In two minds: The neuroscience of decision-making Deborah Talmi, School of Psychological Sciences, University of Manchester

Outline Why neuroscience? Two systes for decision making –Examples from moral and economic decisions How does the implicit system influence decision-making? –Empirical examples

Proscriptive models offer yardsticks for good decisions… –Serve the greater society –Rational (e.g. preferences are consistent with each other) –Maximise the hedonic experience (happiness) associated with an outcome Descriptive models: How do people actually make decisions? –Empirical answers Proscriptive and descriptive models > >

UnconsciousConscious ImplicitExplicit AutomaticControlled Low effortHigh effort RapidSlow Holistic, perceptualAnalytic, reflective Evolutionarily oldEvolutionarily recent NonverbalLinked to language AssociativeRule based Domain specificDomain general ContextualizedAbstract Independent of general intelligenceLinked to general intelligence Independent of working memoryLimited by working memory capacity ImplicitExplicit The dual processing framework

Moral decisions The trolley problem: Implicit and explicit preferences The two systems are implemented in separate brain regions Patients with damage to frontal brain regions compared to brain damaged and healthy controls Patients made more ‘explicitly rational’ decisions

Endowment: $20 of play money Invest (pay $1) or not (keep 1$)? Lose $1Win $2.50 Patients won 25$ Controls won 20$ Economic decisions

Pavlovian control –Attraction to stimuli previously associated with reward Habitual control –Continue previously rewarded behaviour even when it is no longer rewarding Goal-directed control –Explicit representation of the link between the action and the outcome Control of behaviour – animal decision Implicit Explicit

Computations of the implicit system give rise to feelings and intuitions –Is the current situation better or worse than expected? The implicit system and emotions Early TrainingLate Training

When the environment is complex, computation in the implicit system can improve decisions The implicit system can help decisions % choosing the objectively better car EasyComplex

Implicit computations are associative, making them vulnerable to contextual biases This can get in the way of making optimal decisions % choice of an unhealthy snack The implicit system can hinder decisions

Neuroscience research improves our understanding of the way people make decisions The dual process view explains why we can be ‘in two minds’ about a choice Implicit computations give rise to emotions The properties of implicit computations explain why emotions seem to sometimes help and sometimes hinder us from making optimal decisions Summary: Deciding well