Dual processing model - Bechara + Tversky & Kahnermann

Dual processing model

• System 1 thinking is automatic and intuitive; it is good for quick decisions and requires only a small amount of effort. System 1 thinking makes use of cognitive "shortcuts" called heuristics and is based on schemas. System 1 is also prone to errors and can result in impulsive actions

• System 2 is slower more rational thinking that consciously uses existing information to logically make a decision. System 2 thinking requires more effort and eliminates possibilities based on evidence

anchoring bias

this heuristic describes the tendency to rely too heavily on the first piece of info offered (the “anchor'“) when making decisions

Aim of tversky & khannerman

• to investigate the impact of anchoring biases and heuristics on decision making

method of tversky & khannerman

• Study used two conditions: high anchor condition and low anchor condition

• High anchor condition were given the math problem - 8×7×6×5×4×3×2×1

• Low anchor condition were given the math problem - 1×2×3×4×5×6×7×8

• after 5 seconds pp had to estimate the answer to the math problem they were given

• The difference between both groups was the high anchor of 8 and the low anchor of 1 as the solution to the math problems is the same

results of tversky & khannerman

• the pp in the high anchor condition estimated 2250 while the pp in the low anchor condition estimated 512

conclusion of tversky & khannerman

• In conclusion, anchoring bias affected decision-making because the pp with the low anchor estimated a lower solution to the math problem than the high anchor pp even though they both had the same math problem

tversky & khannerman eval

• very simple study which is easily replicated, increasing the reliability of the results

• low ecological validity as we don’t always have 5 seconds to estimate something

• independent samples design means there could be issues with pp variability

Aim of bechara

• to investigate the role of the vmPFC in decision making

method of bechara

• 17 healthy controls and 8 pp who had lesions to their ventromedial prefrontal cortex (vmPFC)

• pp had to do the Iowa gambling task

• pp had to choose from four decks of cards and did 100 trials

• pp would win or lose money based on card choice

• two of the decks had high initial reward with low long term success and other two decks had low initial reward with high long term success

results of bechara

• the pp with lesions in their vmPFC continued to choose the high initial reward, low long-term success decks even though they were eventually losing money

• the controls slowly began choosing the decks with low initial reward and high long-term success

Conclusion of bechara

• In conclusion, the lesions in the vmPFC affected decision-making because the pp with lesions were unable to stop making the bad decisions and kept taking the high initial reward and low long-term award while the controls were able to make the better decision to take from the other two decks

bechara link back

• this study used the DPM in the system 2 thinking as it tested if rational thinking and decision-making would be affected by lesions in pp vmPFC. The study found that rational thinking was affected as the pp with lesions to their vmPFC couldn’t make the rational decision to pick from the better cards.

bechara eval

• small sample size and some of sample had lesions to their vmPFC so not generalisable to whole population

• hard to understand procedure so pp could not understand how the game works, reducing internal validity

• can be applied to both system 1 and 2 thinking