Casey et al Flashcards
Background
Eigsti (2006) showed performance on a delay of gratification task in childhood had high predictive validity for later performance on a go/no go task.
Alluring or social contexts can diminish self-control
The marshmallow test is an experimental design that measures a child’s ability to delay gratification. The child is given the option of waiting a bit to get their favourite treat, or if not waiting for it, receiving a less-desired treat
Theory/ies on which the study is based
The ability to resist temptation in favour of long-term goals is an essential part of individual, societal and economic success.
Alluring situations can diminish control.
Delay of gratification depends importantly on cognitive control. Individuals use different cognitive strategies to delay gratification and there appear to be naturally existing differences in the spontaneous use of these strategies
A correlation had been found between an avoidance of risky behaviour and greater excitation in the right inferior frontal gyrus.
The ventral striatum balances motivation
What experimental method was used?
Quasi (whether the P was a low delayer or high delayer could not be manipulated)
Was this a snapshot or longitudinal study?
Longitudinal study - followed original participants from the age of four years until they were in their 40s
What experimental design was used?
Repeated measures design
Participants completed seed-control scales when in their 20s, 30s and that those taking part in EXP 1 did both the ‘hot’ and ‘cool’ go/no-go tasks means the study is RMD
What was the IV?
The IV was whether the participant was a high delayer, or a low delayer
naturally occurring and could not be manipulated
DV?
DV was the performance on the impulse control task (in terms of reaction times and accuracy) in EXP 1 and the performance on the impulse control task (in terms of reaction times and accuracy) and imaging results using fMRI.
Sample
- 562, 4 year olds from Stanford’s Bing nursery School completed a delay of gratification task during the late 1960s.
- 59 (23 M, 36 F) of 117 agreed to take part in this longitudinal behavioural study (EXP 1).
- Participants were classified as low or high delayers from the results of their delay of gratification performance and the self-control measures.
EXP 1:
• 32 high delayers and 27 low delayers
EXP 2:
- 27 agreed to be part of a functional neuroimaging study.
- 15 HD, 11 LD
- One person excluded so only 26 in exp 2
Procedure of experiment 1
- This tested whether individuals who were less able to delay gratification 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 ‘cool’ cues.
- The 59 participants consented to take part in a behavioural version of a ‘hot’ and ‘cool’ impulse control task
- Participants completed 2 versions of the go/no-go task.
The cool version consisted of male and female stimuli which were presented, one sex as a ‘go’ (target) stimulus to which participants were instructed to press a button, and the other sex as a ‘no-go’ (non target) stimulus - participants told to not press the button
the hot version of the go/no go task was identical to the cool version except that fearful and happy facial expressions served as stimuli.
Procedure of experiment 1
- Before the onset of each run, a screen appeared showing which stimulus category served as the target
- Participants were instructed to respond as quickly and accurately as possible.
- Each face appeared for 500ms, followed by a 1s interstimulus interval
- A total of 160 trials were presented per run in pseudo randomised order (120 go, 40 no go)
- The task was therefore a 2 (trial type go, no-go) x 2 (stimulus sex: male, female) factorial design
- Accuracy and response latency data (reaction times) were acquired in four runs representing each combination of stimulus sex (m, f) and trial type (go, no-go)
- The tasks were presented using programmed laptop computers sent to participants’ homes.
Procedure of experiment 2
- fMRI was used to examine rural correlates of delay of gratification. it was expected that low delayers would show diminished activity in the right prefrontal cortex and amplified activity in the ventral striatum compared to high delayers.
- Participants completed a ‘hot’ version of the go/no-go task like that used in experiment 1. Differences were in timing, number of trial and apparatus.
- Each face stimulus was presented for 500ms, followed by a jittered interval interval ranging from 2 to 14.5s in duration (mean 5.2s)
- A total of 48 trials were presented per run in pseudo randomised order (35 go, 13 no-go)
- in total, imaging data were 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 five-button response pad recorded button responses and reaction times.
Procedure of experiment 2 (2)
- One participant was excluded for excessively poor behavioural performance on the fMRI version of the task leaving 26 participants
- A 2 x 2 x 2 group linear mixed-effects model was conducted with factors of trial type (with subjects: go, no-go), emotion (within subjects: happy, fearful) and group (between subjects: high delayer, low delayer).
Key findings in experiment 1
• Reaction time
There were no effects of delay group on reaction time measures to correct ‘go’ trials
• Accuracy
Participants performed with a high level of accuracy for correctly responding to ‘go’ trials during both the ‘cool’ (99.8% correct) and ‘hot’ tasks (99.5% correct)
Low and high delayers performed with comparable accuracy on ‘go’ trials. Accuracy for no go trials was more variable, with low delayers committing more false alarms than high delayers
Low and high delayers performed comparably on the cool task but the LD trended toward 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 cool trials
Overall, the go/no-go task produced differences between the delay groups only in the presence of emotional hot cues. Individuals who 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
Key findings in experiment 2 (1)
• Reaction times
The two delay groups did not differ significantly in reaction times in correct ‘go’ trials
• Accuracy (inside the scanner)
Overall accuracy rates for the ‘hot’ go/no go accuracy were consistent with the observed differences in the ‘hot’ task performance
In experiment 1, with the LD committing more false alarms than high delayers
Key findings in experiment 2 (2)
- Imaging results
- The no go vs go trials found candidate regions of the brain differentially engaged as a function of cognitive control tasks.
- The right inferior frontal gyrus was involved in accurately withholding a response.
- Compared with HD, LD had diminished recruitment of the inferior frontal gyrus for correct no-go relative to go trials.
- The ventral striatum showed significant difference in recruitment between HD and LD
- This reward-related region of the brain showed a 3 way interaction of group x trial x emotion, with elevated activity to happy ‘no go’ trials for LD compared to HD
- These results showed that the prefrontal cortex differentiated between no go and go trials to a greater extent in HD. The VS showed exaggerated recruitment in LD
