Blakemore and Cooper (1970) Flashcards
What is the aim of Blakemore and Cooper’s study?
to investigate the development of the primary visual cortex (in cats) and to find out if orientation selectivity are innate or learned (plasticity)
What is the IV?
horizontal or vertical environment
What is the DV?
visuomotor behaviour:
- startle response
- visual placing
- object detection
- neurophysical behaviour
What is the method?
Lab experiment
What are the strengths of a lab experiment?
- high control over EVs allow standardisation = more reliable
- replicable = more valid and reliable
- causality can be established
What are the weaknesses of a lab experiment?
- lack ecological validity
- lack mundane realism
- artificial
What was the design used?
Independent measures
What are the strengths of independent measures?
- reduced chance of demand characteristics and order effects
What are the weaknesses of independent measures?
- individual differences
- takes more time
- more participants needed
What is the sample?
not stated as to how many cats EXCEPT in part 2: x2 kittens used to study neurophysical effect
What are the weaknesses of the sample?
- small = lack population validity
- ungeneralisable to humans due to structural differences
What are the strengths of the sample?
lots of detailed qualitative data can be gathered
How long were the kittens studied for?
birth - 5 months old
How were the conditions chosen?
random allocation
How did the kittens live for the first two weeks of their life?
housed from birth in a completely dark room
How did the life of the kittens change at two weeks old?
they were put into a special apparatus for an average of 5 hours per day
What was the special apparatus?
- tall cylinder
- clear glass platform (where the kitten stood)
- entire inner surface was covered in high contrast black and white stripes (vertical or horizontal)
- no corners or edges
What did the kittens wear whilst inside the special apparatus?
a wide black collar so their visual field was restricted to 130 degrees (could not see body)
What is important to note about the kittens reaction to the special apparatus?
they did not seem upset by the monotony of their surrounding
Why were the kittens stopped at 5 months old from going into the apparatus?
it was considered past the ‘critical’ period and physiological deficits could have affected observations due to visual deprivation
What was inside the room that the kittens were placed into during phase 2?
furnished with tables and chairs
What had previous research recommended in regards to the development of kittens’ vision?
suggests there is a ‘critical’ period in the development of the visual cortex and if changes occur past the period they are likely to cause irreversible deficits in vision
When was the routine of going into the special apparatus stopped?
5 months old
What did the kittens do after they stopped going into the special apparatus?
they were taken for several hours each week from their dark cage into a small, well-lit room
How old were the 2 kittens in experiment 2?
7.5 months
What was measured from the 2 kittens in experiment 2?
their neurophysiology - listen to the neurons firing
What was the purpose of the room in phase 2?
so their visuomotor behaviour could be observed and recorded
What are 4 controls that were apart of the procedure?
- black collar to restrict vision of anything except IV (stripes)
- same age when going into the cylinder (2 weeks)
- same timings - in cylinder for 5 hours a day
- stopped going in cylinder at 5 months old
What were the key findings as an effect of the special apparatus?
- regardless of IV kittens were initially extremely visually impaired
- showed behavioural blindness:
1) showed no visual placing (not putting paws on the table when about to be put down)
2) guided themselves mainly by touch
3) showed no startle response - in vertical IV they could not detect a rod held horizontally in front of them (unless it made a noise)
What are the key findings after time spent in the room?
- after 10 hours of normal vision they began to show startle response and visual placing
- some deficits were permanent: always followed moving objects with jerky head movements
What data was collected?
qualitative
What are the strengths of this type of data?
lots of detailed reasoning as to the WHY behind behaviour
What are the weaknesses of this type of data?
subjective which makes analysis and comparisons across IVs difficult
What are the key findings of the neurophysiological examination?
- showed no evidence of severe astigmatism
- kittens showed physical blindness - distinct orientation selectivity
- 75% of cells in both cats were binocular
- no obvious large regions of ‘silent cortex’ = suggests that neurons had been respecialised
What are the conclusions that can be drawn from this study?
- visual experiences in the early life of kittens can modify their brains
- a kittens visual cortex may adjust itself during maturation
- brain development is determined by functional demands made upon it rather than preprogramed genetic factors
- the environment determines perception
