Casey - Brain regions

• Background: What was the procedure carried out on the ppts when they were 4?

  • Given marshmallow and told to wait and not eat it yet 
  • Children were divided into 2 categories: High delayers – could wait and receive reward of 2 marshmallows Low delayers – could not wait and took immediate reward of eating the marshmallow 
  • DV – ability to resist temptation depends on cognitive control 
  • High delayers were able to resist because of cooling strategies which reduced the appeal of the reward
  • We respond to hot and cold cues differently as we can resist cold cues more than hot cues 
• Background: What did Metcalfe and Mischel suggest?

  • Suggested there is a “cool” system in the inferior frontal gyrus in the pre-frontal cortex which is more active in high delayers 
  • The “hot” system is related to emotion and desires in the ventral striatum which is more active in low delayers 
• What was the aim?

  To see if people who are low delayers in the original marshmallow tests would still have low self control in their 40s 
• What was the method?

  Quasi experiment (high or low delayer) 

  Longitudinal over 40 years 
• What was the sample?

  • 562 original ppts in the marshmallow test when they were 4 years old 
  • 59 ppts in experiment 1 (27 low delayers and 32 high delayers) 
• What was the DV of experiment 1?

  • Self control was measured by the Go / No-Go task 
  • This required ppts to push button when they see certain stimuli and not push when they see a different one 
  • This task had hot and cold stimuli to see how responses differed 
  • Hot stimuli – rewarding stimulus – happy face 
  • Cool – neutral or fearful faces 
  • This was done to see if low delayers would make more errors because the brain couldn’t control the response to the hot cue 
• What was the procedure of experiment 1?

  • Each of the 59 ppts did 4 of these at home on a laptop that was delivered to their homes  
  • Each face appeared for 500ms with a 1s interval 
  • Instructions appeared on the screen saying which face was the target stimulus (e.g. male happy face) and not to press the button for the other face 
  • Target – GO – happy face 
  • NO-GO – fearful face 
• What were the results of experiment 1?

  • Ppts who could delay gratification as a child showed greater ability to suppress impulse control as an adult 
  • No significant difference between high and low delayers in terms of reaction times 
  • Low delayers performed less well than high delayers on hot tasks  
• What was the aim of experiment 2?

  • To investigate regions of the brain that they predicted would be implicated in self control
• What was the procedure of experiment 2?

  • Use fMRI to look at physiognomy of brain 
  • 27 out of the 59 ppts from experiment 1 agreed to be tested (1 male excluded due to poor task performance) 
  • Repeated measures (ONLY IN EXP 2) as GO / NO-GO task done again in scanner 
  • 26 (15 high delayers and 11 low delayers) each took part in the similar GO / NO-GO task as exp 1 with fearful / happy faces 
  • Instead of a 1 second delay there was a 2 – 14.5 second delay between faces to allow the scanner to process brain activity  
• What were the results of experiment 2?

  • Both groups scored high on accuracy for go trials and low delayers show more false alarms 
  • Imaging showed 2 main differences between high and low delayers  
  • Low delayers showed reduced activity in the right inferior frontal gyrus than high delayers 

  
• What were the conclusions?

  • Resisting temptation is a relatively stable individual characteristic and low delayers at 4 had more difficulty suppressing responses to happy faces 
  • Ability to delay is hindered by alluring cues and not a general problem with cognitive control 
  • Empirical evidence for Mischel and Metcalfe’s “hot and cold” processing system that affects self control in the brain 
• What was the usefulness?

  • Addictions and anti-social behaviour can be predicted from a young age