IB Psychology HL - BLOA - Discuss use of tech in Investigating the Link Between Biological Factors and Behaviour

• non invasive procedures

- used to measure brain activity, look at brain structures, and discover the functions of brain areas

positron emission tomography

• injects radioactive sugar that produces gamma rays while it’s being metabolised by the brain

• based on the principle that rate of metabolism depends on activity

strengths:

• can show dynamic info in real-time

• helpful diagnostic tool showing abnormalities in activity levels

limitations:

• not very precise

• some health concerns

• but overall quite safe

PET study: Raine et al. (1997)

To investigate brain abnormalities in murderers using PET scans

1. 41 prisoners charged with murder were paired with a control (non-murdering) subject

2. Each control subject had the same age, sex, and absence/presence of schizophrenia as their partner

murderers exhibited:

• lower activity in the prefrontal cortex (linked to a loss of self-control and altered emotion)

• lower activity in the corpus callosum (connects the two brain hemispheres), suggesting less communication between the 2 hemispheres

• lower activity than with controls in the amygdala (linked to emotional expression)

• lower activity in the angular gyrus (linked with verbal ability and educational success)

problems with the mentioned structures may cause a lack of inhibition for violent behaviour and greater fearlessness

• gender imbalance (only 2 out of the 41 participants were female)

• matched-pairs design was a real strength as it ruled out other effects on brain activity

• but findings apply only to a sub-group of violent offenders (not to other types of violence or crime)

• some participants were murderers while others were manslaughterers (specific brain abnormalities should not be generalized)

• however the PET scan can lack precision

• combines computer and X-ray technology

• X-rays show human bones but not soft tissue

• computer technology fills in to allow us to see those tissues

• CT scans can be taken from the top, bottom, back, front or sides of the head and can show the brain at any depth

• basically cross-sections of the brain

strengths:
- extremely useful for showing structural changes (e.g. due to a brain tumour or brain damage

limitations:

• can only produce structural images

• cannot show brain activity

• health concerns due to x-rays

CT study: Ogden (2005)

cause: damage to one side of the brain
effect: inattention to the opposite side of space

investigate hemineglect’s biological causes and cognitive effects

• CT scan showed that Janet had a tumour in the parietal lobe in her right hemisphere

• she ignores everything on the left side of space

• often justifies, rationalizes and jokes about her tendencies

the fact that Janet appears to be aware of her condition implies that her condition doesn’t cause inability to sense the left side of space, simply a willing neglect

• yields rich data and detailed data

- can be very useful for constructing/challenging theories

• extent of generalizability to population is limited

- ethical considerations: participant may be upset by invasiveness

• effective in showing correlations between specific brain areas and behaviour

• but takes a reductionist approach to complex issues

• brain differences in the murderers (Raine et al., 1997) may have been a consequence of a violent lifestyle and not its cause

• the smaller hippocampi (Luby, 2012) may have been the result of lifestyle factors such as poor diet or biological factors such as inheritance

• main idea: use of PET and MRI to investigate the link between brain functions and behaviour

for each tech:

• explain how it shows brain processes in action

• how does it help us understand how the brain works?

• evaluate their use (ethical, methodological)

• evaluate the studies mentioned

• state advantages and disadvantages + give your opinion on whether advantages outweigh disadvantages + explain why

PET: Raine et al. (1997)
MRI: Ogden (2005)