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Papers by forest baker

Research paper thumbnail of Delay Discounting in Current and Never-Before Cigarette Smokers: Similarities and Differences Across Commodity, Sign, and Magnitude

Journal of Abnormal Psychology, 2003

Research has found that nicotine-dependent individuals delay discount monetary gains at a higher ... more Research has found that nicotine-dependent individuals delay discount monetary gains at a higher rate than matched controls. Delay discount rates, however, have also been found to vary across within-subject variables such as the magnitude of the outcome (e.g., 10or10 or 10or1,000), whether the outcome constitutes a gain or a loss, and the commodity being evaluated (e.g., money or health). The present study comprehensively investigated the differences in delay discounting between current and never-before cigarette smokers and across these within-subject variables. Both groups exhibited a magnitude, sign, and commodity effect. Current smokers' delay discount rates for monetary outcomes, however, were higher than never-before smokers across all magnitudes and both signs. This trend was also found for delayed health outcomes, but failed to reach significance.

Research paper thumbnail of Optimism, Financial Literacy and Participation

Research paper thumbnail of Optimism, Financial Literacy and Participation

SSRN Electronic Journal, 2000

Research paper thumbnail of Delay discounting differs between current and never-smokers across commodities, sign, and magnitudes

Research paper thumbnail of Learning by pigeons playing against tit-for-tat in an operant prisoner's dilemma.

Each of four pigeons was exposed to a single random-ratio schedule of reinforcement in which the ... more Each of four pigeons was exposed to a single random-ratio schedule of reinforcement in which the probability of reinforcement for a peck on either of two keys was 1/25. Reinforcer amounts were determined by an iterated prisoner's dilemma (IPD) matrix in which the "other player" (a computer) played tit-for-tat. One key served as the cooperation (C) key; the other served as the defection (D) key. If a peck was scheduled to be reinforced and the D-key was pecked, the immediate reinforcer of that peck was always higher than it would have been had the C-key been pecked. However, if the C-key was pecked and the following peck was scheduled to be reinforced, reinforcement amount for pecks on either key were higher than they would have been if the previous peck had been on the D-key. Although immediate reinforcement was always higher for D-pecks, the overall reinforcement rate increased linearly with the proportion of C-pecks. C-pecks thus constituted a form of self-control. All the pigeons initially defected with this procedure. However, when feedback signals were introduced that indicated which key had last been pecked, cooperation (relative rate of C-pecks)--hence, self-control--increased for all the pigeons.

Research paper thumbnail of Probability of reciprocation in repeated prisoner's dilemma games

Journal of Behavioral Decision Making, 2001

Both social cooperation and self!control require reciprocation[ In social coop! eration situation... more Both social cooperation and self!control require reciprocation[ In social coop! eration situations a single person|s cooperative act\ if not reciprocated by others\ would be unreinforced both immediately and in the long term[ Similarly\ a single act of self!control "refusing a single cigarette\ for example#\ if not followed up by other such acts\ would also be unreinforced immediately and in the long term[ The present experiments varied probability of reciprocation in a prisoner|s dilemma! like game that could resemble a social cooperation or a self!control situation[ Participants earned points by playing against a computer[ The computer o}ered the participant a choice between 4 or 5 points "{cooperation| by the computer# or between 0 or 1 points "{defection| by the computer#[ The participant|s choice of the lesser alternative "{cooperation|# or the greater alternative "{defection|# on the current trial led\ respectively\ to cooperation or defection by the computer on the next trial with a probability "probability of reciprocation\ PR# which could vary[ When PR was greater than 52)\ consistent cooperation maximized the par! ticipant|s earnings[ When PR was less than 52)\ defection maximized earnings[ Three conditions were studied] PR signaled by spinners^PR unsignaled^PR unsig! naled with participants believing that they were playing with another person\ not the computer[ With PR 099) "{tit!for!tat|# and PR 49)\ the modal participant maximized earnings under all three conditions[ With PR 64)\ par! ticipants maximized earnings only when PR was signaled[ These results indicate that di}erences between people|s tendency to cooperate with other people "social cooperation# and their tendency to cooperate with their own future interests "self! control# may lie in di}erences in subjective PR[ public radio station and deposit their litter in the trash can\ for examples\ only if they believe that others will do the same[ If other people fail to cooperate "if they defect#\ a single individual|s cooperative act loses its function "the public radio station goes o} the air\ the streets are dirty# and is wasted[ Reciprocation is similarly important in self!control situations[ The immediate bene_ts of drinking\ overeating\ and smoking\ for example\ are often greater than those of their alternatives * refusing the drink\ the rich dessert\ the cigarette[ To attain the lon`!term bene_ts of sobriety\ diet\ and health one has to put together a long series of such refusals[ A heavy smoker who\ with great e}ort\ gives up smoking today\ and then resumes smoking tomorrow\ will have wasted the e}ort of not smoking today[ An act of self!control is thus\ in a sense\ an act of cooperation with one|s long!term interestsâ n impulsive act is a defection from those interests "Ainslie\ 0881#[ For self!control to succeed it is important that today|s act of self!control be reciprocated by tomorrow|s[ In other words\ while social cooperation requires reciprocation between individuals over social space\ self!control requires reciprocation by an individual over time[ All three of the present experiments varied the probability of reciprocation of cooperation and defection by individual subjects playing a prisoner|s dilemma!like game with a computer[ The _rst two experiments resembled self!control situations in the sense that choice of a larger reward on the current trial could lead to lower overall reward[ The third experiment resembled a social!cooperation situationŝ ubjects believed they were playing the prisoner|s dilemma game against another subject[ The prisoner|s dilemma game "Axelrod\ 0873^Rapoport and Chammah\ 0854# epitomizes a common social dilemma * a con~ict between the interests of an individual and those of a group containing the individual[ Exhibit 0"a# is a contingency matrix of a typical two!player prisoner|s dilemma game[ The numbers in the matrix represent amounts of reward "in points convertible to dollars\ for example# for two players "A and B# contingent on each player|s choice between two alternatives] cooperate "C# or Exhibit 0[ "a# Contingency matrix of a typical two!player prisoner|s dilemma game[ The numbers in the matrix represent amounts of reward for two players "A and B# contingent on each player|s choice between two alternatives] cooperate "C# or defect "D#[ If both players cooperate\ each gets 4 points^if both defect\ each gets 1 points[ If one player cooperates while the other defects\ the cooperator gets 0 point while the defector gets 5 points[ "b# Repeated prisoner|s dilemma game from the viewpoint of Player A[ Player B|s choice "C or D# is represented by the two vertical lines[ If Player B cooperates "left vertical line# Player A earns 5 points by defecting and 4 by cooperatingî f Player B defects "right vertical line# Player A earns 1 points by defecting and 0 by cooperating[ The dashed line shows Player A|s average return\ when playing against tit!for!tat in repeated games\ as a function of Player A|s percent defections "the left vertical line representing no defections and all cooperations\ the right vertical line\ the reverse# PR 099)\ p 9[954[ Exhibit 3 shows the distributions of cooperation choices by participants during the last 19 trials for the three PR conditions^the distributions are heavily skewed with modes towards the extremes "9\ 19\ 19# for the 49)\ 64)\ 099) conditions[

Research paper thumbnail of Teaching and learning in a probabilistic prisoner's dilemma

Behavioural Processes, 2002

The prisoner's dilemma is much studied in social psychology and decision-making because it models... more The prisoner's dilemma is much studied in social psychology and decision-making because it models many real-world conflicts. In everyday terms, the choice to 'cooperate' (maximize reward for the group) or 'defect' (maximize reward for the individual) is often attributed to altruistic or selfish motives. Alternatively, behavior during a dilemma may be understood as a function of reinforcement and punishment. Human participants played a prisoner's-dilemma-type game (for points exchangeable for money) with a computer that employed either a teaching strategy (a probabilistic version of tit-for-tat), in which the computer reinforced or punished participants' cooperation or defection, or a learning strategy (a probabilistic version of Pavlov), in which the computer's responses were reinforced and punished by participants' cooperation and defection. Participants learned to cooperate against both computer strategies. However, in a second experiment which varied the context of the game, they learned to cooperate only against one or other strategy; participants did not learn to cooperate against tit-for-tat when they believed that they were playing against another person; participants did not learn to cooperate against Pavlov when the computer's cooperation probability was signaled by a spinner. The results are consistent with the notion that people are biased not only to cooperate or defect on individual social choices, but also to employ one or other strategy of interaction in a pattern across social choices.

Research paper thumbnail of Probability of reciprocation in repeated prisoner's dilemma games

Journal of Behavioral Decision Making, 2001

Both social cooperation and self!control require reciprocation[ In social coop! eration situation... more Both social cooperation and self!control require reciprocation[ In social coop! eration situations a single person|s cooperative act\ if not reciprocated by others\ would be unreinforced both immediately and in the long term[ Similarly\ a single act of self!control "refusing a single cigarette\ for example#\ if not followed up by other such acts\ would also be unreinforced immediately and in the long term[ The present experiments varied probability of reciprocation in a prisoner|s dilemma! like game that could resemble a social cooperation or a self!control situation[ Participants earned points by playing against a computer[ The computer o}ered the participant a choice between 4 or 5 points "{cooperation| by the computer# or between 0 or 1 points "{defection| by the computer#[ The participant|s choice of the lesser alternative "{cooperation|# or the greater alternative "{defection|# on the current trial led\ respectively\ to cooperation or defection by the computer on the next trial with a probability "probability of reciprocation\ PR# which could vary[ When PR was greater than 52)\ consistent cooperation maximized the par! ticipant|s earnings[ When PR was less than 52)\ defection maximized earnings[ Three conditions were studied] PR signaled by spinners^PR unsignaled^PR unsig! naled with participants believing that they were playing with another person\ not the computer[ With PR 099) "{tit!for!tat|# and PR 49)\ the modal participant maximized earnings under all three conditions[ With PR 64)\ par! ticipants maximized earnings only when PR was signaled[ These results indicate that di}erences between people|s tendency to cooperate with other people "social cooperation# and their tendency to cooperate with their own future interests "self! control# may lie in di}erences in subjective PR[ public radio station and deposit their litter in the trash can\ for examples\ only if they believe that others will do the same[ If other people fail to cooperate "if they defect#\ a single individual|s cooperative act loses its function "the public radio station goes o} the air\ the streets are dirty# and is wasted[ Reciprocation is similarly important in self!control situations[ The immediate bene_ts of drinking\ overeating\ and smoking\ for example\ are often greater than those of their alternatives * refusing the drink\ the rich dessert\ the cigarette[ To attain the lon`!term bene_ts of sobriety\ diet\ and health one has to put together a long series of such refusals[ A heavy smoker who\ with great e}ort\ gives up smoking today\ and then resumes smoking tomorrow\ will have wasted the e}ort of not smoking today[ An act of self!control is thus\ in a sense\ an act of cooperation with one|s long!term interestsâ n impulsive act is a defection from those interests "Ainslie\ 0881#[ For self!control to succeed it is important that today|s act of self!control be reciprocated by tomorrow|s[ In other words\ while social cooperation requires reciprocation between individuals over social space\ self!control requires reciprocation by an individual over time[ All three of the present experiments varied the probability of reciprocation of cooperation and defection by individual subjects playing a prisoner|s dilemma!like game with a computer[ The _rst two experiments resembled self!control situations in the sense that choice of a larger reward on the current trial could lead to lower overall reward[ The third experiment resembled a social!cooperation situationŝ ubjects believed they were playing the prisoner|s dilemma game against another subject[ The prisoner|s dilemma game "Axelrod\ 0873^Rapoport and Chammah\ 0854# epitomizes a common social dilemma * a con~ict between the interests of an individual and those of a group containing the individual[ Exhibit 0"a# is a contingency matrix of a typical two!player prisoner|s dilemma game[ The numbers in the matrix represent amounts of reward "in points convertible to dollars\ for example# for two players "A and B# contingent on each player|s choice between two alternatives] cooperate "C# or Exhibit 0[ "a# Contingency matrix of a typical two!player prisoner|s dilemma game[ The numbers in the matrix represent amounts of reward for two players "A and B# contingent on each player|s choice between two alternatives] cooperate "C# or defect "D#[ If both players cooperate\ each gets 4 points^if both defect\ each gets 1 points[ If one player cooperates while the other defects\ the cooperator gets 0 point while the defector gets 5 points[ "b# Repeated prisoner|s dilemma game from the viewpoint of Player A[ Player B|s choice "C or D# is represented by the two vertical lines[ If Player B cooperates "left vertical line# Player A earns 5 points by defecting and 4 by cooperatingî f Player B defects "right vertical line# Player A earns 1 points by defecting and 0 by cooperating[ The dashed line shows Player A|s average return\ when playing against tit!for!tat in repeated games\ as a function of Player A|s percent defections "the left vertical line representing no defections and all cooperations\ the right vertical line\ the reverse# PR 099)\ p 9[954[ Exhibit 3 shows the distributions of cooperation choices by participants during the last 19 trials for the three PR conditions^the distributions are heavily skewed with modes towards the extremes "9\ 19\ 19# for the 49)\ 64)\ 099) conditions[

Research paper thumbnail of Reinforcement and punishment in the prisoner's dilemma game

Psychology of Learning and Motivation, 2000

... Reinforcement and punishment in the prisoner's dilemma game. ... The prisone... more ... Reinforcement and punishment in the prisoner's dilemma game. ... The prisoner's dilemma is important because it mirrors many dilemmas of everyday life. The name, "prisoner'sdilemma," comes from the common occurrence wherein ...

Research paper thumbnail of Learning by pigeons playing against tit-for-tat in an operant prisoner’s dilemma

Learning & Behavior, 2003

Each of four pigeons was exposed to a single random-ratio schedule of reinforcement in which the ... more Each of four pigeons was exposed to a single random-ratio schedule of reinforcement in which the probability of reinforcement for a peck on either of two keys was 1/25. Reinforcer amounts were determined by an iterated prisoner’s dilemma (IPD) matrix in which the “other player” (a computer) playedtit-for-tat. One key served as thecooperation(C) key; the other served as thedefection(D) key. If a peck was scheduled to be reinforced and the D-key was pecked, the immediate reinforcer of that peck was always higher than it would have been had the C-key been pecked. However, if the C-key was pecked and thefollowing peck was scheduled to be reinforced, reinforcement amount for pecks on either key were higher than they would have been if the previous peck had been on the D-key. Although immediate reinforcement was always higher for D-pecks, the overall reinforcement rate increased linearly with the proportion of C-pecks. C-pecks thus constituted a form of self-control. All the pigeons initially defected with this procedure. However, when feedback signals were introduced that indicated which key had last been pecked,cooperation (relative rate of C-pecks)—hence, self-control—increased for all the pigeons.

Research paper thumbnail of Self-control by pigeons in the prisoner's dilemma

Psychonomic Bulletin & Review, 2002

Pigeons played a repeated prisoner's dilemma game against a computer that reflected their choices... more Pigeons played a repeated prisoner's dilemma game against a computer that reflected their choices: If a pigeon cooperated on trial n, the computer cooperated on trial n + 1; if the pigeon defected on trial n, the computer defected on trial n + 1. Cooperation thus maximized reinforcement in the long term, but defection was worth more on the current trial. Under these circumstances, pigeons normally defect. However, when a signal correlated with the pigeon's previous choice immediately followed each current trial choice, some pigeons learned to cooperate. Furthermore, cooperation was higher when trials were close together in time than when they were separated by long intertrial intervals.

Research paper thumbnail of Delay Discounting in Current and Never-Before Cigarette Smokers: Similarities and Differences Across Commodity, Sign, and Magnitude

Journal of Abnormal Psychology, 2003

Research has found that nicotine-dependent individuals delay discount monetary gains at a higher ... more Research has found that nicotine-dependent individuals delay discount monetary gains at a higher rate than matched controls. Delay discount rates, however, have also been found to vary across within-subject variables such as the magnitude of the outcome (e.g., 10or10 or 10or1,000), whether the outcome constitutes a gain or a loss, and the commodity being evaluated (e.g., money or health). The present study comprehensively investigated the differences in delay discounting between current and never-before cigarette smokers and across these within-subject variables. Both groups exhibited a magnitude, sign, and commodity effect. Current smokers' delay discount rates for monetary outcomes, however, were higher than never-before smokers across all magnitudes and both signs. This trend was also found for delayed health outcomes, but failed to reach significance.

Research paper thumbnail of Decision-making in state lotteries: Half now or all of it later

Psychonomic Bulletin & Review, 2003

Many state lotteries offer players a choice between receiving roughly half of the jackpot immedia... more Many state lotteries offer players a choice between receiving roughly half of the jackpot immediately and receiving the entire jackpot over 25 annual payments. This requires players to make a decision that involves uncertainty, delay, and large amounts of real money. Archival data on lottery players’ jackpot payment decisions were collected from seven state and three multistate lotteries. Players’ jackpot payment preferences were assessed at the time of ticket purchase and after winning a jackpot. Preference for the annuity payment option significantly decreased as jackpot size increased, both at the time of ticket purchase and after winning. Furthermore, a significant proportion of winners who selected the annuity payment option at ticket purchase switched to the cash payment option after winning, whereas no winners switched from the cash to the annuity option after winning. These findings suggest that real-world choices involving large sums of money may be subject to diminishing marginal utility and probability and delay discounting.

Research paper thumbnail of Delay Discounting in Current and Former Marijuana-Dependent Individuals

Experimental and Clinical Psychopharmacology, 2010

Studies have found that a variety of drug dependent groups discount delayed rewards more than mat... more Studies have found that a variety of drug dependent groups discount delayed rewards more than matched-controls. This study compared delay discounting for a hypothetical $1000 reward among dependent marijuana users, former dependent marijuana users, and matched-controls. Discounting of marijuana was also assessed in the currently marijuana-dependent group. No significant difference in discounting was detected among the groups, however currently dependent users showed a trend to discount money more than the other two groups. Within the dependent marijuana group, marijuana was discounted more than money, and discounting for money and marijuana were significantly and positively correlated. Regression analyses indicated that delay discounting was more closely associated with tobacco use than marijuana use. A variety of questionnaires were also administered, including impulsivity questionnaires. Dependent marijuana users scored as significantly more impulsive on the Impulsiveness subscale of the Eysenck Impulsiveness-Venturesomeness-Empathy questionnaire than controls. However, the three groups did not significantly differ on several other personality questionnaires including the Barratt Impulsivity Scale-11. The Stanford Time Perception Inventory Present-Fatalistic subscale was positively correlated with money and marijuana discounting, indicating that a greater sense of powerlessness over the future is related to greater delay discounting. Results suggest that current marijuana dependence may be associated with a trend

Research paper thumbnail of Moderate Drug Use and Delay Discounting: A Comparison of Heavy, Light, and Never Smokers

Experimental and Clinical Psychopharmacology, 2007

Delay discounting was examined in light smokers (10 or fewer cigarettes per day) and compared wit... more Delay discounting was examined in light smokers (10 or fewer cigarettes per day) and compared with previously published delay discounting data for heavy and never smokers. Participants evaluated several hypothetical outcomes: money gains and loses ($10, 100,and100, and 100,and1,000), health gains and losses (durations of improved and impoverished health subjectively equivalent to 1,000),cigarettegainsandlosses(amountssubjectivelyequivalentto1,000), cigarette gains and losses (amounts subjectively equivalent to 1,000),cigarettegainsandlosses(amountssubjectivelyequivalentto1,000), and potentially real rewards ($10 and $100). Light smokers discounted money significantly more than never smokers, but light smokers did not differ from heavy smokers. The 3 groups did not statistically differ in discounting of health consequences. Similarly, the 2 smoking groups were not found to differ in discounting of cigarettes. Like heavy smokers, light smokers discounted cigarettes significantly more than money and health. Several significant, positive correlations were found between smoking rate and various discounting measures in the heavy smokers but not in the light smokers. Several previous findings were replicated, helping to validate the present results: the sign effect (greater discounting of gains than losses), the magnitude effect (greater discounting of smaller rewards), reliability of discounting measures over time, and the consistency of hypothetical and potentially real rewards. These data suggest that even moderate levels of drug use may be associated with high delay discounting levels.

Research paper thumbnail of Delay Discounting in Current and Never-Before Cigarette Smokers: Similarities and Differences Across Commodity, Sign, and Magnitude

Journal of Abnormal Psychology, 2003

Research has found that nicotine-dependent individuals delay discount monetary gains at a higher ... more Research has found that nicotine-dependent individuals delay discount monetary gains at a higher rate than matched controls. Delay discount rates, however, have also been found to vary across within-subject variables such as the magnitude of the outcome (e.g., 10or10 or 10or1,000), whether the outcome constitutes a gain or a loss, and the commodity being evaluated (e.g., money or health). The present study comprehensively investigated the differences in delay discounting between current and never-before cigarette smokers and across these within-subject variables. Both groups exhibited a magnitude, sign, and commodity effect. Current smokers' delay discount rates for monetary outcomes, however, were higher than never-before smokers across all magnitudes and both signs. This trend was also found for delayed health outcomes, but failed to reach significance.

Research paper thumbnail of Optimism, Financial Literacy and Participation

Research paper thumbnail of Optimism, Financial Literacy and Participation

SSRN Electronic Journal, 2000

Research paper thumbnail of Delay discounting differs between current and never-smokers across commodities, sign, and magnitudes

Research paper thumbnail of Learning by pigeons playing against tit-for-tat in an operant prisoner's dilemma.

Each of four pigeons was exposed to a single random-ratio schedule of reinforcement in which the ... more Each of four pigeons was exposed to a single random-ratio schedule of reinforcement in which the probability of reinforcement for a peck on either of two keys was 1/25. Reinforcer amounts were determined by an iterated prisoner's dilemma (IPD) matrix in which the "other player" (a computer) played tit-for-tat. One key served as the cooperation (C) key; the other served as the defection (D) key. If a peck was scheduled to be reinforced and the D-key was pecked, the immediate reinforcer of that peck was always higher than it would have been had the C-key been pecked. However, if the C-key was pecked and the following peck was scheduled to be reinforced, reinforcement amount for pecks on either key were higher than they would have been if the previous peck had been on the D-key. Although immediate reinforcement was always higher for D-pecks, the overall reinforcement rate increased linearly with the proportion of C-pecks. C-pecks thus constituted a form of self-control. All the pigeons initially defected with this procedure. However, when feedback signals were introduced that indicated which key had last been pecked, cooperation (relative rate of C-pecks)--hence, self-control--increased for all the pigeons.

Research paper thumbnail of Probability of reciprocation in repeated prisoner's dilemma games

Journal of Behavioral Decision Making, 2001

Both social cooperation and self!control require reciprocation[ In social coop! eration situation... more Both social cooperation and self!control require reciprocation[ In social coop! eration situations a single person|s cooperative act\ if not reciprocated by others\ would be unreinforced both immediately and in the long term[ Similarly\ a single act of self!control "refusing a single cigarette\ for example#\ if not followed up by other such acts\ would also be unreinforced immediately and in the long term[ The present experiments varied probability of reciprocation in a prisoner|s dilemma! like game that could resemble a social cooperation or a self!control situation[ Participants earned points by playing against a computer[ The computer o}ered the participant a choice between 4 or 5 points "{cooperation| by the computer# or between 0 or 1 points "{defection| by the computer#[ The participant|s choice of the lesser alternative "{cooperation|# or the greater alternative "{defection|# on the current trial led\ respectively\ to cooperation or defection by the computer on the next trial with a probability "probability of reciprocation\ PR# which could vary[ When PR was greater than 52)\ consistent cooperation maximized the par! ticipant|s earnings[ When PR was less than 52)\ defection maximized earnings[ Three conditions were studied] PR signaled by spinners^PR unsignaled^PR unsig! naled with participants believing that they were playing with another person\ not the computer[ With PR 099) "{tit!for!tat|# and PR 49)\ the modal participant maximized earnings under all three conditions[ With PR 64)\ par! ticipants maximized earnings only when PR was signaled[ These results indicate that di}erences between people|s tendency to cooperate with other people "social cooperation# and their tendency to cooperate with their own future interests "self! control# may lie in di}erences in subjective PR[ public radio station and deposit their litter in the trash can\ for examples\ only if they believe that others will do the same[ If other people fail to cooperate "if they defect#\ a single individual|s cooperative act loses its function "the public radio station goes o} the air\ the streets are dirty# and is wasted[ Reciprocation is similarly important in self!control situations[ The immediate bene_ts of drinking\ overeating\ and smoking\ for example\ are often greater than those of their alternatives * refusing the drink\ the rich dessert\ the cigarette[ To attain the lon`!term bene_ts of sobriety\ diet\ and health one has to put together a long series of such refusals[ A heavy smoker who\ with great e}ort\ gives up smoking today\ and then resumes smoking tomorrow\ will have wasted the e}ort of not smoking today[ An act of self!control is thus\ in a sense\ an act of cooperation with one|s long!term interestsâ n impulsive act is a defection from those interests "Ainslie\ 0881#[ For self!control to succeed it is important that today|s act of self!control be reciprocated by tomorrow|s[ In other words\ while social cooperation requires reciprocation between individuals over social space\ self!control requires reciprocation by an individual over time[ All three of the present experiments varied the probability of reciprocation of cooperation and defection by individual subjects playing a prisoner|s dilemma!like game with a computer[ The _rst two experiments resembled self!control situations in the sense that choice of a larger reward on the current trial could lead to lower overall reward[ The third experiment resembled a social!cooperation situationŝ ubjects believed they were playing the prisoner|s dilemma game against another subject[ The prisoner|s dilemma game "Axelrod\ 0873^Rapoport and Chammah\ 0854# epitomizes a common social dilemma * a con~ict between the interests of an individual and those of a group containing the individual[ Exhibit 0"a# is a contingency matrix of a typical two!player prisoner|s dilemma game[ The numbers in the matrix represent amounts of reward "in points convertible to dollars\ for example# for two players "A and B# contingent on each player|s choice between two alternatives] cooperate "C# or Exhibit 0[ "a# Contingency matrix of a typical two!player prisoner|s dilemma game[ The numbers in the matrix represent amounts of reward for two players "A and B# contingent on each player|s choice between two alternatives] cooperate "C# or defect "D#[ If both players cooperate\ each gets 4 points^if both defect\ each gets 1 points[ If one player cooperates while the other defects\ the cooperator gets 0 point while the defector gets 5 points[ "b# Repeated prisoner|s dilemma game from the viewpoint of Player A[ Player B|s choice "C or D# is represented by the two vertical lines[ If Player B cooperates "left vertical line# Player A earns 5 points by defecting and 4 by cooperatingî f Player B defects "right vertical line# Player A earns 1 points by defecting and 0 by cooperating[ The dashed line shows Player A|s average return\ when playing against tit!for!tat in repeated games\ as a function of Player A|s percent defections "the left vertical line representing no defections and all cooperations\ the right vertical line\ the reverse# PR 099)\ p 9[954[ Exhibit 3 shows the distributions of cooperation choices by participants during the last 19 trials for the three PR conditions^the distributions are heavily skewed with modes towards the extremes "9\ 19\ 19# for the 49)\ 64)\ 099) conditions[

Research paper thumbnail of Teaching and learning in a probabilistic prisoner's dilemma

Behavioural Processes, 2002

The prisoner's dilemma is much studied in social psychology and decision-making because it models... more The prisoner's dilemma is much studied in social psychology and decision-making because it models many real-world conflicts. In everyday terms, the choice to 'cooperate' (maximize reward for the group) or 'defect' (maximize reward for the individual) is often attributed to altruistic or selfish motives. Alternatively, behavior during a dilemma may be understood as a function of reinforcement and punishment. Human participants played a prisoner's-dilemma-type game (for points exchangeable for money) with a computer that employed either a teaching strategy (a probabilistic version of tit-for-tat), in which the computer reinforced or punished participants' cooperation or defection, or a learning strategy (a probabilistic version of Pavlov), in which the computer's responses were reinforced and punished by participants' cooperation and defection. Participants learned to cooperate against both computer strategies. However, in a second experiment which varied the context of the game, they learned to cooperate only against one or other strategy; participants did not learn to cooperate against tit-for-tat when they believed that they were playing against another person; participants did not learn to cooperate against Pavlov when the computer's cooperation probability was signaled by a spinner. The results are consistent with the notion that people are biased not only to cooperate or defect on individual social choices, but also to employ one or other strategy of interaction in a pattern across social choices.

Research paper thumbnail of Probability of reciprocation in repeated prisoner's dilemma games

Journal of Behavioral Decision Making, 2001

Both social cooperation and self!control require reciprocation[ In social coop! eration situation... more Both social cooperation and self!control require reciprocation[ In social coop! eration situations a single person|s cooperative act\ if not reciprocated by others\ would be unreinforced both immediately and in the long term[ Similarly\ a single act of self!control "refusing a single cigarette\ for example#\ if not followed up by other such acts\ would also be unreinforced immediately and in the long term[ The present experiments varied probability of reciprocation in a prisoner|s dilemma! like game that could resemble a social cooperation or a self!control situation[ Participants earned points by playing against a computer[ The computer o}ered the participant a choice between 4 or 5 points "{cooperation| by the computer# or between 0 or 1 points "{defection| by the computer#[ The participant|s choice of the lesser alternative "{cooperation|# or the greater alternative "{defection|# on the current trial led\ respectively\ to cooperation or defection by the computer on the next trial with a probability "probability of reciprocation\ PR# which could vary[ When PR was greater than 52)\ consistent cooperation maximized the par! ticipant|s earnings[ When PR was less than 52)\ defection maximized earnings[ Three conditions were studied] PR signaled by spinners^PR unsignaled^PR unsig! naled with participants believing that they were playing with another person\ not the computer[ With PR 099) "{tit!for!tat|# and PR 49)\ the modal participant maximized earnings under all three conditions[ With PR 64)\ par! ticipants maximized earnings only when PR was signaled[ These results indicate that di}erences between people|s tendency to cooperate with other people "social cooperation# and their tendency to cooperate with their own future interests "self! control# may lie in di}erences in subjective PR[ public radio station and deposit their litter in the trash can\ for examples\ only if they believe that others will do the same[ If other people fail to cooperate "if they defect#\ a single individual|s cooperative act loses its function "the public radio station goes o} the air\ the streets are dirty# and is wasted[ Reciprocation is similarly important in self!control situations[ The immediate bene_ts of drinking\ overeating\ and smoking\ for example\ are often greater than those of their alternatives * refusing the drink\ the rich dessert\ the cigarette[ To attain the lon`!term bene_ts of sobriety\ diet\ and health one has to put together a long series of such refusals[ A heavy smoker who\ with great e}ort\ gives up smoking today\ and then resumes smoking tomorrow\ will have wasted the e}ort of not smoking today[ An act of self!control is thus\ in a sense\ an act of cooperation with one|s long!term interestsâ n impulsive act is a defection from those interests "Ainslie\ 0881#[ For self!control to succeed it is important that today|s act of self!control be reciprocated by tomorrow|s[ In other words\ while social cooperation requires reciprocation between individuals over social space\ self!control requires reciprocation by an individual over time[ All three of the present experiments varied the probability of reciprocation of cooperation and defection by individual subjects playing a prisoner|s dilemma!like game with a computer[ The _rst two experiments resembled self!control situations in the sense that choice of a larger reward on the current trial could lead to lower overall reward[ The third experiment resembled a social!cooperation situationŝ ubjects believed they were playing the prisoner|s dilemma game against another subject[ The prisoner|s dilemma game "Axelrod\ 0873^Rapoport and Chammah\ 0854# epitomizes a common social dilemma * a con~ict between the interests of an individual and those of a group containing the individual[ Exhibit 0"a# is a contingency matrix of a typical two!player prisoner|s dilemma game[ The numbers in the matrix represent amounts of reward "in points convertible to dollars\ for example# for two players "A and B# contingent on each player|s choice between two alternatives] cooperate "C# or Exhibit 0[ "a# Contingency matrix of a typical two!player prisoner|s dilemma game[ The numbers in the matrix represent amounts of reward for two players "A and B# contingent on each player|s choice between two alternatives] cooperate "C# or defect "D#[ If both players cooperate\ each gets 4 points^if both defect\ each gets 1 points[ If one player cooperates while the other defects\ the cooperator gets 0 point while the defector gets 5 points[ "b# Repeated prisoner|s dilemma game from the viewpoint of Player A[ Player B|s choice "C or D# is represented by the two vertical lines[ If Player B cooperates "left vertical line# Player A earns 5 points by defecting and 4 by cooperatingî f Player B defects "right vertical line# Player A earns 1 points by defecting and 0 by cooperating[ The dashed line shows Player A|s average return\ when playing against tit!for!tat in repeated games\ as a function of Player A|s percent defections "the left vertical line representing no defections and all cooperations\ the right vertical line\ the reverse# PR 099)\ p 9[954[ Exhibit 3 shows the distributions of cooperation choices by participants during the last 19 trials for the three PR conditions^the distributions are heavily skewed with modes towards the extremes "9\ 19\ 19# for the 49)\ 64)\ 099) conditions[

Research paper thumbnail of Reinforcement and punishment in the prisoner's dilemma game

Psychology of Learning and Motivation, 2000

... Reinforcement and punishment in the prisoner's dilemma game. ... The prisone... more ... Reinforcement and punishment in the prisoner's dilemma game. ... The prisoner's dilemma is important because it mirrors many dilemmas of everyday life. The name, "prisoner'sdilemma," comes from the common occurrence wherein ...

Research paper thumbnail of Learning by pigeons playing against tit-for-tat in an operant prisoner’s dilemma

Learning & Behavior, 2003

Each of four pigeons was exposed to a single random-ratio schedule of reinforcement in which the ... more Each of four pigeons was exposed to a single random-ratio schedule of reinforcement in which the probability of reinforcement for a peck on either of two keys was 1/25. Reinforcer amounts were determined by an iterated prisoner’s dilemma (IPD) matrix in which the “other player” (a computer) playedtit-for-tat. One key served as thecooperation(C) key; the other served as thedefection(D) key. If a peck was scheduled to be reinforced and the D-key was pecked, the immediate reinforcer of that peck was always higher than it would have been had the C-key been pecked. However, if the C-key was pecked and thefollowing peck was scheduled to be reinforced, reinforcement amount for pecks on either key were higher than they would have been if the previous peck had been on the D-key. Although immediate reinforcement was always higher for D-pecks, the overall reinforcement rate increased linearly with the proportion of C-pecks. C-pecks thus constituted a form of self-control. All the pigeons initially defected with this procedure. However, when feedback signals were introduced that indicated which key had last been pecked,cooperation (relative rate of C-pecks)—hence, self-control—increased for all the pigeons.

Research paper thumbnail of Self-control by pigeons in the prisoner's dilemma

Psychonomic Bulletin & Review, 2002

Pigeons played a repeated prisoner's dilemma game against a computer that reflected their choices... more Pigeons played a repeated prisoner's dilemma game against a computer that reflected their choices: If a pigeon cooperated on trial n, the computer cooperated on trial n + 1; if the pigeon defected on trial n, the computer defected on trial n + 1. Cooperation thus maximized reinforcement in the long term, but defection was worth more on the current trial. Under these circumstances, pigeons normally defect. However, when a signal correlated with the pigeon's previous choice immediately followed each current trial choice, some pigeons learned to cooperate. Furthermore, cooperation was higher when trials were close together in time than when they were separated by long intertrial intervals.

Research paper thumbnail of Delay Discounting in Current and Never-Before Cigarette Smokers: Similarities and Differences Across Commodity, Sign, and Magnitude

Journal of Abnormal Psychology, 2003

Research has found that nicotine-dependent individuals delay discount monetary gains at a higher ... more Research has found that nicotine-dependent individuals delay discount monetary gains at a higher rate than matched controls. Delay discount rates, however, have also been found to vary across within-subject variables such as the magnitude of the outcome (e.g., 10or10 or 10or1,000), whether the outcome constitutes a gain or a loss, and the commodity being evaluated (e.g., money or health). The present study comprehensively investigated the differences in delay discounting between current and never-before cigarette smokers and across these within-subject variables. Both groups exhibited a magnitude, sign, and commodity effect. Current smokers' delay discount rates for monetary outcomes, however, were higher than never-before smokers across all magnitudes and both signs. This trend was also found for delayed health outcomes, but failed to reach significance.

Research paper thumbnail of Decision-making in state lotteries: Half now or all of it later

Psychonomic Bulletin & Review, 2003

Many state lotteries offer players a choice between receiving roughly half of the jackpot immedia... more Many state lotteries offer players a choice between receiving roughly half of the jackpot immediately and receiving the entire jackpot over 25 annual payments. This requires players to make a decision that involves uncertainty, delay, and large amounts of real money. Archival data on lottery players’ jackpot payment decisions were collected from seven state and three multistate lotteries. Players’ jackpot payment preferences were assessed at the time of ticket purchase and after winning a jackpot. Preference for the annuity payment option significantly decreased as jackpot size increased, both at the time of ticket purchase and after winning. Furthermore, a significant proportion of winners who selected the annuity payment option at ticket purchase switched to the cash payment option after winning, whereas no winners switched from the cash to the annuity option after winning. These findings suggest that real-world choices involving large sums of money may be subject to diminishing marginal utility and probability and delay discounting.

Research paper thumbnail of Delay Discounting in Current and Former Marijuana-Dependent Individuals

Experimental and Clinical Psychopharmacology, 2010

Studies have found that a variety of drug dependent groups discount delayed rewards more than mat... more Studies have found that a variety of drug dependent groups discount delayed rewards more than matched-controls. This study compared delay discounting for a hypothetical $1000 reward among dependent marijuana users, former dependent marijuana users, and matched-controls. Discounting of marijuana was also assessed in the currently marijuana-dependent group. No significant difference in discounting was detected among the groups, however currently dependent users showed a trend to discount money more than the other two groups. Within the dependent marijuana group, marijuana was discounted more than money, and discounting for money and marijuana were significantly and positively correlated. Regression analyses indicated that delay discounting was more closely associated with tobacco use than marijuana use. A variety of questionnaires were also administered, including impulsivity questionnaires. Dependent marijuana users scored as significantly more impulsive on the Impulsiveness subscale of the Eysenck Impulsiveness-Venturesomeness-Empathy questionnaire than controls. However, the three groups did not significantly differ on several other personality questionnaires including the Barratt Impulsivity Scale-11. The Stanford Time Perception Inventory Present-Fatalistic subscale was positively correlated with money and marijuana discounting, indicating that a greater sense of powerlessness over the future is related to greater delay discounting. Results suggest that current marijuana dependence may be associated with a trend

Research paper thumbnail of Moderate Drug Use and Delay Discounting: A Comparison of Heavy, Light, and Never Smokers

Experimental and Clinical Psychopharmacology, 2007

Delay discounting was examined in light smokers (10 or fewer cigarettes per day) and compared wit... more Delay discounting was examined in light smokers (10 or fewer cigarettes per day) and compared with previously published delay discounting data for heavy and never smokers. Participants evaluated several hypothetical outcomes: money gains and loses ($10, 100,and100, and 100,and1,000), health gains and losses (durations of improved and impoverished health subjectively equivalent to 1,000),cigarettegainsandlosses(amountssubjectivelyequivalentto1,000), cigarette gains and losses (amounts subjectively equivalent to 1,000),cigarettegainsandlosses(amountssubjectivelyequivalentto1,000), and potentially real rewards ($10 and $100). Light smokers discounted money significantly more than never smokers, but light smokers did not differ from heavy smokers. The 3 groups did not statistically differ in discounting of health consequences. Similarly, the 2 smoking groups were not found to differ in discounting of cigarettes. Like heavy smokers, light smokers discounted cigarettes significantly more than money and health. Several significant, positive correlations were found between smoking rate and various discounting measures in the heavy smokers but not in the light smokers. Several previous findings were replicated, helping to validate the present results: the sign effect (greater discounting of gains than losses), the magnitude effect (greater discounting of smaller rewards), reliability of discounting measures over time, and the consistency of hypothetical and potentially real rewards. These data suggest that even moderate levels of drug use may be associated with high delay discounting levels.