Sperry (1968) - Split-Brain

What was the aim of the study?

To investigate the effect of hemisphere deconnection (corpus collosotomy/ Split-Brain operation) and to further understand the functions of the right and left hemisphere

What type of experiment was it?

Quasi experiment (IV is naturally occurring)

What was the method for the first test?

One visual field test

One stimulus shown at a time to one visual field. Then they had to name the object and find it with their right/left hand

What were the results from the first test?

Image shown to RVF: can name image and recognise object with right hand from an array of objects

Image shown to LVF: can draw object and recognise with left hand, but NOT name the object

What was the second test?

Touch test, participants could not see their hand or the object they were given to hold

What were the results for the second test?

Object placed in right hand: can name and describe object, but CANNOT locate the object with the left hand

Object placed in left hand: CANNOT name or describe object, CANNOT locate object with right hand

What was the third task?

The participants were shown the object visually and had to find it blindly with left/right hand

What were the results for the third task?

Image shown to RVF: can find using right hand, but NOT left hand

Image shown to LVF: can find using left hand, but NOT right hand

What was the forth task?

Nude image was flashed to the LVF (right hemisphere), participants asked what they saw

What were the results for the forth test?

Participants were seen blushing and giggling, but seemed unable to verbally describe what they had seen. This is believed to because the right hemisphere cannot produce speech. They were also unaware of why they had these reactions as they could not comprehend what they had seen.

Who were the participants?

11 people of both genders, 2 had the surgery performed long before the experiment whereas 9 had recently had it

What was the IV?

Presence or absence of a split-brain (Sperry did NOT do this himself)

What was the DV?

Whether participants could name, recognise, and draw objects

What conclusions were drawn?

Most patients dominant hemisphere was the left

The severing of the corpus collosum stops the two hemispheres from connecting