Chapter 12 Decision Making

the choice made after considering different alternatives

we should choose our actions based on what brings the greatest happiness to the greatest number of people

• measuring pleasure or pain in terms of 
• duration, intensity, propinquity, extent, certainty, purity, fecundity

desirability or value of a given course of action

• the predicted reward value of given option 
• models typically describe behaviours that would be expected of an idealised human being who makes perfectly rational choices to maximise utility

we have relative rather than absolute preferences

• inconsistent because of the uncertainty of outcome 
• risk aversion - smaller certain over larger uncertain 
• risk seeking - larger uncertain over smaller certain

individuals choose options based on how they're framed and thus choose inconsistently

people assign more value to a given item if they own the item and a lower value to the same item if they do not own it

• we assign disproportionally high values to immediate rewards and disproportionately low value to delayed rewards 
• marshmallow test
• delay discounting makes it easy for us to neglect long term consequences

animals make irrational decisions too

we focus on other people's internal characteristics (like personality) to explain their behaviour, but we focus on external situations (e.g. a hard day) to explain our behaviour

our brain contains two systems for decision making, one is evolutionarily older (well adapted for survival in the wild, less relevant now) and one is more recent

unconscious implicit processes info in parallel, high capacity, reaches conclusions rapidly but can be hard to explain why those conclusions were reached

conscious, explicit, deliberate to a logical conclusion, processes info sequentially, low capacity, reaches conclusions slowly

make sensible decisions between two rewards when they are both in the remote future, but are impulsive when comparing rearward now to a reward later

• 1. newer rational system should be active for decisions on future rewards
• 2. the older, intuitive system should be active for decisions that involve immediate rewards

• lateral frontal and parietal regions involved in rational system (regions active regardless of delay)
• medial limbic regions involved in intuitive system )regions more active when there is no delay between choices and reward)

**correlation isn't causation, inhibiting makes more likely doesn't say will

• sometimes lateral areas more active, sometimes medial more active
• interconnected regions working together as part of decision-making circuit and their relative activity might influence what decisions we make

we make decisions depending on if we stand to gain or lose from the risk (are we going to gain or lose money)

• risk seeking and reward value: central striatum, ventromedial PFC
• loss aversion and aversive stimuli: insula and amygdala

• responds differently to gain and loss frames its relative activity flips for gambles vs sure bets 
• not all people equally susceptible to framing effects, activity in vmPFC predicts resistance to the framing effect

• the value of a given option to a given individual in a particular context 
• can examine subjective value using the axiom of revealed preferences

• brain activity that tracks subjective value includes regions involved in assessing reward (medial prefrontal cortex, posterior cingulate gyrus, ventral striatum, medial prefrontal cortex, posterior cingulate gyrus)
• some people are impulsive, others are patient

• across species, orbitofrontal cortex seems to be a key brain area for representing subjective value
• convergence zone for assembling information about external stimuli internal states, current goals, and behaviours

• in people with high impulse control, dlPFC might inhibit the vmPFC response to enjoyable but unhealthy food 
• vmOFC activity tracks subjective reward value of food

tend to depend on sensory areas and lateral prefrontal cortices

• some decisions factor in our priorities, needs, drives, past experiences 
• tend to depend on ventral and medial prefrontal cortex

having multiple decision-making systems is adaptive because we can switch between them depending on our needs in the moment

• 1. clear cut external signals available - lateral prefrontal areas 
• 2. no external cues, need to consider past experiences - medial prefrontal/orbitofrontal cortex and ventral striatum
• 3. obvious threat - amygdala

• internally cued moral decision making - medial brain areas recruited for internally guided decisions
• rule-based or externally cued moral decision making - lateral brain areas recruited for externally guided decisions

switching between strategies is associated with activity in the lateral frontopolar cortex

• different strategies are available when gambling, maximise potential gain, minimise potential loss, or maximise the probability of winning at least some money (no matter the amount) 
• vlPFC and dmPFC involved in switching between strategies

• mathematical strategy: maximise chances of winning (posterior parietal cortex, dorsolateral prefrontal cortex)
• loss avoiding strategy: minimise size of potential losses (anterior insula)
• reward seeking strategy: maximise size of possible rewards (ventromedial prefrontal cortex)

• individual differences in decision making strategies (e.g. how susceptible different people are to framing effects) 
• people with long allele form of serotonin transporter gene show more interactions between amygdala and dmPFC and are better able to resist framing effects

• neurons have to be persuaded to change their pattern of activity 
• accomplished by neurotransmitter including serotonin, dopamine, norepinephrine, and more

this is why drugs affect decision making because they affect NT systems involved in decision making

• dopamine agonist, stimulates the release of dopamine in the synaptic terminals
• used for ADHD 
• increasing dopamine leads to increased than decreased impulsivity