Delayed reinforcement and self control Flashcards
Wilkonson et al (1992)
Rat subjects magazine trained on a FR1 schedule, but reinforcers preceded by a delay of 0,4,8,18s. The control group had no reinforcers. There was also an additional lever which if pressed during the delay, reset the time. The no food group did not learn to lever press (had no reinforcement). The fastest group to learn was the group with no delay, and with increasing delays, the responses decreased. Hence, there is a preference for non-delayed reinforcement over delayed reinforcement.
Delay seems to devalue reinforcement
1) Response acquisition is slower with increasing delay
2) Preference for the sooner option
3) Adding a delay to reinforcement decreases the rate of responding
Mazur’s delay-titration procedure
Choice between smaller sooner and larger later reinforcer. Hold smaller sooner delay constant, whilst adjusting delay to the larger later reinforcer. Adjust until responding is the same on each choice = indifference point.
=Find out how much delay we have to add to the larger later reinforcer to make it the same value as the smaller sooner reinforcer.
Johnson & Bickel (2002)
Used a titration procedure asking people to choose between two amounts of money. Reduced the larger later reinforcer delay until it was at equal value to the smaller sooner - indifference point.
Longer adjusting delays = means there is more self control.
Shorter adjusting delays = means there is less self control.
Charlton & Fatino (2008)
Same task; different hypothetical commodities matched for dollar value - money, books, DVD, music, food. Found that all commodities followed the same hyperbolic decay curve of discounting, but that money had the steepest curve. I.e, money seems to retain is value to a larger extent that other commodities with added delay to reinforcement – it is devalued at a slower rate.
Odum (2011)
Investigated the effects of delay to reinforcement on: money, heroin, cigarrettes and food. Found that money holds its value much better than any other commodity (AUC is always larger).
He also found that if you are a person whom adding a delay devalues the subjective value of money a lot, adding delay to any other commodity will also decrease its subjective value to a greater extent.
Delay discounting: state or trait
State: largely reliant on experimental conditions
Trait: individual differences that we call personality (things we cant change) – impulsivity or self control
Bickel et al (1999)
Smokers vs non-smokers delay discounting. Those who are current smokers delay money (+cigarrettes) to a greater extent with increasing delay - i.e., smaller AUC than non-smokers.
Laude, Beckmann, Daniels & Zentall (2013)
Gambling prone pigeons - measured pigeons impulsivity by a delay discounting task and then got them to do a gambling task (in two groups: high and low impulsivity).
1) key 1. Mean = 2 pellets, but could get 10 = VI
2) key 2. Mean = 3 pellets, always get 3. FI
Responses were graphed as %suboptimal choice vs sessions. Anything less than 50% means they are choosing the non-gambling task more than the gambling task, and vice versa.
Both groups relatively the same for the first 15 session. But following this, the high impulsivity group were choosing to gamble on a high % of choices - whilst the low impulsivity group stayed around 50%.
* There is an association between the extent to which you discount reinforcers with increasing delay, and the likelihood of engaging in risky, maladaptive, compulsive behaviour.
Weller, Cook, Avsar & Cox (2008)
Obese men and women vs healthy weight men and women with hypothetical delay discounting task to money. Found that obese women had less self control, and that delay devalued the money to a larger extent than the healthy weight women, shown by a smaller AUC. However, they did not take into account income - an environmental factor that impacts reward. Those with a lower income discount rewards more rapidly and are more impulsive than those with a higher income.
–> Hence the extent to which delay devalues reward depends on both personality and environmental factors.
Johnson & Bickel (2002)
Investigated magnitude and money. Rewards that are smaller tend to lose their value more rapidly than those rewards that are larger. Hence, the magnitude of the reward will dictate how steeply the reward is discounted with delay.
Dixon, Jacobs & Sanders (2006)
Investigated the effect of setting on discounting. Used pathological gamblers and got them to carry out a delay discounting task in a number of different settings: park, coffee shop, off bet gambling facility. They found that the subjects were more impulsive, and discounted reward to a greater extent (smaller AUC and faster rate of decay) in the off-bet gambling facility compared to the other settings. Hence, environmental factors play an important part in delay discounting.
Green, Myerson, Lichtman, Rosen & Fry (1996)
Investigated the effect on income (high and low) on delay discounting to two values of money - $1000, $10000.
1) Found the effect of magnitude- that the AUC is larger, and that the larger value of money is losing its value at a lower rate.
2) Found that the upper income group devalued the reinforcers to a lesser extent with increasing delay (larger AUC) compared to those in the lower income group.
