sperry

Background and aims

2 hemispheres of the brain connected by corpus callosum

Hemisphere deconnection:

Split brain operation - cutting through connection between the 2 hemispheres

Can help with severe epilepsy as electrical storms cannot travel through hemispheres

Aim: record the psychological effects of hemisphere deconnection in patients with severe epilepsy

Understand how right and left hemisphere work in “ normal “ individuals.

Method

Controlled observation

Snapshot study

Quasi experiment - IV is split brain or not

Sample

11 split brain patients

Opportunity sample- patients referred to white memorial centre in LA

Materials

Abilities tested using a tachistoscope - device that displays images for a specific amount of time l.

Procedure

One eye covered and participants asked to look at cross in middle of screen

Images flashed on screen for 0.1 second

tasks designed to test right and left hemispheres responses from LVF and RVF and left and right hand

Tasks used:

Verbal: composite word shown e.g keycase so key is in LVF and case is RVF - patients asked to report the word

Verbal: image shown to LVF or RVF and patients had to name image

Recognition: imagine shown to LVF or RVF and patients had to indicate recognition of object

Tactile: image shown to LVF or RVF and patient has to identify the same object with one of their hands

Dual- processing task: 2 objects placed simultaneously one in each hand, then hidden in a pile of objects. Each hand has to recognise objects

Results

If $ displayed to LVF and % to RVF participants can say they saw % which shows RVF linked to left hemisphere which is responsible for language

Can draw $ with left hand shows LVF is linked to left hand which are both linked to right hemisphere

Image shown to RVF ppt can say what they saw but if shown to LVF ppt said they saw nothing or a flash of light ( processed by right hemisphere)

Dual processing task- can only find the object that was in the same hand

Composite words : key case - selected a key with left hand but spells “ case “ with right hand

Touch: objects in right hand can be named ( processed by LH )

If object placed in left hand ppts said their hand wad numb or that they guessed.

Conclusions

Functions are lateralised in the brain

Right hemisphere is silent as it cannot respond verbally