Sperry, R. (1968) Hemisphere De-connection and
unity in Consciousness. American Psychologist. 23.
723-733. Classical Study
Context
The Corpus Callosum is a bundle of nerve fibres that acts as a bridge,
connecting the two Hemispheres together. This allows for the
transmission of information to be passed from one hemisphere to
the other. Without this, information would be stuck in one
Hemisphere.
Epilepsy is a neurological condition that causes seizures – electrical
storms that cause neurons to fire – it causes a seizure due to too
much information being passed. Therefore it causes a shutdown,
similar to a circuit breaker with surge protection or overloading a PC
for it to crash. It is not known why Epilepsy occurs.
Seizures can be reduced without the Corpus Callosum as there is no
longer a bridge connecting the two Hemispheres. Ergo the ‘split
brain’ procedure was birthed. However, this procedure is only used
on patients who don’t respond to drug therapy.
Vogal and Bogan tried this on 24 patients – they found that the
seizures were reduced but didn’t have an effect on IQ, etc.
Sperry had originally performed the ‘split brain’ procedure on
ANIMALS to find out how it affected people. But now Sperry used
patients from Vogal and Bogan to test what they could do.
, Aim
To investigate the effects of
Hemisphere De-connection and to
further understand the functions of
the Left & Right Hemispheres.
Method
This study can be considered a Quasi
Experiment; however, this study is
also a series of Case Studies, ergo,
the study can ALSO be considered a
series of Case Studies. As the research involved intensive study of 11
patients to investigate their behaviour symptoms resulting from the
Hemisphere De-connection. The Independent Variable is naturally
occurring which is the presence or absence of a split brain. Sperry
however DID NOT perform the split-brain operation. The Dependent
Variables were whether the participant could name objects,
recognise objects, and draw objects.
Participants
There were 11 participants (male and female) who had already had
the split-brain operation to disconnect the Two Hemispheres. All
participants suffered from severe epilepsy which had not responded
to drug therapy and were right-handed. 2 of the patients had
undergone the surgery SOMETIME BEFORE the experiment. The
remaining 9 had RECENTLY UNDERGONE the surgery.
Procedure and Results
Sperry designed equipment (the
tachistoscope) that allowed information to be
presented to just One Hemisphere – the
participants’ vision is divided into Left &