Week 6 Lec 12: Context

Question 1

Describe the study by Iyengar & Lepper (2000) showing the effect of set size on behaviour.

Answer 1

Set up tasting booth for jams near the entrance of a busy grocery store (small selection vs large selection)
Larger set attracted more visitors but people who stopped in front of the small set were 10x more likely to buy a jar of jam

Question 2

What are some other examples of choice set size effects?

Answer 2

Lotteries, purchasing goods, taking loans, retirement plans

Question 3

Can you name the psychological explanation for the aversive effects of set size from different domains?

Answer 3

People dislike effort; more choice = more effort
- Size dependent search cost: cost in terms of time or effort required scanning the set
- Longer time and/or increased cognitive effort is associated with a certain level of disutility
- Cost benefit tradeoff in choice
People dislike being wrong; more choice = more errors possible

Question 4

Can you name the economic explanation for the aversive effects of set size from different domains?

Answer 4

Increased similarity between alternatives decreases ability to detect the marginal advantage of each option, making it harder to discriminate between options

Question 5

Can you name the neurobiological explanation for the aversive effects of set size from different domains?

Answer 5

Neuronal coding limitations may reduce choice discriminability

Question 6

Which axiom of rational choice theories is violated by the decoy effect?

Answer 6

Independence of irrelevant alternatives (adding same probability of third option to both choices doesnt change ordering of preferences)

Question 7

What is the attraction effect/asymmetric dominance?

Answer 7

A decoy that is inferior in all respects to one option but superior in only one aspect to another option will increase selection of the fully dominating option

Question 8

Give an example of the decoy effect.

Answer 8

Between a Tesla and a Prius, adding a Volt which is inferior to Prius in 2 dimensions and inferior to Tesla in only one dimension will shift preference towards the Prius
Alternative example: The decoy is asymmetrically dominated by the Tesla, which is better on both dimensions

Question 9

Can you describe a context effect from the domain of marketing actions and explain how it alters brain responses?

Answer 9

Plassmann (2008) assessed marketing actions and subjective utility and found that people claimed to prefer more expensive wine when it was the same wine
vmPFC and mOFC activity reflected price dependent value signals in the brain

Question 10

Can you name and describe the three neurobiological limitations of neurons that contribute to the neurobiological basis of context-dependency?

Answer 10

1. Non-negative (rectified): Firing rates are non-negative (input-output functions cannot represent parameters below a certain level)
2. Refractory periods (recharge): Biophysical limitation; neurons need to recharge and cannot exceed firing rate
3. Metabolically costly

Minimum and max firing rates limit the dynamic range of spiking activity, which limits the range of inputs that can be encoded

Question 11

What is the rate coding hypothesis?

Answer 11

Average activity (firing rate) is the primary info carrying characteristic of a neural spike train

Question 12

Can you describe the basic ideas behind the efficient coding hypothesis and range adaption?

Answer 12

Efficient coding hypothesis states that changes in firing rate code for change in behavioural parameter
range adaptation (normalization) states that the range of neural firing rates should match the range of values in the decision environment
Assumptions of range adaptation
- Range of neural firing rate is constant across different behavioural value conditions
- Account for the local spread of values (delta V), assign the minimum to lowest firing rate, highest to maximum