A2 Biopsychology - Hemispheric Lateralisation and Split Brain Research

Question 1

State functions of left and right hemispheres according to hemispheric lateralisation.

Answer 1

LH deals with language skills, whilst RH deals with visuo-spatial skills.

They work independently from one another.

Information from the left visual field (LVF) enters through the RHS of both the left and the right eye, then enters the RHS of the occipital lobe.

Question 2

Who did Sperry (1968) study?

Answer 2

Sperry (1968) studied 11 epileptic patients who’d received a commisurotomy (removal of corpus callosum to separate LH and RH)

Question 3

Describe the procedure of Sperry’s study.

Answer 3

1) Sperry (1968) presented the ppts with two different images of a different objects - one for each visual field
2) He later presented two words - key and ring - to the respective visual fields, ie key = LVF and ring = RVF
3) He finally presented different faces to the respective visual fields

Question 4

Describe the findings of Sperry’s research.

Answer 4

In 1), the ppts could only verbally describe the RVF object, as the info was sent to the LH ie language skills.

In 1), ppts could select a matching item from a bag for the LVF object (using their left hand only) as the info was sent to the RH ie visuo-spatial skills.

In 2), ppts would write key (using left hand only) as writing is a visuo-spatial skill and LVF info is sent to RH and controls LHS of body, but would say ring as RVF info is sent to LH (language skills).

In 3), LVF faces were accurately matched to photos as info sent to RH for visuo-spatial skills

Question 5

Evaluate hemispheric lateralisation.

Answer 5

(+) Allows for a quick diagnosis as we can examine what functions are lost and quickly identify which part of the brain is affected and needs to be examined

(+) Sperry’s research was very controlled as it was down in a lab environment, and he ensured that each object was in one visual field only => inc. validity

(-) Small sample size of 11 ppl, all of whom had a history of severe epilepsy; could have been the epilepsy that led to communication problems and not the commisurotomy so poor generalisability to general population

(-) Modern neuroscientists argue that the research led to an oversimplification of the functional differences between LH and RH, as we now know that LH can take over RH jobs when needed and vice versa