Core study ten- Blakemore and Copper (Biological area) Flashcards
Background
Blakemore & Cooper were interested in investigating brain plasticity.
Brain plasticity - your brain adapts and changes according to what you do in your life.
Blakemore & Cooper were inspired by the work of Hirsch & Spinelli. They were interested in neurons in the visual cortex of the brain.
They found they could change the way the neurons in the visual cortex aligned themselves by controlling what kittens could see as they grew up.
Kittens were raised could only see vertical stripes in one eye and horizontal stripes in the other eye.
When the cats were then released into an everyday environment, the researchers found that they had visual impairments.
Visual cortex
the part of the brain that receives and processes sensory nerve impulses from the eyes
Startle response
The ‘backing off’ reaction of a cat when an object is moved quickly towards their face
Visual placing
When a cat puts its feet out to meet the edge of a surface
Overall aims
The aim was to investigate how being raised in a visually restrictive environment would affect the visual brain development of cats.
- Compare the behavioural consequences of raising kittens seeing only horizontal or vertical stripes.
- Investigate the neurophysiological effect on neurons in kittens’ visual cortex (brain plasticity)
Sample
2 kittens from birth until approximately 1 year of age.
Procedure
The first two weeks- The newborn kittens were kept in a completely dark room for the first 2 weeks of their life
2 weeks to 5 months- From the age of two weeks, the kittens were placed in a cylinder for 5 hours a day (and returned to the
darkened room for the rest of the day). The cylinders were 2m high and about 46cm in diameter. The
cylinders were made up of a series of black and white vertical or horizontal stripes of varying widths, with each kitten being placed in one of these environments.
At 5 months- The kitten was taken into a well lit room with furniture to be test their behaviour
Controls of the experiment
The kittens had identical visual environments, apart from the lines being vertical or horizontal.
The cylinders were the same size
The kittens spent the same length of time in the cylinders
They both wore a collar
They could move about freely in the cylinder
They were kept in the dark when not in the cylinder
Research method
Lab Experiment
IV
The Independent Variable was the orientation of the stripes within the cylinder (either horizontal or vertical)
Experimental design
As each kitten was exposed to a different striped cylinder the experimental design was independent measures
Behavioral results
The cats initially showed visual deficits when taken into the well lit room
They navigated around the room by touch
They were generally clumsy
They had normal pupillary reflexes
They had no startle response
They had no visual placing
After ten hours of exposure of the well-lit surroundings-what changed and what deficits did the kittens still show.
Deficits they quickly recovered from:
Visual placing
Startle response
Jump easily from chair to floor
Deficits that remained:
There tracking of visual objects was clumsy, jerky head movements and they often tried to reach for objects moving across the room and way out of their reach. They often bumped into things.
How did the vertical and horizontal cats differ
The cats were virtually blind to objects which were in the opposite orientation to the environment they were exposed to (i.e. the kitten raised in the vertically striped cylinder could not see horizontal lines and vice versa).
A sheet of perspex glass with thick black and white lines was held in front of them. If presented to them in the wrong orientation (e.g. vertically for the horizontally raised kitten), they would not respond but would show fear when held in the correct orientation.
A rod was shaken in front of them. The kittens would try to follow and chase the rod but only when it was held in the same orientation as the environment the kitten had been exposed to
Neurophysiological Findings
Results from the scans showed that the visual neurons within the visual cortex had aligned themselves to match the environment the kitten was brought up in. There were little to no neurons aligned to the opposite direction (For example the cat brought up within the horizontal cylinder had neurons aligned within a horizontal arrangement).
This is because the cats had no need for neurons in the other direction and therefore these were moved elsewhere.
Types of data
Behavioural- Qualitative descriptions of the deficits shown by the cats in the well lit room
Neurophysiological- Quantitative data based on the alignment of the visual neurons from the visual cortex scan
Conclusions
The difference between the kittens suggests that neurons can change their preferred orientation according to the stimulation they receive, matching the ability of the brain to respond to the features in its visual input.
Ethics
Defendant
Replacement:
The use of animals was necessary as the research was conducted in the 1970s and so there were no real alternatives to studying animals in the study. Kittens were chosen as they had very similar visual cortices to humans.
Reduction:
The researchers minimised the number of animals needed by only testing the impact of this early visual exposure on two kittens (one in each environment)
Refinement:
The procedure was followed to try and minimise the harm caused to the kittens: for example,
they were placed under anaesthetic and paralysed while their individual neurons were studied in order to reduce the risk of brain damage while this measure was taken
Criticized:
The benefits of the findings to humans is questionable as we don’t know if human brains would
show the same kind of plasticity as that of kittens. Also, it is difficult to see what the practical applications of the findings actually are. The animals did also show some long-term visual deficits so they were not completely protected from harm.
Ethnocentrism
Not particularly relevant here. We are looking at biological factors and the environment the kittens were in were not culturally biased.
Reliability
Internal-The procedure was highly standardised and replicable due to the high level of controls
External-Only 2 kittens were used in this study but perhaps this doesn’t matter as we are investigating biological concepts
Validity
Internal-Seemed to be a good test of brain plasticity as the only difference in the procedure for the kittens was the direction of the stripes.
Population-Possible problem with generalising beyond the species of kittens
Concurrent-The researchers tested the impact of the restricted visual environment on both the behaviour and neurophysiology (brain structure and function) of the kittens. Both these measures showed the same thing - that the kittens were blind to the opposite orientation of visual information
Ecological-Not a realistic scenario as the environment was so visually restricted. This doesn’t happen in real life.
Links to Debates
The study supports nurture as it suggests that the environment that kittens were exposed to changed their brain physiology.
This was a reductionist piece of research as it investigated the impact of a single variable (vertical or horizontal stripes) on the kittens behaviour and physiology using highly controlled procedures
The research was carried out in a scientific way as the procedure contained a lot of controls to make it standardised and the findings were fairly objective - especially with regards to the neurophysiological measures.
Principle of Biological area
Our behaviour is explained by biological processes
Psychology should study biological systems to determine the cause of our behaviour
Concepts of biological area
Use of scientific equipment (e.g MRI)
Brain plasticity
How does Blakemore and Copper link to the biological area
Investigated how the visual cortex can be changed by giving kittens a restricted visual environment
Strengths of the biological area
Often high in internal reliability due to the tightly controlled lab conditions
We can establish cause and effect by having tightly controlled lab conditions
Weaknesses of the biological area
Can lack ecological validity as often uses lab experiments
Is often reductionist by only investigating biological causes of behaviour
