Casey Et Al

• Background

  • marshmallow test, child taught If they wait for 15 minutes they can have 2 marshmallows

  high delayer - Can wait and get two marshmallows ( Can use cognitive strategies that redirect attention which is known as cold cues )

  low delayer - can't wait and ate marshmallow ( focus on rewarding aspect such as sweet taste which is know as hot cues )

  • Brain regions - two systems that explain resistance to temptation

  Cool system : involves cognitive control - related brain circuits located in inferior frontal gyrus

  Hot system - emotion and desires located in ventral striatum
• Aim

  Aimed to see if ability to delay gratification or not was a consistent personality trait.

  See whether its a situational or dispositional behaviour

  See which regions of the brain were active when doing cognitive control tasks
• Hypotheses

  1. Low delayer on marshmallow test would make more errors on GO/NO GO than high delayers
  2. High delayers would show increased activity in inferior frontal gyrus
  3. Low delayers have increased activity in ventral striatum
• Method

  • longitudinal study over 40 years
  • Initially tested on delayed gratification as children were tested and retested in 20s and 30s
  • Casey selected some of these to take part in the study
  • took part in one go no go task
  • when it was a go task it required an action
  • when it was a no go it didn't require action and was used to test impulse control.
  • 2nd experiment used FMRI scanners whilst doing the tasks
• Sample

  • Chosen from 562 participants
  • Born between 1965 - 1970
  • 117 people were contacted
  • exp 1 - 59 participants agreed - 32 high delayers 27 low delayers
  • exp 2 - 27 but took out on persons data so 26 - 15 high delayers 11 low delayers
• Procedure - Experiment 1

  • shown trial photo and if the trial photo matched photos they had to press the button and respond asap. They were each shown for 500 milliseconds.
  • 1 second interval between the photos
  • 'hot' emotional expressions
  • 'cold' neutral expressions
• Results - Experiment 1

  • no difference in reaction times
  • both groups made errors on No-Go
  • low delayers made more errors on 'hot'
  • Happy expressions = Low delayer errors - 15% and high delayers - 11%
• Explanation of experiment 1 results

  • Low self control remains consistent as an individual.
  • Ability to resist varies by context
  • Ability to delay is situational and individual
• Procedure for experiment 2

  • Hot version of Go-No G
  • Face stimulus presented for 500 milliseconds
  • FMRI scan data collected for 70 Go and 26 No Go
  • 26 participants data used
• Results for experiment 2

  • no significant differences in reaction times
  • Low delayers show reduced activity in right inferior frontal gyrus and higher activity in ventral stratum - reward centre. Harder for them to resist
  • High delayers showed higher activity in right inferior frontal gyrus - decision making centre
• Explanation of experiment 2 results

  • the ability to resist temptation is a stable individual characteristic
• strengths of the experiment

  • tested under strictly controlled procedure - highly replicable
  • Tested longitudinally - allowed them to say whether resisting temptation is a stable characteristic - more valid
  • Collective quantitative data - easily comparable
• Limitations

  • longitudinal with large study is subject to attrition which can make it less generalisable because all participants left have something in common
  • Less control over participants as quasi experiment
  • Lacked ecological validity and mundane realism, being scanned in an FMRI scanner isn't something you'd do