Biopsychology: topic 9 ‘research into hemispheric lateralisation and split brain’

Question 1

what surgical treatment did the participants in Sperry’s studies undergo? why?

Answer 1

• cutting the corpus callosum connecting the two hemispheres
• this surgical procedure was performed to control severe epilepsy

Question 2

how many split-brain patients were involved in Sperry’s study?

Answer 2

• 11 split-brain patients
• the same number of participants was used in the control group of non split-brain patients

Question 3

what was the main task given to the split-brain patients during the study?

Answer 3

• to focus on a dot in the center of a screen with one eye blind folded while images or words were projected to each visual field

Question 4

what happens when an object is shown to the right visual field of split-brain patients?

Answer 4

• the patient can easily describe what was seen

Question 5

what happens when an object is shown to the left visual field of split-brain patients?

Answer 5

• the patient cannot describe what was seen and reports that there is nothing there

Question 6

why can split-brain patients not describe objects shown in their left visual field?

Answer 6

• because language is processed in the left hemisphere, while the right hemisphere lacks language centers

Question 7

fill in the blank: In Sperry’s study, images projected to the left visual field are processed by the _______

Answer 7

• right hemisphere

Question 8

fill in the blank: In Sperry’s study, images projected to the right visual field are processed by the _______

Answer 8

• left hemisphere

Question 9

true or false: Sperry’s studies involved patients who had not undergone any surgical treatment

Answer 9

• false

Question 10

what was the purpose of cutting the corpus callosum in the patients?

Answer 10

to control their severe epileptic seizures

Question 11

what do the findings of Sperry’s research allow us to infer about normal brains and the use of the corpus callosum?

Answer 11

• left hemisphere is responsible for language and speech
• right hemisphere has no language centres

Question 12

recognition by touch - what ability did patients demonstrate when objects were projected in their left visual field?

Answer 12

• patients could select a matching object using their left hand
• this ability is linked to the right hemisphere of the brain

Question 13

how were the objects presented to the patients during the recognition by touch experiment?

Answer 13

• the objects were placed behind a screen so as not to be seen

Question 14

what was an example of an object selected by the left hand in response to a visual stimulus?

Answer 14

• an ashtray was selected in response to a picture of a cigarette

Question 15

could patients verbally identify the objects they saw in their left visual field?

Answer 15

• no, patients were not able to verbally identify the objects

Question 16

which hemisphere of the brain is responsible for understanding objects projected in the left visual field?

Answer 16

• the right hemisphere

Question 17

fill in the blank: patients could not attach verbal labels to objects projected in their _______ visual field

Answer 17

• left

Question 18

true or false: the left hand was unable to select an object that was most closely associated with an object presented to the left visual field

Answer 18

• false

Question 19

what does recognition by touch allow us to infer about normal brains and how they are structured?

Answer 19

• shows that we are contra-laterally controlled: right hemisphere controls left side of the body and left hemisphere controls right side of the body
• RVF goes to the LH and LVF goes to RH

Question 20

composite words - what happens when two words are presented simultaneously in the visual field?

Answer 20

• the patient may say one word but write the other with their opposite hand
• this phenomenon demonstrates the split-brain effect where the two hemispheres of the brain process information differently

Question 21

composite words in the example given (‘face’ on the left and ‘key’ on the right) which word did the patient say?

Answer 21

• ‘key’
• ‘key’ was presented on the right side of the visual field, which is processed by the left hemisphere responsible for speech

Question 22

which word did the patient write with their left hand?

Answer 22

• ‘face’
• the ‘face’ was presented on the left side of the visual field, processed by the right hemisphere, which controls the left hand

Question 23

fill in the blank: If the words ‘face’ and ‘key’ are presented simultaneously, the patient will say ‘_____’ and write ‘_____’

Answer 23

• ‘key’, ‘face’
• this illustrates the disconnect in processing between the two hemispheres of the brain

Question 24

true or false: In split-brain patients, both hemispheres can communicate freely with each other.

Answer 24

• false
• the lack of communication between hemispheres is a characteristic of split-brain conditions

Question 25

composite words - why is it the case that the patient would say ‘key’ and write ‘face’ with their left hand?

Answer 25

- shows that the LVF goes to the RF which controls left side of the body (can draw or pick up an object in LVF) - shows that the RVF goes to the LF which has language centres and so they say the word presented in the RVF