields is something unlikely to occur in real life and if it did - The split brain patients have methods which allow them to cope with such events.
  • However, ecologically valid research is studying real problems, which is something Sperry does - Looking at the naturally occurring variable of the results of the split-brain surgery is studying the real life problem. Attempting to understand the effects of the proceedure and if the operation should be any cause for concern for the individuals undergoing it.
8.4 Furthur Validity

Annotations:

  • May not be able to compare 'split brain' (severe epilectic brain) to a normal brain.
9 Usefulness
9.1 This study had been deemed very useful as it revealed facts about the lateralisation of the functions between the two hemispheres that had only been suggested by previous studies.
10 Conclusion
10.1 Both hemisphere's have their own functions
10.1.1 The left is responsible for language and the right side of the body.
10.1.2 The right side is responsible for spatial awareness and the left side of the body.

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