Casey 2011
Keywords
High delayers: Individuals who were able to delay their gratification
Low delayers: Individuals who were not able to delay their gratification
Hot cue: Factors that are appealing
Cool cue: Factors that are not appealing
Delay of gratification: An ability to put off something fun/pleasurable now in order to wait for something that is greatly fun/pleasurable or rewarding later
Cognitive control: Ability to suppress inappropriate thoughts or actions in favour of appropriate ones
Localisation of function: Different areas of the brain are associated with particular physical and psychological functions
Background
Metcalfe and Mischel (1999) suggested that cool and hot cues involved different areas of the brain. Cool cues: Inferior frontal gyrus/pre-frontal cortex. Hot cues: Ventral striatum/basul ganglia neural circuit
Marshmallow test (1960s) showed some children could delay their gratification and wait and get another marshmallow, but some could not delay their gratification and ate the first marshmallow
Sample
562 pupils from Stanford Nursery School took part in the marshmallow test
155 completed a self control scale in their 20s
135 completed a self control scale in their 30s
117 contacted due to their above/below average scores in the marshmallow test AND the self control scales (60 low delayers, 57 high delayers)
59 took part in experiment 1 (32 high delayers (12 males, 20 females) and 27 low delayers (11 males and 16 females))
27 took part in experiment 2 but one was removed for poor fMRI performance (15 high delayers (5 males and 10 females) and 11 low delayers (7 males and 4 females))
Method
Experiment 1
Instructed to press a button/not press a button to a certain gender presented on the screen
Read on screen instructions and were told to act as quickly as possible
Each face shown for 500 milliseconds
1 second interval between each face
Tasks presented using programmed laptop computers that were sent to the participants' homes (measuring accuracy and reaction times)
Longitudinal study (Age 4-40)
Quasi experiment
Experiment 2
Used participants from experiment 1
Aimed to show that low delayers would show less activity in their pre frontal lobe cortex (inferior frontal gyrus)
Participants scanned in an F-MRI scanner while completing the go/no go task
Each face was presented for 500 milliseconds
Intervals between races ranged from 2-14.5 seconds
160 trials were presented in a randomised order (120 go, 40 no-go)
IV: High delayers or low delayers
DV: Impulse control on the go/no-go task, brain activity in the inferior frontal gyrus and ventral striatum
Results
No difference in reaction times
Both groups accurate to 'go' trials in both the cool and hot tasks, but low delayers made more errors in their responses to the 'no-go' trials
Individuals who showed more difficulty delaying their gratification in childhood showed difficulty in adulthood in suppressing responses/cognitive control
Low delayers showed more activity in the ventral striatum and less activity in the inferior frontal gyrus.
Inferior frontal gyrus is responsible for cognitive control
Ventral striatum is responsible for hot cues
48 trials presented (35 go, 13 no go)
Evaluation
Aim: To investigate the extent to which the ability to resist temptation at pre-school age affected the same participants in adulthood. Control over impulses and sensitivity to social cues at the behavioural and neural level were examined.
Psychology as a science: fMRI scanner used, collected quantitative data, but no manipulation of IVs and collected qualitative data
Usefulness: Teaching children to wait improves cognitive control, teach cooling strategies
Nature/Individual explanations: Does not look at environmental causes behind the ability to delay gratification, just brain activity
Socially sensitive research: Questions whether people can really be blamed for not controlling impulses
Ethical considerations: Informed consent, confidential, no harm to participants
Validity: Quasi (ecological), males and females (population), standardised (internal), but experiment 1 was carried out at participants' homes (internal) and no manipulation of IVs (internal)
Ethnocentric: All originally from Stanford
Reliability: Standardised timings, quantitative data, fMRI scanner, but collected qualitative data, and is not entirely replicable as experiment 1 was carried out at home
Sampling bias: Males and females, but all went to Stanford Nursery School