Biological Area studies Flashcards
Sperry - Aim, Sample, Method
Aim:
- to show the independent streams of conscious awareness possessed by each hemisphere and to show how each hemisphere has its own memories.
Sample:
- 11 patients who had undergone a Commissurotomy in an effort to control severe epileptic convulsions not controlled by medication’.
- The first patient (a man) had his surgery over 51⁄2 years before the study was conducted.
- The second patient, a housewife and mother in her 30s had her surgery more than 4 years before the study was conducted
Method:
- quasi/natural experiment
- can be considered a collection of case studies
- IV - having a spilt-brain or not
- DV - participant’s ability to perform a variety of visual and tactile tests.
Sperry - Procedure (2) and apparatus used
- Presenting visual information - The participant, with one eye covered, centred his gaze on a fixed point in the centre of an upright translucent screen.
Visual stimuli on 35-millimetre transparencies were arranged in a standard projector and were then back-projected at of a second or less-too fast for eye movements to get the information into the wrong visual field - Presenting tactile information - Below the translucent screen there was a gap so that participants could reach objects but not see their hands and objects were placed in their hands
This apparatus is called a tachistoscope.
Sperry - Results (2) and Conclusion
- Information presented to the RVF could be described in speech and writing (with the right hand). If the same information is presented to the LVF the participant insisted he either did not see anything
- Objects placed in the right hand (LH) could be described in speech or writing (with the right hand). If same objects were placed in the left hand (RH) participants often seemed unaware they were holding anything
Split-brain patients have a lack of cross-integration where the second hemisphere does not know what the first hemisphere has been doing
Casey - Aim, Sample and Method
Aim:
- To find out if ppts who were low-delayers on the marshmallow test at age 4 also reported low self-control in their 20s and 30s
Sample:
- 562, four-year-old pupils from Stanford’s Bing Nursery School completed a delay-of-gratification task
- In Experiment 1 there were 32 high delayers and 27 low delayers
- Experiment 2 were based on the performance of 26 participants.
Method:
- Quasi experiment
- Repeated measures design - some participants completed self-control scales when in their 20s and 30s and that those participating in Experiment 1 did both the “hot” and “cool” go/no go tasks
- longitudinal study - which followed some of the original participants from the age of four years
- IV - high/low delayer
- DV - the performance on the impulse control task in Experiment 1 and the performance on the impulse control task and imaging results using fMRI.
Casey - Procedure (2+2)
EXP 1
- Participants completed two versions of the go/no-go task.
- Participants were instructed to respond as quickly and accurately as possible and each face appeared for 500ms, followed by a 1-s interstimulus interval.
EXP 2
- 27 participants from Experiment 1 agreed (consented) to complete the imaging study.
- fMRI was used to examine neural correlates of delay of gratification.
Casey - Results (2) and Conclusion
- Low delayers had reduced activity in the right inferior frontal gyrus than high delayers
- Low delayers had increased activity in the ventral striatum
The capacity to resist temptation varies by context, the more tempting the choice for the individual, the more predictive are the individual differences in peoples’ ability to regulate their behaviour.
Blakemore & Cooper - Aim, Sample, Method
Aim:
- To investigate the development of the primary visual cortex (in cats) and to find out if some of its properties such as orientation selectivity are innate or learned
Sample:
- Two of the kittens (one reared in a horizontal and one in a vertical environment) were used to study neurophysical effects
Method:
- laboratory experiment which used an independent measures design
- IV - reared in horizontal/vertical lined environment
- DV - their visuomotor behaviour once they were placed in an illuminated environment
Blakemore & Cooper - Procedure (3)
- From birth in complete darkness then from age of two weeks they were put into a special apparatus for an average of about five hours per day
- routine was stopped when the kittens were 5 months old and taken for several hours each week from their dark cage to a small, well-lit room
- At 7.5 months, the two kittens were anaesthetised so their neurophysiology could be examined.
Blakemore & Cooper - Results (2) and Conclusion
- They guided themselves mainly by touch. They were frightened when they reached the edge of the surface they were standing on.
- About 75% of cells in both cats were clearly binocular
Brain development is determined by the functional demands made upon it, rather than pre-programmed genetic factors.
Blakemore & Cooper - Controls (2)
- Cat could not even see its body as it wore a wide black collar that restricted its visual field to a width of about 130 degrees
- From age of two weeks they were put into a special apparatus for an average of about five hours per day
Maguire - Aim, Sample, Method
Aim:
- to examine the direct effect of spatial experience on brain structure.
Sample:
- experimental group of 16 taxi drivers were all healthy, right-handed, male London taxi drivers, mean age 44 years and had passed The Knowledge
- The control group who did not drive taxis (50 for the VBM analysis, 16 from 50 for the pixel counting) were matched for health, handedness, sex, mean age and age range.
Method:
- quasi/natural experiment
- independent measures, matched participants design.
- IV - London taxi driver or not
- DV - volume of the hippocampi including their anterior, body and posterior regions … measured by analysing MRI scans of participants’ brain using the two techniques of VBM and pixel counting.
Maguire - Procedure (2)
The scans of the control group were selected from the structural MRI scan data base at the same unit where the taxi drivers were scanned.
The MRI scans of all participants were analysed using VBM and pixel counting to find out the volume of hippocampi
Maguire - Results (2) and Conclusion
- Taxi drivers had significantly increased grey matter volume in the posterior hippocampi compared to controls.
- Controls had a significantly greater anterior hippocampal volume than the taxi drivers.
It can be suggested that the changes in the arrangement of hippocampal grey matter are acquired i.e. due to nurture.
