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Anticipation and choice heuristics in the dynamic consumption of pain relief.

Story GW, Vlaev I, Dayan P, Seymour B, Darzi A, Dolan RJ - PLoS Comput. Biol. (2015)

Bottom Line: Participants exhibited three characteristic behaviors: saving relief until the end, spreading relief across time, and early spending, of which the last was markedly less prominent.The likelihood that behavior was heuristic rather than normative is suggested by the weak correspondence between one-off and dynamic choices.We show that the consumption choices are consistent with a combination of simple heuristics involving early-spending, spreading or saving of relief until the end, with subjects predominantly exhibiting the last two.

View Article: PubMed Central - PubMed

Affiliation: Centre for Health Policy, Institute of Global Health Innovation, Imperial College London, London, United Kingdom; Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom.

ABSTRACT
Humans frequently need to allocate resources across multiple time-steps. Economic theory proposes that subjects do so according to a stable set of intertemporal preferences, but the computational demands of such decisions encourage the use of formally less competent heuristics. Few empirical studies have examined dynamic resource allocation decisions systematically. Here we conducted an experiment involving the dynamic consumption over approximately 15 minutes of a limited budget of relief from moderately painful stimuli. We had previously elicited the participants' time preferences for the same painful stimuli in one-off choices, allowing us to assess self-consistency. Participants exhibited three characteristic behaviors: saving relief until the end, spreading relief across time, and early spending, of which the last was markedly less prominent. The likelihood that behavior was heuristic rather than normative is suggested by the weak correspondence between one-off and dynamic choices. We show that the consumption choices are consistent with a combination of simple heuristics involving early-spending, spreading or saving of relief until the end, with subjects predominantly exhibiting the last two.

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Related in: MedlinePlus

Trial structure of the experiment.Participants entered an experimental run of 60 trials, on which they could expect to receive mildly painful electric shock stimuli on each trial, referred to as painful episodes. By default participants could expect to receive a five second stimulus with 14 brief shocks on each trial, however they were provided with a budget of relief at the outset of the experiment, 2400 “milligrammes” (mg) in total. Each 10mg of relief consumed reduced the expected number of shocks in the stimulus train by one, and was hence insufficient to relieve all the shocks in the session. At the start of each trial a screen indicated the number of remaining trials and the remaining supply of relief. Participants then had the opportunity to indicate how much relief they wished to consume on that trial, up to a maximum of 120mg. The relief was then effective on the immediately subsequent painful episode.
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pcbi.1004030.g001: Trial structure of the experiment.Participants entered an experimental run of 60 trials, on which they could expect to receive mildly painful electric shock stimuli on each trial, referred to as painful episodes. By default participants could expect to receive a five second stimulus with 14 brief shocks on each trial, however they were provided with a budget of relief at the outset of the experiment, 2400 “milligrammes” (mg) in total. Each 10mg of relief consumed reduced the expected number of shocks in the stimulus train by one, and was hence insufficient to relieve all the shocks in the session. At the start of each trial a screen indicated the number of remaining trials and the remaining supply of relief. Participants then had the opportunity to indicate how much relief they wished to consume on that trial, up to a maximum of 120mg. The relief was then effective on the immediately subsequent painful episode.

Mentions: Fig. 1 illustrates the experimental protocol. On each trial, subjects received a number of shocks drawn from a Poisson distribution. Without pain relief, the mean of this distribution was 14 shocks; for every 1mg of relief the subjects spent on a trial, the mean decreased by 0.1 shocks. Subjects were allowed to spend a maximum of 120mg of relief on a trial; this reduced the mean number of shocks to 2, a level termed the ‘baseline pain’. Subjects had to spend within a total budget of 2400mg. Before making their choice, participants were informed of the total relief capital remaining, the number of trials remaining and the mean remaining relief per trial.


Anticipation and choice heuristics in the dynamic consumption of pain relief.

Story GW, Vlaev I, Dayan P, Seymour B, Darzi A, Dolan RJ - PLoS Comput. Biol. (2015)

Trial structure of the experiment.Participants entered an experimental run of 60 trials, on which they could expect to receive mildly painful electric shock stimuli on each trial, referred to as painful episodes. By default participants could expect to receive a five second stimulus with 14 brief shocks on each trial, however they were provided with a budget of relief at the outset of the experiment, 2400 “milligrammes” (mg) in total. Each 10mg of relief consumed reduced the expected number of shocks in the stimulus train by one, and was hence insufficient to relieve all the shocks in the session. At the start of each trial a screen indicated the number of remaining trials and the remaining supply of relief. Participants then had the opportunity to indicate how much relief they wished to consume on that trial, up to a maximum of 120mg. The relief was then effective on the immediately subsequent painful episode.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4368544&req=5

pcbi.1004030.g001: Trial structure of the experiment.Participants entered an experimental run of 60 trials, on which they could expect to receive mildly painful electric shock stimuli on each trial, referred to as painful episodes. By default participants could expect to receive a five second stimulus with 14 brief shocks on each trial, however they were provided with a budget of relief at the outset of the experiment, 2400 “milligrammes” (mg) in total. Each 10mg of relief consumed reduced the expected number of shocks in the stimulus train by one, and was hence insufficient to relieve all the shocks in the session. At the start of each trial a screen indicated the number of remaining trials and the remaining supply of relief. Participants then had the opportunity to indicate how much relief they wished to consume on that trial, up to a maximum of 120mg. The relief was then effective on the immediately subsequent painful episode.
Mentions: Fig. 1 illustrates the experimental protocol. On each trial, subjects received a number of shocks drawn from a Poisson distribution. Without pain relief, the mean of this distribution was 14 shocks; for every 1mg of relief the subjects spent on a trial, the mean decreased by 0.1 shocks. Subjects were allowed to spend a maximum of 120mg of relief on a trial; this reduced the mean number of shocks to 2, a level termed the ‘baseline pain’. Subjects had to spend within a total budget of 2400mg. Before making their choice, participants were informed of the total relief capital remaining, the number of trials remaining and the mean remaining relief per trial.

Bottom Line: Participants exhibited three characteristic behaviors: saving relief until the end, spreading relief across time, and early spending, of which the last was markedly less prominent.The likelihood that behavior was heuristic rather than normative is suggested by the weak correspondence between one-off and dynamic choices.We show that the consumption choices are consistent with a combination of simple heuristics involving early-spending, spreading or saving of relief until the end, with subjects predominantly exhibiting the last two.

View Article: PubMed Central - PubMed

Affiliation: Centre for Health Policy, Institute of Global Health Innovation, Imperial College London, London, United Kingdom; Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom.

ABSTRACT
Humans frequently need to allocate resources across multiple time-steps. Economic theory proposes that subjects do so according to a stable set of intertemporal preferences, but the computational demands of such decisions encourage the use of formally less competent heuristics. Few empirical studies have examined dynamic resource allocation decisions systematically. Here we conducted an experiment involving the dynamic consumption over approximately 15 minutes of a limited budget of relief from moderately painful stimuli. We had previously elicited the participants' time preferences for the same painful stimuli in one-off choices, allowing us to assess self-consistency. Participants exhibited three characteristic behaviors: saving relief until the end, spreading relief across time, and early spending, of which the last was markedly less prominent. The likelihood that behavior was heuristic rather than normative is suggested by the weak correspondence between one-off and dynamic choices. We show that the consumption choices are consistent with a combination of simple heuristics involving early-spending, spreading or saving of relief until the end, with subjects predominantly exhibiting the last two.

Show MeSH
Related in: MedlinePlus