Casey Et Al (2011) - Delayed Gratification

• delayed gratification ; 1

  → mischel demonstrated how some children could resist temptation and others could not

  → he tested this by putting a marshmellow in front of a pre-school child in a lab and told the child he had to go out. they were told they could have the marshmellow but if they waited ,, upon his return they would get two. he left for 15 minutes.

  → the ability to resist temptation depends on cognitive control (some have better self-control than others)
• delayed gratification ; 2

  → those that could wait were more likely to naturally focus on 'cool' aspects such as the shape or colour of the marshmellow ,, whereas those that couldn't resist focus on 'hot' aspects such as the smell and taste

  → children can be taught 'cooling strategies' such as to think of the marshmellow as a cotton wool ball ,, which can make them resist temptation for longer

  • cool cues are easier to resist than hot cues

  → high delayer - can wait and receive reward

  → low delayer - can't wait at all
• testing adults - go/no-go tests

  → 'alluring stimulus' changes with age... a marshmellow is not as interesting to an adult as it is to a 4 years old

  → go/no go tasks can be used to test cognitive self-control in adults. here participants have to press a button when given a 'go' instruction & refrain from pressing it (which requires cognitive control) on a no-go instruction

  • E.G. - the target photograph is a female face. participants have to press a button if they see another female (go) and avoid pressing the button if they see a male (no-go)
• brain regions

  → there are two interacting neurocognitive systems that explain resistance to temptation

  • a cool system which involves cognitive control-related brain circuits locatedin the INFERIOR FRONTAL GYRUS (located in the PRE FRONTAL CORTEX)
  • hot system which is related to emotion & desires ,, linked to emotional brain regions such as the VENTRAL STRIATUM

  
• → low delayer - someone who can't resist temptation

  • ventral striatum ,, want reward quicker

  → high delayer - someone who can resist temptation

  • inferior frontal gyrus ,, can wait for the reward
• aim

  → casey aimed to see if the ability to delay gratification or not was a consistent personality trait

  • i.e. whether it's a situational or a dispositional behaviour
  • it looked at whether the ability to delay gratification in childhood predicted impulse control later on in life

  → also aimed to see which regions of the brain were active when taking part in cognitive control tasks
• hypotheses

  1. lower delayers on the marshmellow test aged 4 would make more errors on a Go/No-go if the stimulu were 'hot' (rewarding emotional faces) than high delayers
  2. low delayers would show lower activity in their inferior frontal gyrus (as shown by fMRI brain scans)
  3. low delayers would show increased activity in the ventral striatum (where positive or rewarding cues are processed) compared to high delayers
• method ; 1

  → longitudinal study conducted over a period of about 40 years

  • participants were initially tested on delayed gratification when they were children in the 1960s and 70s ,, and then retested in their 20s and 30s
  • there data went into a pool of participants that Casey et al then selected participants from to take part in the present study
• method ; 2

  → in the present part of the study ,, participants took part in TWO QUASI EXPERIMENTS - the first used Go/No-Go tasks to test impulse control ,, second used fMRI scanners to assess participants' brain activity whilst completing Go/No-Go tests

  • in both experiments ,, the IV was whether the participant was a high or low delayer

  → in experiment 1 ,, the DV was the performance on Go/No-Go tasks (measured in terms of reaction times and accuracy)

  → in experiment 2 ,, the DV was the activity in the areas of the brain linked to impulse control (measured using fMRI scans)
• sample

  → ppts were chosen from a group of 562 participants who were all born between 1965-70 & had been tested on the Marshmallow Test aged 4

  • in 1963 (when ppts were in their 20s) ,, 155 of these ppts completed a follow-up questionnaire about self-control and 135 of these then completed a furthur follow-up self-control questionnaire in 2003 when they were in their 30s
  • 60/135 scored consistently low on all measures of self-control (low delayers)
  • 57/135 scored consistently high on all measures of self-control (high delayers)

  → these 59/117 people agreed to take part in the study
• samples in both experiment

  • experiment 1

  → 59 participants in total

  → 32 high delayers - 20 women ,, 12 men -mean age 44.6 years

  → 27 low delayers - 16 women ,, 11 men - mean age 44.3 years

  • experiment 2

  → 27 participants that took part in experiment 1 agreed to take part in experiment 2

  → 15 high delayers - 5 male and 10 female

  → 11 low delayers - 7 male and 4 demale

  → one male was taken out of the low delayers group because of poor performance so results for experiment 2 was based on 26 participants
• materials

  → experiment 1 tested participants on the Go/No-Go tasks on a pre-programmed laptop that was sent to participants' homes. social stimuli were used in the Go/No-Go tasks - these were photographs of people's faces displaying various emotions. these faces were drawn from the NimStim set of facial characteristics. two sets of male and female faces were used:

  • neutral faces (the 'cool' stimulus)
  • emotional faces - happy or fearful (the 'hot' stimulus)

  → experiment 2 used an fMRI scanner to assess brain activity
• experiment 1 ; procedure

  → participants were tested using laptops loaded with software that were sent to hem to use in their own homes - on this was a Go/No-Go task
• experiment 1 ; procedure ~ 1

  → participants were tested using laptops loaded with software that were sent to hem to use in their own homes - on this was a Go/No-Go task

  • they were first shown a target photograph then on each trial participants were shown another photograph - if the trial photograph matched the target photograph ,, they had to press a button ('Go' trial). if the trial photo didn't match the target photograph they had to resist any action and not press the buttion (a 'No-Go' trial)
• experiment 1 ; procedure ~ 2

  → participants were instructed to respond as quickly and accurately as possible - each face appeared for 500 milliseconds ,, followed by 1 second intervals between photographs. a total of 160 trials were presented per run in randomised order (120 Go trials ,, 40 No-Go trials)

  • each participant completed two versions of the Go/No-Go task ; a 'hot' version of the task in which the male and female faces showed emotional expressions (fearful or happy) and a 'cool' version in which the male and female faces had neutral expressions
• experiment 1 ; results ~ 1

  → Reaction times

  • there were no significant differences between high and low delayers in terms of reaction times on the Go trials

  → Accuracy

  • both groups performed with a high level of accuracy on the 'Go' trials in both 'cool' and 'hot' variations
  • errors on 'No-Go' tasks were put down to FALSE ALARMS ,, but whilst both groups made a similar number of errors on the 'cool' tasks ,, low delayers made more errors on the 'hot' tasks 

  
• experiment 1 ; results ~ 2

  → FROM TABLE ;

  • these findings suggest low self-control remains consistent in an individual - also shows that this depends on rewarding nature of the stimulus in the task ,, as the low delayers had more difficulty only on the happy face 'hot' task than the high delayers

  
• experiment 1 ; explanation of results ; 1

  → Casey concluded that the low delayers who had shown more difficulty in delaying gratification at Age 4 showed more difficulty as adult in supressing responses to happy faces

  • these findings suggest that low self-control remains consistent in an individual - also suggests that the ability to resist temptation varies by context ;
• experiment 1 ; explanation in results ; 2


  → the more tempting the choice for the individual ,, the less able low delayers are able to cope.

  → hot (emotional) stimuli are more tempting than fearful ones.

  • therefore ,, the ability to delay gratification depends on both cognitive control & how compelling stimuli that must be suppressed is
• experiment 2

  → in the second experiment ,, they aimed to investigate the regions of the brain that they predicted would be involved in self-control

  → they used an fMRI scanner - functional MRI scans are different from a MRI because an fMRI investigates how the brain works where as an MRI scan looks at the structure of the brain

  • Casey et al. predicted that the fMRI would show that regions of the brain would correlate with self control
• experiment 2 ; method/design

  → IV ;

  • high // low delayers

  → DV ;

  • activity in target areas of the brain that are associated with cognitive control (measured using an fMRI scanner)
• experiment 2 ; procedure ~ 1

  → 27/59 of participants who completed E1 also agreed to take part in E2. Participants completed a hot version of the Go/No-Go task similar to that used in E1.

  • didn't complete a cool task because no behavioural differences were shown between the high & low delayers in the cool task in E1

  → each face stimulus was presented for 500 miliseconds ,, with an interval ranging from 2-14.5 secs in duration (mean interval 5.2 secs). during this interval ppts had to stare at a crosshair on the screen
• experiment 2 ; procedure ~ 2

  → a total of 48 trials were presented per run in randomised order (35 Go trials and 13 No-Go trials) there were 2 runs - one with a happy and one with a fearful face. therefore ,, fMRI scan data was collected for 70 Go trials and 26 No-Go trials

  • one participant was excluded for excessively poor behavioural performance on the fMRI version of the task leaving 26 participants for analysis
• experiment 2 ; results

  → Reaction Times and Accuracy

  • no significant difference between the reaction times or accuracy of each group on the Go/No-Go tasks

  → Brain imaging

  • the low delayers showed reduced activity in the right inferior frontal cortex than the high delayers on the No-Go trials
  • the low delayers showed higher activity in the ventral striatum ,, specifically when the happy faces were the No-Go stimulus
• experiment 2 ; explanation of results ~ 1

  → the ability to resist temptation is stable individual characteristic. this was shown in study over a 40 year span as those who had been low delayers at age 4 years had more difficulty suppressing responses to socially alluring cues as adults. ability to delay gratification is more to do with the ability to resist alluring cues (e.g. happy faces) rather than a problem with cognitive control in general
• experiment 2 ; explanation of results ~ 2

  • study provides evidence that there are 2 neurocognitive systems that enable self control ;

  → 'hot' system - in ventral striatum - involved in processing or desires and rewards

  → 'cool' system - in prefrontal cortex incl. inferior frontal gyrus
• evaluation ; strength ~ 1

  → Casey tested the behavioural correlates of deferred gratification under strictly controlled conditions - means the study highly replicable due to its standardised procedures & strict control ,, allowing reliability to be assessed. the software used for the Go/No-Go Go tasks recorded reactions of the participants within split second accuracy and the fMRI scans provided objective data that allowed the researchers to draw conclusions between the two groups
• evaluation ; strength ~ 2

  → the study was conducted longitudinally as it was following up on a group of participants who had been tested at age 4 ,, in their 20s ,, 30s & in this study ,, their 40s. - it allowed the researchers to say that the ability to resist or not resist temptation is a relatively stable characteristic & therefore provided more valid data about the participants

  → study collected quantitative data which allows the results from both experiments to be presented and summarised easily in graphs and tables. this also makes the results from each participant group to be compared
• evaluation ; weakness ~ 1

  → a longitudinal study with a large sample is subject to high drop out rates - participants can choose not to continue which makes the study sample reduce in size and therefore can make the sample less generaliseable as the participants left in the study will likely have similar characteristics ,, such as an interest in the study. this was shown in the study as E1 only had 59 participants and E2 had 27 participants from the original sample of 562
• evaluation ; weakness ~ 2

  → as both experiments were quasi experiments (IV of high/low delayers was naturally occurring) ,, this means researchers couldn't randomly allocate participants to one group or the other. therefore ,, they have less control over participant variables.

  → the study lacked ecological validity and mundane realism - using a split-second stimulus in a contrived test doesn't have a direct equivalent in everyday life. similarly ,, being scanned by an fMRI scanner while doing the Go/No-Go task isn't something a person would have to do in everyday life
• conclusions

  → resisting temptation (or not) is a relatively stable individual characteristic. the study was done over 40 years ,, those who were low delayers at age 4 had more difficulty supressing responses to socially desirable cues later in life

  → delay ability is hindered by alluring cues specifically ,, and isn't a problem with cognitive control in general

  → it provides evidence for the hot and cool systems in the brain. the hot system in the ventral striatum and the cool in the inferior frontal gyrus