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Individual Differences in Choice Lecture

Outline of Individual Differences in Choice

  • Overview of the lecture topics
    • The origin of individual differences
    • Neurotransmitters & Hormones
    • Differences in risk attitudes
    • Differences in time preferences
    • Differences in social decision-making
    • Changes across the lifespan

Neurotransmitters & Hormones

Definitions and Roles

  • Neurotransmitters:
    • Chemicals produced in the brain.
    • Fast-acting (milliseconds to minutes/hours).
    • Examples: Dopamine, Serotonin, Noradrenalin.
  • Hormones:
    • Chemicals produced mainly outside the brain.
    • Slow-acting (minutes to hours/days).
    • Examples: Testosterone, Oxytocin, Estrogen.

Impact on Behavior and Choice

  • The levels of neurotransmitters and hormones in the nervous system determine:
    • Gain/amplitude of emotional/cognitive functions.
    • Individual differences in feelings, behavior, and decision-making.

Differences in Risk Attitudes

Dopamine's Influence

  • Dopaminergic Reward System:
    • Areas producing dopamine are significant for rewards and value in decision-making.
  • Risk Attitudes:
    • High Dopamine (DA) levels are related to increased risk-seeking behaviors.
    • Evidence cited from Onge & Floresco, 2009.
  • Aging and Decision-Making:
    • There is a 5-10% loss of DA per decade, affecting the striatum and cortex.
    • Adolescents have a peak of dopamine receptors, leading to different reward evaluations compared to adults.

Adolescent Dopamine and Risk Perception

  • Dopamine levels in adolescents are approximately 30-40% higher than in adults, resulting in:
    • An imbalance between reward-seeking (DA) and harm-avoidance (5-HT) processes.
    • Adaptations for better learning and exploration.
  • Research indicates adolescents display different striatum activation patterns during reward anticipation versus reward reception.
    • Activation Patterns:
    • More activation during rewards than during anticipation, helping to evaluate rewards.

Role of Serotonin

  • Serotonin (5-HT):
    • High levels lead to risk-aversion.
    • Low levels correlate with risk-seeking behaviors.
  • Influence on Risk Attitudes:
    • Findings from Long et al., 2009 suggest that serotonin depletion reduces risk aversion by lowering thresholds for risk.
    • Diet impacts risk-taking; for example, a higher meat intake positively correlates with serotonin levels.

Connection Between Dopamine and Serotonin

  • High Dopamine, Low Serotonin:
    • Tend to seek risks (reward-seeking).
    • Dopamine stimulates reward circuits (striatum, vmPFC).
  • High Serotonin:
    • Inhibits reward circuits, associated with prevention of harm and loss.

Implications for Hormones on Risk Attitudes

  • Low evidence indicates that oxytocin affects risky choice.
  • Testosterone shows mixed effects on risky choices, depending on individual differences and environmental factors.

Individual Time Preferences

Relation to Risky Choices

  • Inter-temporal Choice:
    • The decision-making process reflects a choice between a smaller immediate reward versus a larger future reward, indicated by the timing and certainty of rewards.
  • Investigating how dopamine and serotonin influence inter-temporal choice compared to risk preferences is vital.

Dopamine's Role in Time Preferences

  • Studies and Findings:
    • Based on research from Van Gaalen et al., 2005, various dopamine agonists (such as methylphenidate) can either increase or decrease patience based on receptor subtypes.
    • Aging correlates with increased patience in regards to time preferences.
    • The effects of drugs like amphetamines and Ritalin show complex interactions with both dopamine and serotonin functions.

Serotonin's Impact

  • Link Between 5-HT and Patience:
    • Serotonin appears to enhance patience, as shown in studies including Denk et al., 2005.
    • Substance pCPA is identified as a serotonin antagonist, further validating its role in inhibiting risk-taking behaviors associated with future rewards.

Social Decision-Making

Hormonal Influences: Oxytocin & Testosterone

  • Oxytocin:
    • Associated with labor, breastfeeding, mother-infant attachment, and social bonding.
    • Plays a role in enhancing trust but does not necessarily increase reciprocity in social settings.
  • Testosterone:
    • Influences social behavior through impulsivity and aggression.
    • Related to social dominance and increased sensitivity to social threats, following the Challenge Hypothesis, where testosterone helps individuals respond to challenges, both social and physical.
  • Trust and Reciprocity:
    • Evidence suggests that testosterone decreases trust while increasing reciprocity.

Key Studies and Findings

  • Game Theory & Trust Games:
    • Research by Kosfeld et al., 2005, demonstrates oxytocin's modulation of social preferences in trust-related decisions.
    • Testosterone levels impact social preferences, shown by variations in player responses in competitive sports contexts.

Summary of Key Findings

  • Dopamine enhances motivation to seek rewards while serotonin motivates safety-seeking behaviors.
  • Hormones like oxytocin increase the inclination to affiliate, while testosterone strengthens the drive to dominate and maintain high social status.
    • Individuals exhibit varying preferences influenced by their neurochemistry and life experiences.