Casey et al (2011)

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  • Created by: EmilyHolt
  • Created on: 04-03-16 19:18
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  • Casey et al (2011)
    • Results
      • Experiment 1
        • No significant differences between high and low delayers in terms of reaction times.
          • No significant differences on Go trials. 99.8% correct on cool and 99.5% correct on hot tasks.
            • Both groups made mistakes on NoGo trials. False alarms rate - 9.96% on cool task. 12.2% on hot task.
              • Low Delayers made more errors on hot tasks.  Largely errors on happy face trials.
      • Experiment 2.
        • No significant differences between High and Low delayers on terms of reaction times.
          • Both groups highly accurate on Go trials.
            • Low delayers more false alarms on NoGo trials (14.5%)
              • Low delayers reduced activity in the right inferior frontal cortex on NoGo trials.
                • Low delayers higher activity in ventral striatum - more with happy face stimulus for NoGo trials.
    • Participants
      • 565 participants aged 4 - Marshmellow Test.
        • 1993, 155 of the original (now in twenties) - Questionnaire on self control.
          • 2003, 135 of the second group (now in thirties) - Follow up self control questionnaire.
            • 117 chosen to take part (either consistent high or low delayers).
              • 59 agreed to take part.
    • Conclutions
      • Low Delayers when aged 4 - difficulty supressing responses to happy faces when adults.
        • This suggests low self control consistent in an individual.
          • Also, resisting temptation varies by context (more tempting choice 'hot' stimulus.
            • ability to dleay gratifiiction depends on cognitive control and the compelling stimulus.
      • Evidence that there are two neurocognitiv systems that enable self control.
        • Evidence for effects from Ventral Striatum and Inferior Frontal Gyrus.
    • Evaluation
      • Strengths.
        • Strictly controlled conditions = highly replicable.
          • Longitudinal study = more in depth valid data on participants.
            • Quantitative data = statistics and graphs which are easily compared.
      • Weaknesses.
        • Large sample = Attrition more likely to occur. Less generalisable as participants who drop out may have similar characteristics.
          • Quasi experiments = less control over participant variables as IV naturally occuring.
            • Tests and fMRI = lacks ecological validity as not real life situations.
    • Aim
      • To see if the ability to delay gratification or not was a consistent personality trait.
        • whether it was a situational behaviour
        • whether it was a dispositional behaviour
    • Method
      • Longitudinal study over 40 years.
        • two quasi experiments. IV in both was whether participants were HIGH delayers or LOW delayers.
          • experiment 1.
            • performance on Go/No Go task. Reaction times and accuracy measured.
              • tested using laptops at their homes.
                • Shown target photograph of a face. Shown another photograph on each trial - if photograph matched the target they pressed a button. (GO)
                  • If trial photograph did not match target they had to RESIST and not press a button.      (NO GO)
                    • Each face shown for 500 milliseconds - 1 second interval between photos.
                      • 160 trials in total -          120 GO/       40 NO GO.
                        • Two versions were completed by all - 'hot' when facial expressions were shown.    'cool' when the faces were neutral.
          • experiment 2.
            • 27 of 59 in exp, 1 agreed to take part.
              • Completed 'hot' version of Go/No Go test.
                • Photo shown for 500 milliseconds, mean interval 5.2 seconds.
                  • Participants told to stare at crosshair on screen during intervals for  fMRI scanner.
                    • 48 trials per run (35 GO/ 13 NOGO). two runs - happy stimulus and fearful stimulus.

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