Psychology - Core Studies - Casey (2011)

title?

“Behavioural and Neural correlates of delay of gratification 40 years later,”

aim?

• to see whether the same individuals who resisted at pre-school could resist in adulthood,

• to see whether those classed as ‘Low Self Control’ from psychometric tests in their 20s and 30s would show more errors on a go/no-go task,

• to see if Low Delayers would have a) lower activity in the right pre-frontal cortex, b) increased activity in the Ventral Striatum,

method?

Longitudinal Experiment, Quasi (Low/High delayers)

design?

repeated measures (test in 20s/30s and then later, hot and cool go/no-go task)

experiment 1 participants?

• 562 pupils at Bing Nursery School (1964-70),

• 155 completed self-control test in 20s → 135 completed in 30s,

• 117 were contacted because they were above/below average score,

• 59 consented (23M and 36F)

  • 27 low delayers (11M and 16F),

  • 32 high delayers (12M and 20F),

• controlled extraneous variables - similar numbers of M and F in each group,

procedure experiment 1?

1. participants given pre-programmed laptops with go/no-go tasks,

2. completed task at home, instructions appearing on the screen,

3. pictures of faces would appear for 500ms with a 1s delay between faces,

experiment 1 tasks?

Cool 1 - go = male neutral face, no-go = female neutral face,

Cool 2 - go = female neutral face, no-go = male neutral face, (opposite of 1)

Hot 1 - go = happy face, no-go = fearful face,

Hot 2 - go = fearful face, no-go = happy face, (opposite of 1),

results of experiment 1?

high levels of accuracy - cool = 99.8%, hot = 99.5%,

both high and low delayers made more errors on no-go,

cool tasks = same number of errors made by high and low delayers,

hot tasks = low delayers made more errors on the no-go tasks,

low delayers = 15.7% error on happy no-go, 12% error on fearful no-go,

high delayers = 11.2% error on happy no-go, 10.4% error on fearful no-go,

LD at 4yrs and those classed as ‘Low Self Control in their 20s and 30s’ showed more difficulty suppressing responses to no-go presentations in their 40s,

procedure experiment 2?

go/no-go task at medical facility,

delay between presentation of faces varied between 2-14.5 seconds,

35 go and 13 no-go slides (48),

Run 1 - go = fearful, no-go = other,

Run 2 - go = happy, no-go = other,

conducted in an fMRI with the person still other than the button,

aim experiment 2?

to investigate the regions of the brain implicated in self-control,

experiment 2 participants?

27 from experiment 1,

13M and 14F,

11 LD - 7M and 4F,

15 HD - 5M and 10F,

experiment 2 results?

both groups highly accurate on go trials,

LD on no-go tasks = 14% errors, HD on no-go tasks = 10.9%,

activity in interior frontal gyrus and ventral striatum:

• LD have lower activity in IFG (cool system) cf HD,

• LD show higher activity in VS (hot system) cf HD,

• hot features made the ventral striatum more active in LD cf HD,

conclusions?

• resistance to temptation appears to be a relatively stable characteristic, doesn’t change much over a lifetime,

• cognitive control can be influenced by contextual facts e.g., hot cues,

• LD when faced with temptation have a) reduced activity in IFG, b) increased activity in VS,

validity?

Face → go/no-go tasks measure delay gratification, can a person hold off on no-go,

Construct → some control of extraneous variables - higher in experiment 2, lower in 1,

Concurrent → results of tests align with other studies, experiment 1 and 2 showed similar results,

Ecological → high as most people can be put as high or low delayers, lowered for experiment 2 as fMRI is an unnatural situation,

Temporal → teenagers have higher risk-taking and higher activation in ventral striatum,

reliability?

internal → results of each experiment show the difference between hot and cool systems, variety of go/no-go tests with different activations show similar results,

external → results between individuals were generally similar and didn’t change over time - LD were classed as LD again,

usefulness?

applied to behavioural therapies such as anger management,

generated further research