casey

• delay by gratification


  an ability to put off something fun/pleasurable now in order to wait for something that is greatly fun/pleasurable for rewarding later
• cognitive control


  ability to suppress competing inappropriate thoughts or actions in favour of appropriate ones
• original procedure

  • children classed into two categories - low delayers and high delayers
  • the ability to resist temptation depends on cognitive control, and it seems that some people have better self-control than others
  • can be predicted by performance on the marshmallow test
• why are there these differences?

  • those who couldn't resist the marshmallow on their first go could wait longer when retested if they were taught to use cooling strategies - reduce the appeal of the award
  • we respond hot and cool cues differently as we can resist cold cues more than hot cues
• hot cues


  elicit an instant, emotional response - rewarding hot cues are linked with our desires and positive emotions
• cool cues


  takes the emotion away from a stimulus - not emotionally rewarding, neutral
• Metcalfe and Mischel (1999)

  • suggested that there is a 'cool' system in our brain located in the prefrontal cortex called the inferior frontal gyrus - associated with deciding whether to resist or not, more active in high delayers
  • hot system related to emotion and desires is in a different area called the ventral striatum - related with emotion, desires and rewards, more active in low delayers
• aim

  if people who were low delayers in the original marshmallow test would still have low self-control in their 40s
• casey's experiment

  • needed to come up with a different way to measure how consistent self-control (or lack of) is throughout life
  • tracked down participants who were in the original marshmallow test when they were 4 (now 40) - longitudinal study
• experimental method

  quasi experiment

  • IV was naturally occurring - individual participants' ability to delay gratification
• experiment 1

  • self control measured by a go/no-go task
  • requires participants to push a button when they see a certain stimulus, and not press a button when they see a different one
  • 59 ppts (32 high delayers and 27 low delayers) did 4 tasks at home on a laptop delivered to their home
  • instructions appeared on the screen before each task saying which face (male/female neutral face; fearful or happy face) was the target stimulus and not to press the button for the other face
• experiment 2

  • 26 ppts (15 high delayers and 11 low delayers)
  • ppts were scanned in a functional magnetic resonance imaging scanner (fMRI) whilst completing the 'hot' version of the go/no-go task similar to experiment 1
  • each face stimulus was shown for 500ms with a 2 to 14.5 second interval
  • task was seen through a rear projection screen
  • electronic response pad was used to record responses to facial stimuli and reaction times
• both groups were highly accurate in their correct responses to 'go' trials in both the cool and hot conditions (99.8% and 99.5%)
• low delayers made more errors in the no-go trials in the hot conditions
• accuracy and reaction time


  were recorded during the experiment
• key region of the brain used in withholding responses

  right inferior frontal gyrus - low delayers showed reduced activity in this region during no-go trials
• during trials involving the most alluring stimuli, part of the limbic system known as the ventral striatum was more active in low delayers than in high delayers
• conclusion 1

  resistance to temptation appears to be a relatively stable characteristic of an individual over time
• conclusion 2

  cognitive control can be strongly influenced by contextual factors (e.g. hot cues) in alluring situations
• conclusion 3

  ventral frontostriatal circuitry supports resistance to temptation, with a combination of lowered activity in the inferior frontal gyrus and increased activity in the ventral striatum in low delayers
• number of participants in the original marshmallow experiment completed when they were 4

  562
• throughout the years, self-control self-report survey was given and completed (attrition)
• research method - strength

  • experiment 2 - under laboratory conditions, was possible to control extraneous variables
• research method - strength

  • experiment 1 - used a carefully standardised programme to present stimuli and recorded participant responses with a high level of reliability and accuracy, avoiding human error
• research method - weakness

  • behavioural task from experiment 1 was performed by ppts in their own homes, greater possibility of distractions in the environment
• sample - weakness

  • initial 562 ppts attended one nursery during a specific time period - findings are geographically limited and may not represent people from similar family backgrounds
• sample - weakness

  • not everyone from the original delay of gratification task took part
• sample - ethnocentrism

  • impulse control is nurtured differently in different societies, which means that cross-cultural differences could be noted
• data - strength

  • quantitative data which allows for direct comparison of conditions - showed that young children who performed poorly on the original task later showed diminished cognitive control in alluring situations as adults
• data - weakness

  • able to observe the differences between low and high delayers but no information about why their brains and behaviour varied significantly
• ethics - strengths

  • informed consent from ppts for both experiments
  • fMRI considered low risk - protection of participants from harm was assured
• reliability - strength

  • level of control involved in laboratory experiments is reliable
• reliability - weakness

  • used an fMRI scanner to examine results, unlikely to get similar results if the experiment was repeated using the same equipment
• validity - weakness

  • ecological validity was weak - nature and presentation of the go/no-go task was artificial and different to how we normally encounter and respond to facial expressions
• validity - weakness

  • used fMRI scanners which could have made an impact on the way in which ppts responded to stimuli, likely that genuine social interactions are more complex and may cause brains to behave differently from how they behave in artificial conditions
• practical applications

  • provided further evidence about the localisation of neutral function for tasks involving rewards and resisting temptation. Also found that our ability to exercise self-control is influenced greatly by contextual cues