Casey (delay of gratification)

• Aim - to test if delay of gratification in childhood predicts impulse control abilities and sensitivity social cues at the behavioural and neural level as adults
• Background - performance on delay of gratification tasks as children predicted efficiency of the same individuals on cognitive control task (go/no go task) as adolescents and young adults
• Research method - lab experiment (quasi/natural as IV not natural)/ longitudinal
• Sample - did delay gratification tasks at Stanford Nursery as young children and self control scales in 20s and 30s. 59, ahove or below average in original studies took part in classified as experiment 2
• Procedure - IV: low or high delayer DV: reaction time and accuracy on impulse control task
• Experiment 1 - low (27 participants, 11m 16f) or high delayers (32 participants, 27m 20f) - independent measures design
• Experiment 1 - completed two go/no go tasks

  Before each run, a screen gave target for button press. Had to be quick and accurate as possible

  Each face appeared for 500ms, with 1s between each face. Total of 160 trials randomised (120 go, 40 no go)

  The tasks were presented using programmed laptop computers sent to participants homes
• Results of experiment 1 - accuracy: low and high delayers similar accuracy on go trials Reaction times: low delayers perform more poorly on no go hot task
• Experiment 2 - independent measures design completed in functional magnetic resonance imaging scanner
• Experiment 2 - hot and cold version of go/no go task similar to experiment 1. Differences in timing, number of trials and apparatus

  Face presented for 500ms, slightly longer delay and had 48 trials (35 go, 13 no go). Task viewed on rear projection screen and recorded using a neuroscreen five button response pad
• Results of experiment 2 - differences same as experiment 1: imaging results showed low delayers had lower activity in the right prefrontal cortex (higher order thinking) and higher activity in ventral striatum (reward) compared to high delayers
• Conclusion - those who, at four years, have difficulty delaying gratification and continue to show reduced self control abilities, have more difficult as adults in suppressing responses to positive social cues than those who didn't
• Delay of gratification depends on cognitive control and there appear to be natural differences in our spontaneous use of different strategies to achieve this.
• Jabbi and Keysers (2008) - Inferior front gyrus had a key role in interpreting facial experssions and appropriate emotional response.

  A correlation between avoiding risky heaviour and greater activity in the right inferior frontal gyrus.
• The ventral striatum helps balance motivation in higher and lower level brain functions. It is the region in the basal ganglia neural circuit most closely connected to reward.
• The limbic or emotional brain regions, including the ventral striatum are shown to be associated with more immediate choices and rewards.
• Performance in preschool delay of gratification tests may predict the capacity to control thoughts and actions as adults, as seen in performance on cognitive control tasks
• Those who as pre-schoolers directed their attention toward rewarding aspects of the classic delay-of-gratification situation had more difficulty suppressing inappropriate actions than their low-temptation-focus counterparts
• Alluring or social contexts can reduce self-control
• The aim of the study was to assess whether delay of gratification in childhood predicts impulse control abilities and sensitivity to alluring or social cues (happy faces) at the behavioural and neural level when participants were in their 40s
• Research method - Quasi/natural experiment as independent variable - participant either a high delayer or a low delayer was naturally occurring and so could not be manipulated or controlled by the researchers.

  Longitudinal study following some of the original participants from the age of four until into their 40s.
• Sample - 562, 4y old pupils from Stanford Bing Nursery completed delay-of-gratification task during 1960s and early 1970s. 155 of these completed self-control scales in their 20s and 135 in their 30s.

  117 of those 135, who were either above or below average in original delay-of-gratification performance as well as in self-report measures of self-control were asked to take part in this study.

  41y old man removed due to poor performance on fMRI task so results for EXP 2 based on only 26.
• Key findings in EXP 1 - Low and high delayers similar accuracy on Go trials. NO GO trials more variable, with low delayers committing more false alarms than high delayers.

  Low and high delayer similar accuracy on COOL task. Low delayers perform more poorly on HOT task.

  High delayers equally accurate on COOL and HOT trials.
• Candidate regions of the brain differentially engaged as a function of cognitive control tasks
• Right inferior frontal gyrus involved in accurately withholding a response
• Low delayers had diminished recruitment of the inferior frontal gyrus for correct NO GO compared to GO trials
• Ventral striatum showed significant difference in recruitment between high and low delayers
• Prefrontal cortex differentiated between NO GO and GO trials to a greater extent in high delayers
• Ventral striatum showed exaggerated recruitment in low delayers
• Sensitivity to environmental hot cues significantly affects an individual's ability to suppress actions towards alluring cues
• Resisting temptation is a stable individual difference and predicts biases on frontostriatal circuitries integrating motivational and control processes
• Ability to resist temptation varies by context, with more tempting choices predicting behavior based on individual differences in delaying gratification
• Ability to delay gratification depends on both the type of temptation and the brain area being used