hi my name is Heather Francisco and I'm a board certified behavior analyst with
Brett DiNovi & Associates and I will be discussing the topic of
discounting discounting occurs when the subjective value of an outcome changes
because it's delivery is delayed or uncertain discounting is when rewards
lose their value this video will focus on delay discounting the rate of delay
discounting is how fast a reward loses its value over time discounting has a
significant impact on choice making for example a nicotine deprived smoker may
highly value a cigarette and would be motivated to get one in the next six
hours in contrast that same smoker would assign no value and do little to obtain
a cigarette available in six months from now when making a decision Juan may or
may not forego small immediate rewards in order to obtain larger rewards in the
future this can manifest in many of our decisions one might study for his exam
that is next Friday or go out with his friends tonight one might try to obtain
a healthy weight by eating foods low in calories or eat a piece of chocolate
cake at a friend's birthday party another might save a certain amount of
money to buy a car in six months or buy jewelry for a dance that is tomorrow
people have a tendency to discount how valuable a reward is when that reward is
increasingly further in the future behavior analysts described impulsive
'ti as the likelihood that one would choose a smaller sooner reward over the
larger later reward inversely self-control is the likelihood that one
would wait for the larger later reward when a person demonstrates that they
have high self-control they are considered shallow discounters and when
a person demonstrates they are impulsive they are considered steep discounters
the Stanford marshmallow experiment was a series of well-known studies on
delayed gratification in the late 1960s and early 1970s led by psychologist
Walter Mitchell a child has offered a choice between one small reward provided
immediately or two small rewards contingent on waiting for a short period
of time for approximately 15 minutes the tester left the room and the
participants waited for them to return the researchers then observed
participants behavior during that 15 minutes and
noted which participants could wait for the delayed reward of two treats the
reward was sometimes a marshmallow but often a cookie or pretzel depending on
the participants preference the study sought to determine variability and
choice making and self-control among preschoolers it also had implications
for measuring delay discounting delay discounting procedures are about finding
the point at which two rewards one relatively immediate and one delayed
have approximately the same value this is known as the indifference point in
assessing how delay affects the value of outcomes with humans researchers
commonly ask people to make a series of choices between hypothetical options
rather than giving them a consequences associated with each choice for example
rattlin Ranieri and cross in 1991 asked college students to choose between $1000
available today and $1,000 available in a month the amount of the immediate
option decreased across trials until it reached $1 then it increased back up to
$1,000 the indifference point was the average amount at which the participants
switched the preference for the small sooner reward or the later larger reward
so for example a participant would prefer $1000 today over $1000 in a month
but then at about nine hundred and sixty dollars today might switch to choosing
the delayed option of $1000 through the rest of the trials as the immediate
amount continued to decrease when the immediate amount then increased across
trials the participant would initially prefer the delayed 1000 but then at
perhaps at nine hundred and forty would switch to choosing the immediate amount
again in this particular example the indifference point would be on average
nine hundred and fifty dollars in general the indifference points
decreased as the delay to the larger amount increase this is the empirical
demonstration of delayed discounting the value of money is degraded
systematically as the money becomes a more remote or further in the future
moszer in 1987 evaluated several different possible quantitative models
to describe the indifference points as a function of delay and determined that
the following equation provided the best the hyperbolic equation states that the
present value of a reward known as V is equal to the amount or magnitude of the
reward known as M or a divided by the delay of the reward D the numeral 1
appears in the denominator of the equation to prevent present value from
approaching infinity as the delay approaches 0 the delay D is then
multiplied by a scaling factor K which describes how much value is affected by
delay if K is relatively large then the effect of the delay on degrading value
is bigger than if K is small as the empirically derived discounting K value
increases the discounted value V decreases more quickly as a function of
the delay in other words the larger the degree of discounting the quicker the
value decreases over time the hyperbolic equation can be broken down as follows V
equals a divided by 1 plus K divided by D V equals the subjective value a or M
is the amount or magnitude of the reward K is the sensitivity to change in delay
or the value of discounting and D is the length of the delay
according to Kaplan in 2016 one efficient approach to obtaining a human
subjects rate of delay discounting is via the 21 and 27 item monetary choice
questionnaire this consists of choice tasks that assess preference between
small immediate and large delays monetary outcomes
unfortunately the scoring procedures for the questionnaire are rather complex
which may serve as a barrier to their use this report details a freely
available Excel based spreadsheet tool that automatically scores momentary
choice questionnaires and response sets one participants scored a zero it
suggests that they would take the monetary award as opposed to the larger
later reward after the specified delay delay lengths varied per trial when
participants scored at one it suggests that they would wait for the specified
delay for the larger monetary reward more zeros and less ones indicates deep
discounting and less zeros and more ones indicate shallow delay
discounting more to come on discounting stay tuned
references are cited beneath the video feel free to post questions or comments
below
you