Substitution effects in a generalized token economy with pigeons

Pigeons made repeated choices between earning and exchanging reinforcer‐specific tokens (green tokens exchangeable for food, red tokens exchangeable for water) and reinforcer‐general tokens (white tokens exchangeable for food or water) in a closed token economy. Food and green food tokens could be earned on one panel; water and red water tokens could be earned on a second panel; white generalized tokens could be earned on either panel. Responses on one key produced tokens according to a fixed‐ratio schedule, whereas responses on a second key produced exchange periods, during which all previously earned tokens could be exchanged for the appropriate commodity. Most conditions were conducted in a closed economy, and pigeons distributed their token allocation in ways that permitted food and water consumption. When the price of all tokens was equal and low, most pigeons preferred the generalized tokens. When token‐production prices were manipulated, pigeons reduced production of the tokens that increased in price while increasing production of the generalized tokens that remained at a fixed price. The latter is consistent with a substitution effect: Generalized tokens increased and were exchanged for the more expensive reinforcer. When food and water were made freely available outside the session, token production and exchange was sharply reduced but was not eliminated, even in conditions when it no longer produced tokens. The results join with other recent data in showing sustained generalized functions of token reinforcers, and demonstrate the utility of token‐economic methods for assessing demand for and substitution among multiple commodities in a laboratory context.     

RISKY CHOICE IN PIGEONS: PREFERENCE FOR AMOUNT VARIABILITY USING A TOKEN-REINFORCEMENT SYSTEM

Pigeons were given repeated choices between variable and fixed numbers of token reinforcers (stimulus lamps arrayed above the response keys), with each earned token exchangeable for food. The number of tokens provided by the fixed‐amount option remained constant within blocks of sessions, but varied parametrically across phases, assuming values of 2, 4, 6, or 8 tokens per choice. The number of tokens provided by the variable‐amount option varied between 0 and 12 tokens per choice, arranged according to an exponential or rectangular distribution. In general, the pigeons strongly preferred the variable option when the fixed option provided equal or greater numbers of tokens than the variable amount. Preference for the variable amount decreased only when the alternatives provided widely disparate amounts favoring the fixed amount. When tokens were removed from the experimental context, preference for the variable option was reduced or eliminated, suggesting that the token presentation played a key role in maintaining risk‐prone choice patterns. Choice latencies varied inversely with preferences, suggesting that local analyses may provide useful ancillary measures of reinforcer value. Overall, the results indicate that systematic risk sensitivity can be attained with respect to reinforcer amount, and that tokens may be critical in the development of such preferences.     

Preferences for token exchange‐production schedules: Effects of task difficulty and token‐production schedules

Previous research suggests that accumulated exchange‐production schedules promote increased work completion and are more preferred than distributed exchange‐production schedules. The purpose of this study was to evaluate whether the response effort or token‐production schedules associated with token delivery influenced preferences for exchange‐production schedules. Tokens exchanged under accumulated schedules were more preferred, relative to distributed schedules, when tokens were earned for completing easy tasks. When participants earned tokens for completing difficult tasks, two of three participants preferred accumulated exchange‐production schedules (Experiment 1). Under dense token‐production schedules, accumulated exchange‐production schedules were preferred, but participant's preferences switched to distributed schedules under increasing token‐production (i.e., leaner) schedules (Experiment 2).     

Token reinforcement, choice, and self-control in pigeons.

Pigeons were exposed to self-control procedures that involved illumination of light-emitting diodes (LEDs) as a form of token reinforcement. In a discrete-trials arrangement, subjects chose between one and three LEDs; each LED was exchangeable for 2-s access to food during distinct posttrial exchange periods. In Experiment 1, subjects generally preferred the immediate presentation of a single LED over the delayed presentation of three LEDs, but differences in the delay to the exchange period between the two options prevented a clear assessment of the relative influence of LED delay and exchange-period delay as determinants of choice. In Experiment 2, in which delays to the exchange period from either alternative were equal in most conditions, all subjects preferred the delayed three LEDs more often than in Experiment-1. In Experiment 3, subjects preferred the option that resulted in a greater amount of food more often if the choices also produced LEDs than if they did not. In Experiment 4, preference for the delayed three LEDs was obtained when delays to the exchange period were equal, but reversed in favor of an immediate single LED when the latter choice also resulted in quicker access to exchange periods. The overall pattern of results suggests that (a) delay to the exchange period is a more critical determinant of choice than is delay to token presentation; (b) tokens may function as conditioned reinforcers, although their discriminative properties may be responsible for the self-control that occurs under token reinforcer arrangements; and (c) previously reported differences in the self-control choices of humans and pigeons may have resulted at least in part from the procedural conventions of using token reinforcers with human subjects and food reinforcers with pigeon subjects.     

An experimental evaluation of tokens as conditioned reinforcers in retarded children

Since the publication of experimental reports by Wolfe (1936) and Cowles (1937), that tokens could be established as conditioned reinforcers, many accounts have appeared on the implementation of token systems in human subjects. Tokens have been successfully used as prosthetic motivational devices in a great variety of situations and subjects, such as retarded children (Birnbrauer, Wolf, Kidder and Tague, 1965), adult psychotics (Ayllon and Azrin, 1969), delinquent children and adolescents (Tyler, 1967; Phillips and Wolf, 1968), low achievers in schools (Clark, Lachowicz and Wolf, 1968), emotionally disturbed children (Hewett, Taylor and Artuso, 1969) and in normal classroom settings (O'Leary, Becker, Evans and Saudargas, 1969). In these reports, administration of tokens usually produced an increase in the frequency of desirable social and productive behavior. However, none of these studies showed that the effect of the tokens depended on their role as conditioned reinforcers based on the standard exchange systems being used. No assessment was provided about the separate contribution of the social reinforcement operations involved in dispensing tokens in a social setting.A suggestion about the possible confounding effects of social reinforcement in token administration comes from the failure to establish token systems in subjects who are partially unresponsive to social reinforcement (Hamblin et al., 1970; Ribes and Souza e Silva, in preparation). The present research was conducted with the aim of isolating the effects of conditioned reinforcement as such—apart from those produced by the social reinforcement provided in the delivery of tokens.     

Token Causal Powers

This paper proposes that the relation between property instances and token causal powers is akin to the relation between primary substances and property instances on the Aristotelian account of property instantiation. This view permits an individual to have two tokens of the same type of causal power. Paul Audi has argued that this cannot be: two tokens of the same power type are discernible, he claims, only if they are borne by discernible individuals (Audi 2012, 666). In the context of this criticism, he proposes that power tokens are individuated in part by the individuals bearing them. This paper responds to Audi’s criticism and argues against his preferred view. This paper thus establishes a theory of token causal powers where previously the literature contained only a presumed view and Audi’s objections.     

Incentivizing physical activity using token reinforcement with preschool children

We combined several single‐subject designs to assess the effects of contingent and noncontingent token reinforcement on moderate‐to‐vigorous physical activity (MVPA) exhibited by 4 preschool‐aged children. Higher overall levels and longer bouts of MVPA reliably occurred when tokens were delivered contingent on MVPA for 3 of the 4 children when compared to baseline (no token) and for 2 of the 4 children when compared to noncontingent‐token conditions. The present study demonstrated that the delivery of tokens contingent on MVPA can increase and maintain MVPA exhibited by preschool‐aged children, resulting in more MVPA than in baseline conditions and conditions in which tokens are awarded without respect to MVPA. These results demonstrate that token economies can be used to increase MVPA and they add to the evidence base supporting the use of token economies to address a range of behavior problems.     

Numerical judgments by chimpanzees (Pan troglodytes) in a token economy

We presented four chimpanzees with a series of tasks that involved comparing two token sets or comparing a token set to a quantity of food. Selected tokens could be exchanged for food items on a one-to-one basis. Chimpanzees successfully selected the larger numerical set for comparisons of 1 to 5 items when both sets were visible and when sets were presented through one-by-one addition of tokens into two opaque containers. Two of four chimpanzees used the number of tokens and food items to guide responding in all conditions, rather than relying on token color, size, total amount, or duration of set presentation. These results demonstrate that judgments of simultaneous and sequential sets of stimuli are made by some chimpanzees on the basis of the numerousness of sets rather than other non-numerical dimensions. The tokens were treated as equivalent to food items on the basis of their numerousness, and the chimpanzees maximized reward by choosing the larger number of items in all situations.     

Determinants of pigeons' choices in token-based self-control procedures

Four pigeons were exposed to a token-based self-control procedure with stimulus lights serving as token reinforcers. Smaller-reinforcer choices produced one token immediately; larger-reinforcer choices produced three tokens following a delay. Each token could be exchanged for 2-s access to food during a signaled exchange period each trial. The main variables of interest were the exchange delays (delays from the choice to the exchange stimulus) and the food delays (also timed from the choice), which were varied separately and together across blocks of sessions. When exchange delays and food delays were shorter following smaller-reinforcer choices, strong preference for the smaller reinforcer was observed. When exchange delays and food delays were equal for both options, strong preference for the larger reinforcer was observed. When food delays were equal for both options but exchange delays were shorter for smaller-reinforcer choices, preference for the larger reinforcer generally was less extreme than under conditions in which both exchange and food delays were equal. When exchange delays were equal for both options but food delays were shorter for smaller-reinforcer choices, preference for the smaller reinforcer generally was less extreme than under conditions in which both exchange and food delays favored smaller-reinforcer choices. On the whole, the results were consistent with prior research on token-based self-control procedures in showing that choices are governed by reinforcer immediacy when exchange and food delays are unequal and by reinforcer amount when exchange and food delays are equal. Further, by decoupling the exchange delays from food delays, the results tentatively support a role for the exchange stimulus as a conditioned reinforcer.     

Paired-associate learning by normal children and retardates with relevant redundant compound stimuli

During daily sessions four first-grade boys each played a two-choice marble dropping game. When one colored light was presented a plain token was dispensed as soon as S dropped a marble, and when another light was on a token with a hole in its center was delivered. During choice trials that were interspersed among single-color trials S had to choose one of the two different colored holes. At the end of each session S traded tokens with holes for pennies and then turned in the remaining plain tokens which were not exchanged for money. After S had developed a preference for the response that earned the tokens with holes (tokens that were backed up with pennies) E instructed S to try to get as many plain tokens (unexchangeable tokens) as he could. All Ss immediately switched to the response that earned unexchangeable tokens but as soon as E left they returned to choosing the backed up response. When the adult reentered, Ss again chose to work for unexchangeable tokens. Two different Es (male and female) served and the instructions of each were effective in controlling responding as long as the adult was present, except for one S who did not respond to one E, but did respond as described for the other.     

The effects of token procedures on a teacher's social contacts with her students

The effects of a token system on a teacher's rate of social contacts with her students were investigated in a public school kindergarten. A group of six children were observed daily during a 20-min handwriting lesson. The children were divided into two groups (A and B) of three children each. Five conditions were imposed sequentially: (1) baseline without tokens, (2) contingent tokens for Group A, noncontingent tokens for Group B, (3) contingent tokens for Group B, noncontingent tokens for Group A, (4) reinstatement of condition 2, and (5) contingent tokens for both groups. It was consistently observed that the teacher's rate of social contact was higher with the children receiving the contingent tokens than with those who received noncontingent tokens.     

ALPHABET LETTERS AS TOKENS: TRAINING PRESCHOOL CHILDREN IN LETTER RECOGNITION AND LABELLING DURING A TOKEN EXCHANGE PERIOD1

In token economies, we typically consider the instructional opportunities available during the periods of token delivery, but may overlook educational opportunities available at the time of token exchange. The present studies examined the use of labelled tokens and routines in the token exchange period to teach alphabet letter recognition to economically disadvantaged preschool children. The children earned points for a variety of academic behaviors in an early morning classroom setting. At no time were alphabet letters introduced or taught during class. Later, during a midmorning token exchange period, operated according to a department store model, the children were given their points in the form of poker chips inscribed with upper-case alphabet letters. They were required to discriminate among these lettered chips before exchanging them for backup reinforcers sold in four or five stores. To assess alphabet letter knowledge, probe evaluations were periodically conducted in which questions requiring alphabet letter recognition and labelling were asked. The answers to these questions were not reinforced. Alphabet letter training during token exchange periods consisted of having a child display the lettered chips, whereupon a teacher asked a number of recognition-type questions. Wrong answers were corrected, and correct answers praised. The child was allowed to exchange the tokens when the number required for a purchase had been recognized correctly. The periodic probe evaluations revealed consistent increases in correct alphabet letter recognition and, as a byproduct, alphabet labelling was facilitated, even though not explicitly trained. Thus, once the letters were recognized, correct labelling shortly followed. The sequential training of new sets of letters was used to demonstrate experimental control within subjects for two children. A control for exposure to the letters was provided by using the labelled tokens, but requiring the counting of chips rather than letter discrimination in the exchange period for two other children. This procedure produced chance levels of letter recognition, which were subsequently improved when the discrimination procedure was added. Posttraining probes, conducted at one and three weeks after training when the labelled tokens and discrimination routines were no longer in use, revealed the same high levels of recognition and labelling performance found during training. Thus, it appears that labelled tokens may be used to teach discriminations during token exchange periods so long as responses are differentiated on the basis of relevant dimensions of the stimuli.     

Assessing the value of choice in a token system

Responding of 4 children was assessed under conditions in which (a) no programmed contingencies were arranged for target behavior, (b) responding produced tokens that could be exchanged for a single highly preferred edible item, and (c) responding produced a token that could be exchanged for a variety of preferred edible items. After assessing the effects of these contingencies, the preferences of 3 participants were assessed using a concurrent-chains schedule. Preference for the opportunity to choose from the same or qualitatively different edible items varied across participants, and findings were generally consistent with those of Tiger, Hanley, and Hernandez (2006).     

Stock optimizing in choice when a token deposit is the operant.

Each of 2 monkeys typically earned their daily food ration by depositing tokens in one of two slots. Tokens deposited in one slot dropped into a bin where they were kept (token kept). Deposits to a second slot dropped into a bin where they could be obtained again (token returned). In Experiment 1, a fixed-ratio (FR) 5 schedule that provided two food pellets was associated with each slot. Both monkeys preferred the token-returned slot. In Experiment 2, both subjects chose between unequal FR schedules with the token-returned slot always associated with the leaner schedule. When the FRs were 2 versus 3 and 2 versus 6, preferences were maintained for the token-returned slot; however, when the ratios were 2 versus 12, preference shifted to the token-kept slot. In Experiment 3, both monkeys chose between equal-valued concurrent variable-interval variable-interval schedules. Both monkeys preferred the slot that returned tokens. In Experiment 4, both monkeys chose between FRs that typically differed in size by a factor of 10. Both monkeys preferred the FR schedule that provided more food per trial. These data show that monkeys will choose so as to increase the number of reinforcers earned (stock optimizing) even when this preference reduces the rate of reinforcement (all reinforcers divided by session time).     

Socially learned preferences for differentially rewarded tokens in the brown capuchin monkey (Cebus apella)

Social learning is assumed to underlie traditions, yet evidence indicating social learning in capuchin monkeys (Cebus apella), which exhibit traditions, is sparse. The authors tested capuchins for their ability to learn the value of novel tokens using a previously familiar token-exchange economy. Capuchins change their preferences in favor of a token worth a high-value food reward after watching a conspecific model exchange 2 differentially rewarded tokens, yet they fail to develop a similar preference after watching tokens paired with foods in the absence of a conspecific model. They also fail to learn that the value of familiar tokens has changed. Information about token value is available in all situations, but capuchins seem to pay more attention in a social situation involving novel tokens.     

Relative efficacy of two token economy procedures for decreasing the disruptive classroom behavior of retarded children

Numerous studies have demonstrated that disruptive classroom behavior can be decreased by delivering tokens contingent upon periods of time during which children do not engage in it or by removing tokens contingent upon its occurrence. To date, the best controlled of these studies have consistently reported the two procedures to be equally effective. However, in these studies, token contingencies have been combined with instructions regarding the contingencies. The present study compared these two procedures when no instructions were given regarding the token contingencies. Token delivery was not effective in decreasing disruptive behavior in any of the children, while a combination of token delivery and removal was effective for three of four children. The results suggest that the combined procedure may be effective with certain populations that are not readily controlled by instructions.     

REINFORCER ACCUMULATION IN A TOKEN-REINFORCEMENT CONTEXT WITH PIGEONS

Four pigeons were exposed to a token-reinforcement procedure with stimulus lights serving as tokens. Responses on one key (the token-production key) produced tokens that could be exchanged for food during an exchange period. Exchange periods could be produced by satisfying a ratio requirement on a second key (the exchange-production key). The exchange-production key was available any time after one token had been produced, permitting up to 12 tokens to accumulate prior to exchange. Token accumulation, measured in terms of both frequency (percent cycles with accumulation) and magnitude (mean number of tokens accumulated), decreased as the token-production ratio increased from 1 to 10 across conditions (with exchange-production ratio held constant), and increased as the exchange-production ratio increased from 1 to 250 across conditions (with token-production ratio held constant). When tokens were removed, accumulation decreased markedly compared to conditions with tokens and the same schedules. These data show that token accumulation is an orderly function of token-production and exchange-production schedules, and they are broadly consistent with a unit-price model based on local and global responses per reinforcer.     

THE EFFECTIVENESS OF REINFORCEMENT,RESPONSE COST,AND MIXED PROGRAMS ON CLASSROOM BEHAVIORS1

Six elementary school children served as subjects in an experiment comparing the relative effectiveness of (1) token reinforcement, in which children received tokens for attending and for correct arithmetic performance; (2) response cost, in which children received “free” tokens at the start of a period but lost them for inattention and for arithmetic performance below a specified level; and (3) a combination of both token reinforcement and response cost. During training, the six subjects received all three procedures in counterbalanced sequence. The effects of the three procedures were assessed by a within-subject comparison divided into three phases: (i) baseline, (ii) training, (iii) withdrawal of tokens. Introduction of the three token procedures markedly increased the two dependent measures. However, there were no differences across the procedures in the amount of change produced in either attending behavior or arithmetic performance. During baseline, the subjects averaged 29% attending behavior and 6.4 correct problems. These levels increased to 85% for attending behavior and 11.4 correct problems for arithmetic performance during training. Removal of all token procedures significantly decreased attending behavior (to an average of 65%), but produced a nonsignificant reduction in arithmetic performance (to an average of 7.6 correct problems). There was evidence that this lack of differential effects of the three token procedures was not due to an inability to discriminate among them. Furthermore, the subjects were evenly divided in their preference for the three procedures.     

Using progressive ratio schedules to evaluate tokens as generalized conditioned reinforcers

The properties of operant reinforcers are dynamic and dependent on a number of variables, such as schedule and effort. There has been sparse research on the generalized conditioned properties of token reinforcement. We evaluated leisure items, edible items, and tokens using a progressive ratio schedule with three children with diagnoses of ASD and developmental delays. The highest break points occurred during the token reinforcement condition for two out of three participants, but response rates tended to be higher with edibles. We then evaluated the effects of presession access to edibles on the break points of edible items and tokens with two participants. Break points decreased only in the edible reinforcement condition, and the participants chose to work for leisure items rather than edibles when presession access to edibles was in place. These findings suggest that the tokens functioned as generalized conditioned reinforcers.     

Memory deficits and memory surfeits: differential cognitive consequences of tokenism for tokens and observers

Historically, women and minority group members have been underrepresented in the professions and in better paying, high-status jobs. Even when they have been admitted to such positions, these underrepresented persons often have been the only member of their social category: a token. Previous field and laboratory research has shown that "tokens" attract disproportionate attention and are either evaluated unfairly or evaluated on the basis of their normal reactions to differential treatment by majority group members. We tested the possibilities of whether tokens might suffer more cognitive deficits than would nontokens, and whether they do so even when they are treated no differently. College students were led to believe that they were sharing their views on everyday topics with three other students (actually videotaped confederates), who were either all of the student's own sex or all of the opposite sex. In a later memory test, token participants remembered fewer of the opinions that they and the three other students had expressed than did nontokens. Observers, in contrast, remembered more of what token subjects said than what the three other students said. Theoretical and public policy implications are discussed.