Barkley-Levenson Study

• Aim


  to identify if there is any difference in neural/brain activity between adolescent and adult brains when given risk-taking scenarios
• 3 hypotheses

  1. adolescents will accept more gambles of increasing expected value than adults2. ventral striatum activation will increase in proportion to increasing EV in adolescents3. adults who behave like adolescents will not exhibit hyperactive ventral striatal activation
• method


  lab based quasi experiment, independent measures,

  IV: adult or adolescent,

  DV: difference in brain activity in ventral striatum & if participant gambled or not
• sample


  self-selected (posters/internet adverts), 19 healthy adults, aged 25-30, 22 healthy adolescents, aged 13-17, males and females, all right-handed
• session 1


  'intake session' in a lab, participants gave consent (themselves or parents), asked about spending money per month (mean adolescents: $52.50, mean adults: $467), then given $20 and told to bring to session 2 following week
• session 2


  one week later, participants told to use $20 from last session as gambling money, told there was a chance to win $20 more or lost the $20, placed in fMRI scanner, asked to complete gambling task
• gambling task


  participants shown a series of gambles under a screen when getting fMRI scan, 50% gain, 50% lose, range of profits and losses between $5 and $20, total of 144 trials, participants had to decide if they wanted to gamble for real money
• expected value (ev)


  sum of all possible outcomes of particular choice multiplied by probabilities, risk vs reward judgement (change of winning)
• results - behavioural

  • no significant difference when there was no risk (gain only or loss only), all trials with positive EV were accepted more, amount of disposable income did not have an effect, no differences in reaction times
  • the higher the EV the more likely an adolescent was to gamble, 65% compared to 48% adults - adolescents focus on higher amount, not concerned with what they will lose
• results - neural


  fMRI showed that adolescents had greater activation in ventral striatum compared to adults, also showed that adolescents had decreased activity in the amygdala (responsible for fear)
• conclusion


  adolescents behave similarly to adults when there is no risk, however adolescents place greater value on rewards than adults, leading to risk takingadolescents also show greater activity in the ventral striatum, their brains focus on rewards instead of consequences