C2: Biological Psychology Flashcards
Sperry: aim
To investigate the effects of hemisphere deconnection and to further understand the functions of the left and right hemispheres
Sperry: method
Quasi experiment, or a series of case studies
Sperry: independent variable
Presence of absence of a split brain
Sperry: dependent variable
Whether the participant could name objects, recognise objects and draw objects
Sperry: participants
Split brain participants were 11 patients (male and female) who had already had the split brain operation to disconnect the two hemispheres. All of these have a severe history of sever epilepsy which had not responded to drug therapy
Sperry: visual test procedure
- Show one or both visual field a stimulus
- When presented to one eye, the other stays covered and to focus on a fixation point, information flashed fro 1/10th of a second
- Similarly when image is presented to both visual fields, focus on a fixation point and image is flashed for 1/10th of a second
Sperry: tactile test procedure
- Participants could not see their hands or the objects that they had been given to hold
Sperry: visual tactile test
- Both sight and touch
- Image presented to left or right visual field and participant would have to try and find the object from an array using their left or right hand
Sperry: test of the right hemisphere procedure
- Array of geometric shapes are presented to both visual fields
- In the middle, a nude picture flashes to the left visual field only, so seen by the right hemisphere
- Participant is later asked fi they had seen anything other than geometric shapes
Sperry: conclusion
Concluded in most patients the dominant hemisphere is the left hemisphere due to language skills which are based in the left hemisphere controlling words and ability to speak. He also concluded a severing of the corpus callosum stops the two hemispheres from communicating with one another
Casey: aim
To build on previous research to assess whether delay of gratification in childhood predicts impulse and self-control abilities at the behavioural and neural level in adulthood
Casey: research method
Quasi experiment, longitudinal
Casey: independent variable
Whether the participant was a high or low delayer
Casey: dependent variable for experiment 1
Was the participants performance on the impulse control task in terms of reaction times and accuracy.
Casey: dependent variable for experiment 2
Same as experiment 1, but researchers also examined the brain scan results from the fMRI
Casey: experimental design
Independent and repeated measured
Casey: participants
562 children aged 4 years old took part,
1993 aged 20= 155 of the original sample completed self-report measures of self control
2003 aged 30= 135 of original participants
2011 aged 40= 117 of 135
Casey: umber of high and low delayers in 2011
High delayers- 60
Low delayers- 57
Casey: experiment one number of high and low delayers
High delayers- 32 (12 male, 20 female)
Low delayers- 27 (11 male, 16 female)
Casey: experiment two number of high and low delayers
High delayers- 15 (5 males, 10 females)
Low delayers - 11 (7 male, 4 female)
Casey: experiment one procedure
- Participants sent laptops to home using Inquisit Software to present experimental tasks
- Participants were required to complete two types of go/no go tasks
- Reaction times measured as well as accuracy
- Two versions of this are the hot and cold condition
- Before each run, a screen appeared on the laptop indicating which stimulus category served as a target, asked to respond quickly
- Each face appeared for 500ms followed by a 1 second interval, total of 160 trials
Casey: experiment one reaction time results
There were no effects of delay group on reaction time measures to correct ‘go’ trials. This means that it didn’t matter if you were a high or low delayer when correctly pressing the button during the ‘go’ trials
Casey: experiment two procedure
- Participants scanned with a General Electric Signa 3.0-T fMRI scanner with an 8 channel head coil
- E prime analysis used to display the tasks to the participants by a rear projection screen and button responses and reactions times were recorded on a Neuroscan five-button respond pad that the participants used
- Participants completed a ‘hot’ version of the go/no go task similar to that of experiment one but had a difference in timing, apparatus and the number of trials
Casey: experiment two reaction time results
The two delay groups (high/low) did not differ significantly in reaction times in correct ‘go’ trials. This is similar to the reaction time results in experiment 1
Casey: experiment two accuracy results
Overall, accuracy rates for the ‘hot’ go/no go task were uniformly high for ‘go’ trials with more variable performance to ‘no-go’ trials (mean= 98.2% correct hits and 12.4% false alarm rate)
Casey: experiment two imaging results
The ‘no-go’ trials identified candidate regions of the brain differently engaged as a function of cognitive control tasks (they saw different brain areas involved in the delay of gratification tasks)
Casey: what is the role of the right inferior frontal gyrus for?
Involved in accurately withholding a response and compared wit high delayers, ow delayers had diminished recruitment (less activity) of the inferior frontal gyrus for correct ‘no-go’ trials relative to go trials. This supports the idea that low delayers would have less activity here as they were not very good at withholding their responses in ‘hot tasks’
Casey: what is the role of the ventral striatum?
Shows a significant difference in recruitment between high and low delayer. This reward related region of the brain showed a three way interaction of group x trial x emotion, with elevated activity to happy ‘go’ trials for low delayers relative to high delayers
Casey: conclusions
- Delay of gratification will continue to show reduced self-control abilities, have more difficulty as adults in suppressing responses to positive social cues than those who do not.
- Sensitivity to environmental hot cues plays a significant role in an individual’s ability to suppress actions towards alluring cues
Blakemore and Cooper: aim
To investigate the development of the primary visual cortex (vision area of the brain) in cats and to find out if some of it’s properties such as orientation selectivity are innate or learnt
Blakemore and Cooper: research method
Lab experiment
Blakemore and Cooper: independent variable
Whether or not the kittens were reared in a horizontal or vertical environment
Blakemore and Cooper: dependant variable
The kittens visuomotor behaviour (how hey moved in relation to what they could see) once they were placed in an illuminated environment
Blakemore and Cooper: experimental design
Independent measures
Blakemore and Cooper: sample
Kittens studied from birth were randomly allocated to one of two conditions were used to study neurophysical effects. The kittens were all housed in complete darkness until they were 2 weeks old
Blakemore and Cooper: procedure
- From 2 weeks old, put into special apparatus for an average of 5 hours per day
- Kitten stood on clear glass platform inside a tall cylinder, the entire inner surface was covered in striped
- Kitten wore a black collar that restricted its visual field ti a width of 130 degrees
- This was repeated until kittens were 5 months and the they were beyond the critical period in which visual deprivation causes physiological deficits
- Kittens then taken for several hours each week from their dark cage to a small, well lit room where their visual reactions were observed and recorded
- At 7.5 months, two of the kittens were anaesthetised so that their neurophysiology could be examined
Blakemore and Cooper: qualitative results
- Guided themselves mainly by touch
- Frightened when reached the edge of the table they were standing on
- Showed no startle response when an object was thrust towards him
- Showed ‘behavioural blindness’ in that kittens raised in the horizontal condition could not detect vertically aligned objects vice versa
Blakemore and Cooper: permanent defects
They followed moving objects with clumsy, jerky head movements, they often tried to touch things well beyond their reach
Blakemore and Cooper: conclusions
- The environment can determine perception at both a behavioural and physiological level
- Visual experiences in the early life of kittens can modify their brains and have profound perceptual consequences
Maguire: aim
To demonstrate that the hippocampus is the region of the brain associated with spatial memory and navigation
Maguire: research method
Quasi experiment, correlational anyalysis
Maguire: experimental design
Independent measures
Maguire: taxi driver participants
16 right handed male London taxi drivers aged 32-62 (mean=44) who had been licensed London taxi drivers for at least 11/2 years, with the average time being spent ‘On the Knowledge’ of 2 years. All had healthy, general medical, neurological and physiological profiles
Maguire: control group participants
50 right handed males aged 32-62 who had been scanned for the MRI database at the Wellcome Department of Cognitive Neurology. They were elected so no one with health problems were included.
Maguire: what is VBM
An objective and automatic procedure that identifies regional differences in grey matter density in MRI scans. It would show in 3D where there were different densities of grey matter in the brain
Maguire: what is pixel counting
A 2D measurement of volume, it is possible to calculate differences by pixel counting ‘slices’ of the scan. The scan separated into 26 slices and 24 of these focused on the hippocampus
Maguire: pixel counting in terms of taxi drivers
This was carried out on scans of the taxi drivers and 16 age matched controls taken from 50. Pixel counting was carried out by one person experienced in the technique and blind participants identity as taxi drivers or controls and the outcome of the VBM analysis
Maguire: procedure
1) Structural MRI scans were obtained from both taxi drivers and non taxi drivers
2) Two image analysis methods were used to analyse the data (pixel counting and VBM)
3) Comparisons were then made between the findings from the scans of the taxi drivers and those of non taxi drivers.
Maguire: controls
- Male
- Right handed
- Non taxi drivers and taxi drivers were age matched and scanned at the same unit
- Pixel counters blind to the VBM results and whether the scans were of a taxi or non taxi driver
Maguire: VBM analysis results
- In the taxi drivers the increased grey matter volume was found in the right and left posterior hippocampus whereas in the non taxi drivers, there was relatively more grey matter volume in the right and left anterior hippocampi
- No differences were observed elsewhere in the brain
Maguire: anterior hippocampus
Non taxi drivers had greater anterior right hippocampal volume than the taxi drivers
Maguire: posterior hippocampus
Taxi drivers had a great posterior hippocampal volume than the non taxi drivers
Maguire: correlational analysis
- The authors carried out a correlational analysis to see if there was a correlation between hippocampal volume and time spent as a taxi driver
- There was a positive correlation found between time as a taxi driver and volume of the right posterior hippocampus
- The length of time spent as a taxi driver correlated negatively with the volume of the anterior hippocampus
Maguire: summary of findings
1) Taxi drivers had a significantly greater volume of grey matter in the posterior hippocampus, whereas the control group had a greater volume in the anterior hippocampus
2) There was a correlation between the amount of time taxi driving and volume of grey matter in the posterior and anterior hippocampus
Maguire: conclusions
- The brain changed in response to the demands of being a taxi driver, rather than the idea that people choose to be a taxi driver because they have a pre existing brain difference
- Human brain has plasticity, the ability to change to meet demands of the environment
