Biological Psychology in Sec A Flashcards
What is the assumption, focus, the theme and the studies in biological psychology?
Assumption: our biological makeup affects our behaviour, many behaviours have a psychological cause which may be genetically or environmentally altered
Focus: psychologists should study brain, nervous system, and other biological systems acting on brain to explain behaviour
Theme: REGIONS OF THE BRAIN
- classic study: Sperry (1968)
- contemporary study: Casey et al (2011)
Describe the context and background of Sperry.
- research to explore localisation of function
- localisation: extent to which particular jobs are performed by particular parts of brain
- so,e functions demonstrate lateralisation
- lateralisation: difference between roles of left and right hemispheres of brain, so is the specialisation of diff brain hemispheres
- contralateral control: movement of one side of body is controlled by opposite side of brain
- corpus collosum: joins left and right side of brain and exchanges info and messages across brain
- studies particular focus explores when two hemispheres are split (hemispheric separation)
- corpus collosum is therefore cut which prevents cross talk and communication of two hemispheres.
Describe the aim of Sperry.
- to test effects of hemisphere disconnection in humans
- specifically to investigate whether cognition, including perception and memory, differs between hemispheres, and extent to which hemispheres would normally interact to achieve these functions
Describe the method of Sperry in terms of design.
- research method was a quasi experiment
- done in a lab environment with control over specific variables
- IV: fact they had split brains
- DV: measuring effect on individuals performance in tests of cognition
Describe the method of Sperry in terms of participants.
- 11 split brain patients = at least one woman
- all had history of advanced, severe epilepsy that could not be controlled by medication
- all had sever epilepsy for at least ten years
Describe the method of Sperry in terms of procedure.
- quasi experimental method involved comparing performance of pps on tasks with performance of people who had not undergone hemisphere disconnection, to investigate localisation of brain function
- study was also a case study method, so an in depth investigation of the 11 pps
- specialised equipment used and were highly standardised
- all tasks involved asking pps to respond to visual information with one eye blindfolded and using other to fixate on a point in middle of screen
- stimulus then projected on either left or right side of fixation point for less than a tenth of a sec
- such short time of showing stimulus to ensure pp did not have time for eye movement as this would pass info across both sides of visual field and so both brain hemispheres
- language only processed in left hemi of brain, so when stimulus presented to left visual filed of split brain patients, they should not be able to name stimulus as right hemi controls left visual field and vice versa
- another task involved asking pps to respond to tactile info: presented with stimulus to one hand so could not see it, then asked to name it, if stimulus presented to left hand then should not be able to name it as left hand goes to right hemi which does not control language
- also possible to present auditory (sound) and olfactory (smell) stimuli to one side of brain by blocking unused ear / nostril
Describe the results of Sperry.
- when pps presented with an image in one half of visual field, and then present with same image in other, they responded as if had never seen image before
- if same image presented in original field again, were able to recognise image
- not able to give description of an image presented in left hand side of visual field, either not noticed or appeared as a flash
- although, could respond verbally by pointing with left hand to a matching picture or selecting one object among others - only works with right handed pps tho as means info goes to left hemi which controls language
- if two symbols presented simultaneously, one in each visual field, and pps asked to draw what they saw with their left hand, they would only draw left visual fields pic as left hand controlled by right hemi which controls only left visual field aswell
- when required to then say what they had just drawn, pp would name object from right visual field, not object they drew, as lang comes from left hemi which controls right field so they’d say name of that image
- objects put in hand for identification by touch could be named if in right hand, but only completely guessed if in left hand or were unaware anything was in hand at all
- if object taken from left hand and placed in ‘grab bag’ among other items, pp able to retrieve with left hand and identify it
- Sperry found hemisphere disconnection did not affect pps intelligence (measured by IQ test) or personality
- worth noting patients are only affected from surgery compared normal pps when tasks set up to show Info through diff visual fields and parts of body to send to only one side of brain, but would not be affected in everyday lives as use all fields and limbs.
Describe the conclusions of Sperry.
- argued that his studies give considerable support to argument of lateralisation of function: that diff areas of brain specialise on diff tasks e.g. Left for language
- also argued that each hemisphere of the brain has its own perceptions, memories and experiences.
Evaluate the research method of Sperry.
- was a lab ‘experiment’, but a lab procedure as only some parts were truly experimental
- many comparisons were to non split brain people, although they weren’t part of sample included
- a control group of non-split brain epileptics would have provided better comparison
Evaluate the data on Sperry.
- depth and detail of data collected was a strength of study as is both quantitative and qualitative so has strengths of both types of data
- having both types is useful for interpreting findings e.g. Qualitative data supporting tests help to show that understanding of effects of hemisphere disconnection is correct.
Evaluate the ethical considerations of Sperry.
- although were ethical issues involved in surgery itself, these are not issues with sperrys research
- understanding reasons for mental tiredness, and discovering there are ways in which split brain patients outcompete normal people may slightly helped patients make progress
Evaluate the validity of Sperry.
- took place in highly controlled environment so possible to eliminate extraneous variables and be confident IVs being tested are those affecting DV
- stimuli only being displayed for short time ensured not possible to glance away from fixation point and view stimulus through other eye
- potential weakness with lab studies is lack of realism of environment and pps tasks, I.e. Low ecological validities because findings may not generalise beyond lab setting, difficult to set up lab procedures where people behave completely natural
- study was concerned w discovering problems rather than helping in real world, but Sperry did note that in day-to-day life split brain patients have little impairment
Evaluate the reliability of Sperry.
- reliability = consistency
- is reliable if can be precisely replicated + obtains same results consistently
- lab experiments = easy to replicate, and sperrys has been
- but, further evidence of some language ability in right hemi presents some concern, as damage to left hemi can cause compensation to have some reorganisation of Lang ability in right hemi
- this would make epileptic sample unrepresentative, this pattern seen in brain scanning studies (e.g. Thompson 2000)
Evaluate the ethnocentrism of Sperry.
- are some diffs in lateralisation between people using diff languages
- so for e.g. If some cultures were less lateralised in speech function, individuals from these cultures who undergo split brain ops would produce diff results
- this suggests sperrys results may only apply to cultures sharing same lateralisation patterns as English speakers
- so low generalisability and ethnocentrism.
Evaluate the sampling bias of Sperry.
- 11 sound like small sample, but is impressive due to rarity of patients and depth of their study
- all sufferers of epilepsy so is a restricted sample, so generalisation to whole pop may be invalid
- extent of disconnection varied between patients, presenting individual diffs in results
- no of both men and women used is not known, and there are gender diffs in lateralisation of function (e.g. In language) so this important in terms of generalisability.