casey Flashcards
what was the aim of caseys study
to see if there is a neurological explanation for the ability to delay gratification, and if it’s a set behaviour over time
what was the method
longitudinal study, tracking the participants for 40 years, starting from age 4
2 quasi experiments
IV: ability to delay gratification, operationalized as ‘high delayers’ and ‘low delayers’
who were caseys participants
562 in the preliminary study- from Stanford’s Bing nursery
117 were contacted to take part in the experiments.
59 agreed to do experiment 1
27 down to 26 agreed to do experiment 2
describe the procedure of experiment 1
the sample was divided into 32 high delayers and 27 low delayers
they completed a hot and cool impulse task on pre programmed computers at home- hot was anything that would draw the participant to the stimuli and cool was anything that would direct their attention away
they were given on screen instructions on how to complete the task- press a button (go) or dont press the button (no-go) and were told to complete the task as quickly as possible
the cool task included the presentation of faces- one sex was the go stimulus and the other sex was the no-go stimulus. the expressions on the faces were neutral
the hot task was identical to the cool task except the stimuli was happy and fearful faces rather than neutral.
faces were drawn from the NimStim set of facial expressions
describe experiment 2
sample contained 15 high delayers and 11 low delayers
participants were scanned with an FMRI whilst completing a hot version of the go/no-go task
an electronic response pad was used to record responses to facial stimuli and reaction times
describe the results for experiment 1
both groups were highly accurate in their correct responses to go trials in both hot and cool conditions (99.8% and 99.5%)
low delayers were more likely to respond mistakenly in no-go trials and performed slightly wore than high delayers in the hot version of the task.
low delayers identified at 4 showed greater difficulty suppressing their responses to happy faces than high delayers
decribe the results for experiment 2
there was no significant difference between the two delay groups on reaction times in go trials.
accuracy for both groups was very high for go trials and low delayers had higher false alarm rates in no-go trials (14.5%)
the right inferior frontal gyrus appeared to be critical in withholding responses with low delayers, showing reduced activity in this region during no-go trials.
there were high levels of activity in the basal ganglia (reward related region) for low delayers during the happy no-go trials compared to high delayers
what did casey conclude?
resistance to temptation is a set behaviour over time
cognitive control can be strongly influenced by contextual factors e.g ‘hot’ cues in alluring situations
ventral frontostriatal circuitry supports resistance to temptation- low delayers have a combination of lowered activity in the inferior frontal gyrus and increased activity in the basal ganglia
whats good and bad about the method
good:
- longitudinal design allows the researcher to track development of behaviour in a more reliable way, in this case, casey could see that the ability to delay gratification was a sustained behaviour over time
bad:
-longitudinal design makes research time consuming and often the sample size reduces due to participant attrition. this reduces the usefulness of the conclusions drawn
what’s good and bad about the way data was collected
good:
-high in experimental validity- the FMRI scan is measuring what it claims to be measuring e.g brain activity
-high levels of control enable cause and effect to be determined to a degree
bad:
-lack of control in experiment 1 e.g all participants completed the task at home, how can we be certain they were the ones who completed them
comment on the ethics of the study
good:
-participants (especially in experiment 1 and 2) had the right to withdraw and were fully informed about the purpose of the research
-all identities we kept confidential and materials were not distressing so i adhered to PoP
bad:
-there are negative ethical implications- the participants becoming aware they are low delayers may cause distress (PoP)
-we may question ethics around using children in research who cannot give consent
comment on the validity of the study
good:
-high in experimental validity- the FMRI scanner is measuring what it claims to be measuring
bad:
-the study lacks ecological validity because the participants were reacting to artificial stimuli e.g people respond to emotional cues face to face in everyday situations. a standardised face on a computer screen does not reflect how so body would respond in everyday life
-we can question experimental validity- casey can not be sure whether brain activity causes behaviour, perhaps behaviour changes the brain
comment on the reliability of the study
good:
-the use of standardised procedures enhanced reliability e.g all participants had the same pictures within the conditions and they all had a pre-programmed laptop to control timings etc. they also all had the same FMRI scan in experiment 2 which scanned all the participants brains in the same way
bad:
-the lack of control when the participants were at home in experiment 1 makes us question the standardisation of the environment so consequently the reliability
-the lack of the brain scan at age 4 makes us question the reliability of the findings
comment on the sampling and the sample
good:
-the use of opportunity sampling was convenient and allowed a large sample size to be obtained, improving the ability to make generalisations
-both male and females were used (no gender bias)
-self selected sampling is more ethical
bad:
-the use of self selected sampling for experiments 1 and 2reduced the sample size which inhibited the ability to make generalisations
-the use of a restricted sample e.g only 26 participants who wee all american reduces generalisability as well as being ethnocentric
