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Flashcards in Sperry 1968 Deck (19):

What did he want to prove

To investigate both the localisation and lateralization of brain functions

To test the effects of a severed corpus callosum, and therefore prove that the two hemispheres have separate functions


How many participant and what did they have to have? and why did they have it?

11 patients
who had severed corpus callosums,
where the corpus callosums were severed in epilepsy sufferers to prevent seizures crossing from one side of the brain to another.


What did they patients have to do?

The patients were asked to perform hemisphere-related tasks

being shown an image on the left or right hand side of their body, where they were asked to identify it or asked to drawn pictures with their left or right hands based off an example.


What did Sperry find when picture was shown on the left visual field (right hemisphere)

the participant insisted he either did not see anything or that there was only a flash of light on the left side, that is, the information could not be described in speech or writing.

However the participant could point with his left hand (controlled by the right hemisphere) to a matching picture / object presented among a collection of pictures / objects.


When shown on the right?

Inversely, when the object was shown on the right the patients were able to identify what it was.


Strengths of the study

Although he only had 11 participants

significant insight on brain localisation and lateralization.


Limitations of the study

Low ecological validity because only 11 participants

more research for people who do not have a severed corpus callosum, so it can be distinguished if relevant for general population


Conclusion drawn about lateralization of function

Lateralization of function include the assertion that the right half of the brain is dominant for visuo-spatial ability

(demonstrated in tasks like reading maps or recognizing faces),

as well as musical abilities and understanding intonation in speech.


Conclusion drawn about left side of brain

The left half of the brain seems to be more positive than the right and is dominant for language and logical or mathematical abilities.


What did his research enable

allowed other research to form and take place to gain more insight into how the different parts of the brain functions.


which hemisphere of the brain is language processed



what kind of experiment and measure design did sperry use?

used a quasi experiment in a laboratory with an independent measures design.


Why did the participants have to wear an eye patch?

Wearing an eye patch and staring at the focal point were controls. These controls ensure that stimuli was presented only to the desired visual field.


Why were the visual stimuli only presented for 0.1s?

. This was another control as it is too quick for eye movements to cause visual information to enter both visual fields.


When could the participants recognise the stimuli?

Participants would only recognise stimuli if the stimuli was presented again to the same visual field. If participants were shown stimuli in the right visual field, but then shown the same stimuli to the left visual field, they would claim to have not seen it before.


What did sperry find when shown on the right visual field?(left hemisphere)

could be described in speech and writing (with the right hand).



study used a quasi methodology, Sperry did not need to manipulate anything, which is more ethical than studies which manipulate variables.


control group

Sperry did not use a control group, which makes it difficult to truly establish cause and effect.

However, it is important to note that in this study a control group was not needed as the results of the tasks for people without split corpus callosums were already known.


external validity

may be considered low because the stimuli was selectively delivered to one hemisphere.

This does not happen in real life and thus is not representative of the everyday experience of ‘split-brain’ patients.

However this selective presentation of stimuli increased the internal validity because there is an increased likelihood that Sperry measured the effects of hemisphere deconnection