Please enable JavaScript.

Coggle requires JavaScript to display documents.

Decision Making (Elements of simple perceptual decisions (Evidence, Pre…

- - - - monkey fixates, 2 targets appear either side of where he is looking and doesn't know which to respond to, 3rd light turns red/green to indicate which response is appropriate
      - Systematically varied probability of left/right response
      - LIP neurons showed a firing rate that correlated with EXPECTED GAIN or OUTCOME PROBABILITY
    - - Monkeys choose between 2 types of juice where A is preferred, in different ratios
      - Measure behavioural choices to establish subjective value
      - OFC neurons showed a U shaped pattern whereby the firing rate correlates with the subjective value of the chosen good
    - - Varied the menu between 3 choices and showed that the neural responses were invariant for changes in menu
      - Suggests an absolute value scale
    - - Human ventromedial PFC (=monkey OFC and medial PFC)
      - Scannedsubjects with fMRI while they made real purchasing decisions among items, before entering they had made WTP judgements for 80% chance
      - Showed activity in vmPFC correlated with the DV for that outcome
    - - Instrumental Extinction
      - Reinforcer devaluation
      - Object reversal learning
  - - - greater activity to unpredicted rewards
      - suppression to lack of predicted reward
      - no change to predicted rewards
  - - - Risk vs Ambiguous deck
      - Most people choose risk deck, and pay more to do so
      - Even though betting on either colour of ambiguous cannot both be disadvantageous
    - - Compared activity in risk and uncertainty
      - Activity in amygdala and OFC correlated positively with ambiguity
      - Activity in striatum correlated with expected reward (risk)
  - - - Damasion et al (2006)
        
        Sure (you win or you loose) vs gamble
        
        choose sure in win frames and gamble in loose frames
        
        amygdala correlated with behavioural tendencies
        
        OFC and vmPFC correlated with individual differences in susceptibility to the framing effect
    - - Bechara (1997)
        
        Choose between decks that yield high immediate gain but longer term loss, and vice versa
        
        anticipatory SCR and behavioural choices began to favour advantageous deck before conscious
        
        vmPFC lesioned patients didn't develop the anticipatory SCR
        
        suggests vmPFC may provide a somatic marker to non consciously guide decision processes
      - BUT Fellows & Forah (2005)
        
        vmPFC neurons were not impaired on task that avoids confounds with object reversal learning
- - - - Sensory evidence
    - - Decision variable
  - - - detect onset of coherent motion in RDM
      - MT: hit trials rose with rate of rise that was correlated with RT but not on false alarms
        
        Preliminary evidence
      - VIP: population responses less linked to motion onset but more stereotypical with the behavioural response
        
        DV or outcome of decision process
      - Rate of rise of firing rate reflected a race model
    - - Varied strength of motion signal from strong to weak
      - Neural responses in LIP covaried with final decision, mediated by motion coherence
      - Suggests LIP implements decision transformation from sensory representation to a DV used to direct motion
- - - - DVs evolve over time so may be distinguished from momentary evidence
      - Many real life decision are not tied to the time frame of sensory decisions