The bundle of nerve fibres that
connects the two hemisphere of the
brain
Quasi-experiment
The IV in the experiment is not
manipulated, it varies naturally
Aim
Attempts to study the functions of separated and
independent hemispheres
Procedure
11 ps who had already has surgery
on their corpus callosum
Sperry did not conduct
the surgery, and the
surgery was not for the
purpose of the study
Special apparatus that allowed
info. to be presented to one
hemisphere was used
Ps vision is divided into left and right
visual feilds
Their hands were hidden
from their vision
One eye was
covered
They centered their
gaze on a designated
fixation point
Words or images
were flashed onto a
screen for 1/10 of a
second or less
Info. from the
left visual field
goes to the right
hemisphere and
vice versa
By flashing the image/word to
either the lef or right of the
fixation point the experimenter
determines which hemisphere
receives the info.
For physical tasks the
objects were placed into the
ps hands on the other side
of a screen out of view
The sensory info. is
received by only the
corresponding
hemisphere
E.g. left hand goes to right
hemisphere
The ps were
asked to find the
same object in a
grab bag with
either the same or
a different hand.
Findings
Ps act as if they have two
minds in one body
If a piece of info is sent seen by
the left visual field and goes to
the right hemisphere, it is only
reconised again if it is seen by
the same visual feild
Visual material shown
to the right visual field
sent to the left
hemisphere can be
described in speech
and writing
If the same material is then shown to
LVF, the ps insists they do not see
anything. BUT, when asked to pick the
object within a group of objects they are
able to select the correct one
If a different figure was flashed to each
hemisphere
Eg. a $ to the
LVF and a ? to
the RVF
The ps is asked to draw with their left
hand what they have seen, they will
draw they saw in the LVF ($)
But if you asked them to tell
you what they saw they
would say the object from the
RVF (?)
Objects in the right hand,
sent to the left hemisphere
can be described and named
The right hemisphere
is able to:
Select similar
items to a
target item
E.g. a watch
rather than a clock
Perform simple arithmetic operations
Understand
both written and
spoken words
Identify
objects
Understand
fairly
complex
instructions
Show appropriate
emotional reactions
Strengths
Quasi-experiment allows researchers to
investigate variables that are not able to
be investigated in a strict laboratory
experiment
The techniques Sperry developed allowed the functions of the two hemispheres to
be studied which previously had been impossible
Weaknesses
The experiment was a quasi-experiment
This does not give the experimenter complete control over the
independent variable