Utility: psychological value assigned to an outcome.
Prospect theory
- Prospect: option whose future rewards and probabilities are known or can be estimated.
- It is a descriptive theory: it describes what people will choose instead of should do.
- It differs from the expected-utility theory in two ways:
- Reference dependence: current state is a reference point
- Reference point
- Diminished sensitivity
- Loss aversion
- Probability weighting: subjective perception of probabilities
- Possibility effect: a chance is better than no chance
- Certainty effect: no risk is better than some risk
Primary reinforcer: rewards that have a direct benefit for fitness
Secondary reinforcer: neutral outcome that has been turned into a positive one
Substantial nigra and ventral tegmental area are the dopamine nuclei.
In rats, the dopaminergic system was removed, and the rats still liked certain tastes. This indicates wanting instead of liking: motivation to pursue a reward.
Nucleus accumbens: activated by wide range of motivationally relevant stimuli. Reinforcement of a desirable association.
DA neurons signal changes in information:
Reward prediction error (RPE): the actual outcome differs from what was expected.
Actor-critic models: the brain has 2 systems
- Critic: evaluation, are rewards better or worse than expected? ventral striatum (RPE)
- Actor: updates values of potential courses of action dorsal striatum
Damage to reward pathways:
- Motor: Parkinson’s, Huntington’s
- Psychiatric: schizophrenia, depression, ADHD
Pathological gamblers’ brains ‘learn’ from near-misses. Males 14-22 years old, prefrontal cortex not fully developed yet.
Salience can lead to dopaminergic increase.
Uncertainty: psychological state of having a lack of information.
Risk: decision has multiple potential outcomes with known probabilities
Brain regions risk taking:
[note: deze afbeelding uit het college is door de WorldSupporter redactie verwijderd wegens vermoedelijke inbreuk op het auteursrecht]
Ambiguity: probabilities of the outcomes cannot be known. OFC and PFC are involved.
Dual system: two separate processes
- Kahneman:
- System 1: fast, parallel, automatic, context-dependent
- System 2: slower, serial, controlled, evidence-based
Social stimuli are rewarding. How rewarding depends on the social relationship.
Two theories:
- Motivated by internal, reinforcing reward signals
- Required social cognition to recognize another individual’s needs
Parietal cortex: social cognition
mPFC: thinking about other people’s mental states
Game theory studies how decisions are made in complex situations.
- Prisoner’s dilemma
- Ultimatum game
- Trust game
Altruistic punishment: censuring people who violate social norms.
Currency signal: neurons tracking subjective value, regardless of category.
Drift-diffusion models: assume that decision making is a random drift from neural states towards thresholds for action.
Modality-indepenent value signals: ventromedial prefrontal cortex. Insensitivity to negative feedback after damage.
Heuristics: rules that allow people to simplify complex decision situations into something more manageable. Why do we need heuristics?
- Bounded rationality: organisms have finite computational resources
- Decisions are often made under time constraints
Anchoring heuristic: tendency of reference points to bias subsequent value judgements
Endowment effect: people require more money when selling something they own than they are willing to pay when buying identical good
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