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Casey et al - Delayed gratification - Coggle Diagram
Casey et al - Delayed gratification
Background info
Delay gratification -> the ability or act of delaying rewards
Based on Eigsti 2006, a performance on a delay of gratification task in childhood had high predictive validity for later performance on a go/no go task
Go/no go task -> a cognitive task in which ppts are given the instructions to respond in a particular manner to a particular type of stimulus
Aim
Aim 1
To build upon previous research which assessed whether DofG in children predicts impulse control abilities and sensitivity to alluring or social cues (happy faces in this study) at both the behavioural and neural level when ppts were in adulthood
Aim 2
To investigate behaviour at both behavioural and neural levels, and what regions of the brain are active
Aim 3
To investigate sensitivity to alluring or social cues (happy faces)
Method
Longitudinal experiment
Over 40 years
Quasi experiment
Ppts naturally fell into high-delaying or low-delaying groups
IV
High delayer or low delayer
DV
Ex 1
Performance on an impulse control (go/no go task), measured in terms or reaction times and accuracy
Ex 2
Imaging from an fMRI scanner
Sample
562, 4 year olds
Follow up study 1, 155 of the original 562 were studied in their 20s (1993)
Follow up study 2, 135 of the original 562 were studied in their 30s (2003)
From this group, they were identified as above average or below average in
A) Original delay-of-gratification performance at 4 years old
B) Their score on self-control scale in adulthood
This produced a pool of 117 people who were contacted and final 59 agreed to take part in the final part
They were split into 2 groups
1) Those who has above average to DG (high delayers)
2) Those who had below average to DG (low delayers)
32 HD: 20 women, 12 men, mean age - 44.6 years
27 LD: 16 women, 11 men, mean age - 44.3 years
Started in 1960s/70s at Stanford Uni Nursery
Experiment 1
59 (23 males, 36 females) out of 117 who were contacted by Casey et al, they were categorised as HD and LD based on the DofG tasks and self-control measures
Experiment 2
27 (12 males, 14 females) partook in Ex 2 which used an fMRI machine (15 HD, 11 LD)
One man was excluded from the sample for abnormally low performance
Procedure
Experiment 1
Ppts tested who were less able to DG as children and young adults (LD) would, as adults in their 40s, show less impulse control in suppression of a response to 'hot' relative to 'cold' cues
59 ppts consented to take part in a behavioural version of a 'hot' and 'cold' impulse control task
Hot version task
Identical to the 'cold' version except that fearful and happy facial expressions served a s stimuli
The tasks were presented using programmed laptop computers sent to ppts homes
Cold version task
Male and female stimuli where were presented, one sex as a 'Go' stimulus to which ppts were instructed to press a button, and the other sex as a 'No go' stimulus to which ppts were instructed to withhold a button press
Before each run, screen appeared indicating which stimulus category served as the target
Ppts were instructed to respond as quickly and accurately as possible
Each face appeared for 500ms, followed by a 1s inter stimulus interval
A total of 160 trials were presented per run in pseudo-randomised order (120 go, 40 no go)
Experiment 2
fMRI was used to examine neural correlates of DofG
It was anticipated that LD would show diminished activity in the right prefrontal cortex and amplified activity in the ventral striatum compared to HD
Ppts completed a 'hot' version of the go/no go task similar to Ex 1, differences were in timings, number of trials and apparatus
Each face stimulus was presented for 500ms, followed by a jittered inter-trial interval ranging from 2 - 14.5s in duration
In total, imaging data was acquired for 26 no go trials and 70 go trials for each expression
The task was viewable by a rear projection screen and a neuroscreen (a screen which the ppts can view from the fMRI scanner)
A give-button response pad recorded button responses and reaction times
Results
Experiment 1
There was no effect of delay type on the reaction times of the ppts
The ppts all performed with a high level of accuracy for the 'go' trials
Cool - 99.8%
Hot - 99.5%
L and H delayers performed with comparable accuracy on 'go' trials
Accuracy for 'no go' trials was more variable, with LD committing more false alarms than HD
L and H delayers performed comparably on the 'cold' task but the LD trended towards performing more poorly on the 'hot' task than the HD
Only the LD group showed a significant decrement in performance for the 'hot' trials relative to the 'cold' trials
Therefore the go/no go task produced differences between the delay groups only in the presence of emotional 'hot' cures i.e individuals, who as a group, had more difficulty delaying gratification at 4 years of age (LD) showed more difficulty as adults in suppressing responses to happy faces than the HD