Casey et al

Casey et al

1. Method

   • Quasi experiment
     • IV: high/ low delayer
     • DV: performance on impulse control task and imaging from fMRI
   • Repeated measures design
   • Longitudinal

2. Aim

   • To find out if participants who were low delayers on the Marshmallow Test at age four would..........
     • Show more errors on a Go/No go task if the stimuli were hot than the high delayers
     • Show lower activity in their right prefrontal cortex suggesting lower response inhibition
     • Show increased activity in the ventral striatum, where positive/ rewarding cues are processed

3. Participants

   • Marshmallow Test
     • 562
     • Aged 4
   • Follow up in their 20s
     • 155 of the original sample
   • 2003 follow up
     • 135 of original sample
       • 60 low delayers
       • 57 high delayers
   • This study
     • 59 of original sample
       • 27 high delayers
       • 32 low delayers
       • 36 F
       • 23 M
       • 26 in experiment 2
         • 1 removed due to low score
         • 15 high 11 low delayers

4. Procedure

   • Experiment one
     • Cool version of Go/No go
       • Male and female stimuli
     • Hot version of Go/No go
       • Fearful and happy facial expressions
     • A screen came up indicating which stimuli was the target
     • Press a button for Go stimuli
     • Asked to respond quickly and accurately
     • Shown for o.5 seconds
       • 1 second intervals
     • 160 trials
     • On laptops in participants home
   • Experiment two
     • Done in a fMRI scanner
     • Hot version of the go/no go task
     • shown for 0.5 seconds
       • Varying intervals
     • 48 trials
     • For each expression
       • 26 no-go
       • 70 go

5. Results

   • Experiment one
     • All participants performed with high levels of accuracy in the go trials in both hot and cool trials
     • Low delayers committed more false alarms in the no go trials
     • Low delayers performed more poorly on the hot trials than high delayers
     • Go/ no go task produced differences between delay groups in the presence of emotional hot cues
       • Hard to suppress responses to happy faces
   • Experiment two
     • No significant difference in reaction time
     • Accuracy was high for go trials
     • Low delayers committed more false alarms
     • Right inferior frontal gyrus was involved in accurately withholding a response
     • Low delayers showed higher activity in the ventral straitum
       • When hot stimuli = no go
         • Alluring features makes it harder to resist

6. Evaluation

   • Validity
     • High in design validity
       • Highly controlled conditions
       • Extraneous variables controlled
     • Low population validity (see sample)
     • Low ecological validity
       • may not tell us how people respond under normal conditions
       • fMRI is not a usual thing to do
       • Unfamiliarity may have impacted performance
   • Reliability
     • Hard to establish reliablility
       • Longitudinal study
         • Hard to repeat
         • Expensive
   • Ethics
     • All ethical guidelines followed
     • Clearly had the right to withdraw
   • Data
     • Quantitative
       • Easily compared
       • Easily summarised
       • Easily repeated and tested for reliability
   • Sample
     • People dropped out
     • Becomes a small sample
       • Cannot generalise to original sample
     • Those who continue may all be a certain type of person
     • fMRI didnt look at many females
       • Cannot generalise
   • Ethnocentrism
     • Investigated a species specific behaviour
     • Only America
       • Culture of capitalism
         • Caused more low delayers???
   • Research Method
     • Use of technology
       • Detailed and objective observation
     • Longitudinal
       • Come to the conclusion that it continues for whole life
       • Subject attrition
       • Take a long time

7. Usefulness

   • Resisting temptation is important for individual, societal, and economic functioning
   • High delayers cope better in adolescence
   • Train the brains of low delayers to reduce their vulnerability

8. Links to area/perspective

   • Specific regions of the brain control impact our ability to control temptation
   • Could be individual differences
     • Different abilities to delay gratification
       • Stays for whole life

9. Links to key theme

   • Two regions of the brain that help us resist temptation
   • Evidence for 'hot' and 'cool' systems that affect self control
   • Tells us the role of another region of the brain
   • Suggests another way to research regions of the brain

10. Links to debates

    • Psychology as a science
      • Fulfils the scientific criteria
      • Supports the claim that psychology is a science
    • Nature/ Nurture
      • Born low/high delayers
        • Stays throughout life
      • By 4 we have been modeled to wither resist temptation or not
        • Train people to become high delayers
    • Free will/ determinism
      • Born with brain differences that cause us to be high or low delayers
        • Determined