Sperry (classic Study)

Question 1

Lateralisation of function

Answer 1

The brain has left and right hemisphere and each hemisphere has a specific function

Question 2

Left hemisphere specialises in…

Answer 2

Language and articulation of words

Question 3

Right hemisphere specialises in

Answer 3

Emotions and creativity

Question 4

What side of the body does the left hemisphere control?

Answer 4

Right side:
Right hand
Right field of view

Question 5

What side of the body does the right hemisphere control?

Answer 5

The left side:
The left hand
The left field of view

Question 6

What part of the brain links the 2 hemispheres?

Answer 6

The corpus callosum: bundle of the nerve fibres so signals can be spread across 2 hemispheres

Question 7

Why would we cut the corpus callosum and separate the 2 hemispheres?

Answer 7

If someone had severe epilepsy: abnormal electrical impulses that cause seizures couldn’t spread across the brain if cut

Question 8

Background of this study

Answer 8

Sherry had worked on split brain cats, and knew that 1 hemisphere could be completely oblivious to something the other hemisphere was taught: so test on humans
Using epilepsy patients who had corpus callosum cut

Question 9

Aim of this study

Answer 9

Map lateralisation of brain function (aka determine function of 2 hemispheres) by presenting info to only 1 hemisphere in split brain patients

Question 10

The 3 experiments

Answer 10

Visual investigations
Tactile investigations
Right hemisphere tests

Question 11

What type of study is this and why?

Answer 11

A quasi experiment because the independent variable, whether the participant was split brained or not, was naturally occurring

Question 12

Independent variable

Answer 12

Whether participants were split brained or not

Question 13

Dependent variable

Answer 13

The responses participants had to the tactile and visual tasks given

Question 14

Experimental design

Answer 14

Independent measures: 2 categories of split brain compared to not split brain
We cannot manipulate this to be repeated measures

Question 15

Sample size

Answer 15

11 split brain patients
9 recently undergone surgery
2 had it years before

Question 16

Sample method

Answer 16

Opportunity

Question 17

The apparatus name

Answer 17

Tachiotoscope

Question 18

The set up 💯

Answer 18

Image back projected onto a screen the participant would look at
With a spot in the middle
Tactile objects behind screen out of view

Question 19

Participants were told to…

Answer 19

Focus on the spot in the middle

Question 20

When an image is presented to either side of the dot

Answer 20

Then the opposite hemisphere will internalise it and can perform actions based on its function

Question 21

Field of view meaning

Answer 21

Either the eight side of the vision or left side
This is independent of left/right eyeballs: left field of view foes to right hemisphere and vice versa

Question 22

Why project the image for 1/10 of a second?

Answer 22

To prevent eyes from moving to the image, we want to project the image to either enter the right or left field of view
We don’t want it to be the focus thus have it enter both hemispheres

Question 23

How can we ensure that the information doesn’t enter both hemispheres?

Answer 23

Have participants sit in silence, information not sent to hemisphere by outwards speech
Have participant hide hands, only opposite hemisphere can control this hand so information not transferred by visually seeing the hands

Question 24

In the visual investigations, when the image of key is shown to the right visual field what happens?

Answer 24

Information goes to left hemisphere which controls the language
So participant can say what they see, ‘key’

Question 25

In the visual investigations, when the image of key is shown to the right visual field what happens?

Answer 25

Information goes to left hemisphere which controls the language
So participant can say what they see, ‘key’

Question 26

In the visual investigations, when the image of key is shown to the left visual field what happens?

Answer 26

The information goes to the right hemisphere which controls emotions and creativity
The participant could use left hand to draw it but NOT name it

Question 27

In the visual investigations, when the image of key is shown to the right visual field but an apple is shown to left visual field what happens?

Answer 27

Info of apple is sent to right hemisphere thus they can draw it with eyes closed using left hand
Info of key is sent to left hemisphere thus they say the image they saw was of a key and have no awareness of apple
Not understand why they drew an apple

Question 28

In the tactile investigations, what happens when an object is given to the right hand

Answer 28

Information goes to left hemisphere so they could name what the object is

Question 29

In the tactile investigations what happens when an object is put in the left hand?

Answer 29

Information goes to right hemisphere so they seem to have no conscious awareness of it (cannot name it)
But can point to it and find it by touch

Question 30

Why are we Testing the right hemisphere specifically?

Answer 30

To see if the right hemisphere is able to make mental associations since we cannot use speech to show this (easy way)

Question 31

Showing simple maths problems to the left field of view

Answer 31

Info Goes to right hemisphere
The left hand was able to solve this using blocks
But not solve this verbally

Question 32

Presenting images to both visual field then showing a nude photo to the left visual field only

Answer 32

Participants could say they saw the shapes because shapes sent to both hemispheres
But showed non verbal cue eg giggle or blush when shown the nude, because nude info only went to right Visual field (controls emotions) but could not articulate why they giggled

Question 33

Evaluate ecological validity

Answer 33

Tactile tasks have high ecological validity: reaching for objects out of view may be realistic
But highly controlled set up eg covering eyes and hands, sitting in silence and being told to not move eyes and focus on one spot not reflective of real life: perhaps not accurate reflection of real life

Question 34

Evaluate population validity

Answer 34

Used a mix of genders
But only from USA: individual differences occurring within this study means we do not know of brain lateralisation and effect of commisuorotomy are species specific

Question 35

Evaluate construct validity

Answer 35

Highly controlled quasi experiment to show what we measured is due to split brain:
Hands hidden from view, sitting in silence, focus on spot, only shown for 1/10 sec, covered eyes
So no info can be transmitted to other hemisphere via the outside: we know we are measuring the function of each hemisphere