Biological Flashcards
aim of sperry
to show each hemisphere has an independent stream of conscious awareness and own chain of memories and to reaffirm what we understand about the function of the two hemispheres
method and sample of sperry
quasi, 11 pps all have severe epilepsy and a commesurectomy to control epileptic seizures
visual procedure of Sperry
one covered, gaze centered at translucent screen. stimuli shown at1/10th of a second via projector. anything projected on the left of the screen was visible only to the left visual field and anything projected to the right was visible to the right visual field
tactile procedure of Sperry
below a screen was a gap so pps could reach objects but not see them. info of objects placed in left hand was processed via the right hemisphere and info of an object placed in the right hand was processed via the left hemisphere. pps had to describe what the object was or finding the object. the screen is a tachistoscope.
results of the visual test of Sperry
info presented to one visual field is identified by the same VF. info presented to the RVF was sent to the left hemisphere so pps could describe in speech or writing what the object was.
info presented to the LVF was sent to the right hemisphere and could be pointed out with the left hand and say they only saw a flash of light/
results of the tactile tests of Sperry
object placed in right had was described in speech and writing. if the same object was placed in the left hand pps would make a guess. objects felt in one hand were recognised by the same hand.
conclusion of Sperry
hemispheres are independent and have their own chain of memory which are inaccessible to the other
strengths of Sperry
+ lab enviroment, controlled setting, establish cause and effect
+ useful, provides us with further knowledge about the brain and how it functions
weaknesses of Sperry
- isnt genralisable, results cant be applied to society as the findings only apply to those which have had a commesurectomy
- small sample, only 11 pps not big enough to be considered representative of the target population, cant apply results
aim of Casey
to test if ability to delay of gratification in childhood is the same as an adult and to see the neurological parts which correspond to delay of gratification
design, method and sample of Casey
quasi longitudinal experiments.
562 in background study
117 contacted
59 in E1
26 in E2
procedure of experiment 1 of Casey
at home with preprogrammed laptop, hot and cool task. must press a button (go) or not press a button (no-go)
cool= one sex is go, other is no go. faces were neutral
hot= the same but faces were fearful or happy
procedure of experiment 2 of Casey
pps were in a fMRI scanner whilst completing only the hot task
results for experiment 1 of Casey
98% correct in cool task
99.5% correct in hot task
low delayers had less accuracy with the no go
results for experiment 2 of Casey
98.2% accuracy in go
87.6% accuracy of low delayers in no go
low delayers had elevated activity in the ventral stratum
high delayers had elevated activity in the right inferior frontal gyrus
conclusions of Casey
ventral stratum is the reward center
right inferior frontal gyrus withholds gratification
strengths of Casey
+ internal reliability, controlled setting in E2, sure of cause and effect
+longitudinal design, allows behaviour to be tracked overtime and compared without the effect of individual differences
weaknesses of Casey
- lacks ecological validity, procedure doesnt represent real life, results arent generalisable
- lacks population validity, sample are all from the same nursery, people from other nurseries may not fit the results and conclusions are made
4 assumptions of the biological approach
- our behaviour and experiences is determined by our biology
- our behaviour is controlled by our brain and CNS through hormones and neurotransmitters
- people are biological machines
- we are predisposed to certain behaviours as we have 50% of each of our parents genes
strengths of the biological approach
+ favours experiments, contolled enviroment, establish C+E e.g. Casey
+ useful, further understanding of biological factors affecting our behaviour e.g. casey
weaknesses of the biological approach
- reductionist, argues only the biological factors affect our behaviour ignoring social and environmental issues e.g. sperry
- deterministic, shows importance of genes and biology which we cant change or control e.g. Sperry
Blakemoore + cooper A -pps
A = to investigate the development of the primary visual cortex in cats and to find out some properties are innate or learned.
M = lab experiment + IM
PPS = kittens reared in the dark for 2 weeks. They were randomly allocated one of two conditions ( horizontal or vertical , Environment) 2 kittens, one from each condition, were anaesthetised to study neurophysical effects.
Blakemoore + cooper = procedure
- Kittens were reared in the dark from birth
- from 2 weeks they were put in special apparatus for 5 hours per day.
- The kitten stood on a glass platform in a tall cylinder with either horizontal or vertical black and white stripes
- the kitten could not see its on body as it had a collar which restricted visual field.
- this was stopped at 5 months, which is after the critical period. kittens were taken to a well lit room with furniture
- at 7.5 months, two kittens were examined for neurophysiology affects.
Blakemoore + cooper= results
• They were initially extremely visually impaired.
• pupillary reflexes were normal
• no startle response when objects were thrust towards them
• they were frightened when they reached the edge of one surface
• they showed behavioural blindness - kittens raised in a horizontal environment could not detect vertically aligned objects and vice verse.
• kittens raised in a horizontal environment only followed the rods if it was held horizontally and vice verse
Blakemoore + cooper = permanent defects (results)
• They had jerky head movements when following moving objects.
• They would try and touch objects beyond their reach
Blakemoore + cooper = neurophysical affects (results)
• No evidence of severe astigmatism
•Orientation selectivity
Blakemoore + cooper = conclusion
- Visual experiences in the early life of the kitten can modify their brains and have perceptual consequences
- The visual cortex may adjust itself during maturation
- brain development is determined by functional demands upon the brain
- The environment can determine perception at both a behavioural and physiological level.
maguire = a,m,s
A: to show that the hippocampus in the human brain is the structure associated with spatial memory and navigation.
m: quasi-experiment, analysis of MRI scans using VBM and pixel counting. matched pairs
S: 16 taxi drivers, all healthy and right handed. from a selection of 50 non taxi drivers, 16 were selected, being matched on age, sex and health
maguire = pr
the scans of the control group were selected from a data base.
the MRI scans were analysed using VBM ( voxi-based morphometry) and pixel counting, where the cross sections of the anterior, posterior, and body of the hippocampi where compared.
maguire = r
VBM showed no signficant difference between the brains of the 2 groups, but
1. taxi drivers had an increased volume of the posterior hippocampi.
2. the controls had a greater volume of the right anterior hippocampi
pixel counting showed no significant difference.
maguire = c
there are specific structural differences between the hippocampi of London taxi drivers and those who arent.
professional dependence on navigational skills required for taxi drivers is associated with the redistribution of matter in the hippocamus
