Association for Behavior Analysis International

The Association for Behavior Analysis International® (ABAI) is a nonprofit membership organization with the mission to contribute to the well-being of society by developing, enhancing, and supporting the growth and vitality of the science of behavior analysis through research, education, and practice.


41st Annual Convention; San Antonio, TX; 2015

Event Details

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Poster Session #85
EAB Saturday PM
Saturday, May 23, 2015
5:00 PM–7:00 PM
Exhibit Hall C (CC)
1. Developing an Animal Model of the Balloon Analogue Risk Task (BART)
Area: EAB; Domain: Basic Research
MARISOL LAUFFER (Reed College), Timothy D. Hackenberg (Reed College), Lavinia C. M. Tan (Reed College)
Abstract: The present study sought to create and test an animal analogue to the Balloon Analogue Risk Task (BART), a commonly used diagnostic procedure for assessing impulsivity. Six pigeons were trained to earn, accumulate, and exchange tokens for food reinforcers, using a touchscreen apparatus. Each peck on a token-production key produced a token, indicated by a small colored symbol on the side of the display. After the first token was earned, the pigeons could choose to earn additional tokens or could exchange earned tokens by completing a fixed ratio requirement on a second (exchange) key. During the exchange period, each earned token flashed on and off, pecks on which produced 3-s of food. After reaching a relatively stable level of token accumulation in the baseline condition, a token-loss contingency was added that operated concurrently with the token-production schedule. Pigeons could continue to earn and accumulate tokens, but also risked losing all tokens accumulated on that trial according to a probabilistic schedule (determined individually for each pigeon based on their baseline accumulation levels). The study represents a first step toward developing a flexible and rigorous animal model of risky choice useful in cross-species analyses.
2. Positive Automaintenance in spontaneously hypertensive (SHR) and normotensive (WKY) Rats
Area: EAB; Domain: Basic Research
CHRISTOPHER MARIO (Salem State University), Carlos F. Aparicio Naranjo Naranjo (Salem State University)
Abstract: The spontaneously hypertensive rat (SHR) has been compared with the normotensive Wistar-Kyoto (WKY) rat when developing rodent models of attention deficit hyperactivity disorder (ADHD). Between-strain differences in response acquisition have been attributed to deficits in attention in the former but not the latter strain. However, conflicting results have been obtained by research that examined differences in the acquisition of lever-pressing between SHR and WKY rats. This raises the possibility that impulsivity, rather than deficits of attention, is the mechanism accounting for differences between strains. The present study used Williams and Williams’ (1969) positive automaintenance procedure to examine lever-pressing acquisition in SHR and WKY rats. In addition, possible strain differences in the maintenance of that behavior were examined using a concurrent-chains procedure. Results of the former procedure showed retarded acquisition of lever-pressing in the WKY rats when compared to the SHRs, suggesting differences in impulsivity between strains. Results of latter procedure showed no differences in the maintenance of lever-pressing between strains, nor were there differences in preference across conditions. These results have implications for the development of rodent models of ADHD using SHR and WKY rats as subjects.
3. Evidence for threat discounting as an individual difference variable in neuroimaging research on anxiety.
Area: EAB; Domain: Basic Research
ADAM BREWER (Florida Institute of Technology ), Sandy Magee (University of North Texas), David M. Richman (Texas Tech University), Simon Dymond (Swansea University), Michael W. Schlund (University of North Texas)
Abstract: Anxiety is characterized by increased attention and hyperactivation in frontal and limbic brain regions to conditioned aversive stimuli or threats. Currently, research on anxiety is increasingly focusing on identifying individual difference variables/factors that modulate brain activation to threats. We propose that the extent to which people discount threats over time is one important variable. To evaluate this idea, we examined the relation between regional brain activation to an unavoidable CS+ threat (designed to provoke fear/anxiety) and threat discounting determined using an adjusting amount delay discounting task with hypothetical monetary losses. Thirty subjects were asked what they would prefer to lose by way of having to pay an amount of money. Subjects were given repeated choices between paying (a) a large $500 delayed loss (under randomized delay conditions of .08, .50, 1, 3, 5, and 10 years) or (b) a smaller $250 immediate loss that titrated across trials. A regression analysis showed individuals with greater threat discounting---those more avoidant of immediate losses---evidenced more reactivity in brain areas associated with threat appraisal (anterior cingulate and medial prefrontal cortex). These findings have considerable translational value by highlighting threat discounting as a potential individual difference variable/factor that may contribute to anxiety pathology.

Discounting of Delayed and Probabilistic Rewards in Mono- and Poly-drug Users

Area: EAB; Domain: Applied Research
DIANA MEJÍA CRUZ (Universidad Nacional Autónoma de México), Leonard Green (Washington University), Joel Myerson (Washington University), Silvia Morales Chaine (UNAM), Javier Nieto Gutierrez (National Automonous University of Mexico)

Performance on a delay discounting task has been related to impatience, whereas performance on a probability discounting task has been related to risk-taking. Substance abusers (e.g., cigarette smokers, heroin and cocaine addicts) exhibit higher rates of delay discounting than controls. Nevertheless, the relation between delay and probability discounting and mono- and poly-drug use has received little attention. The aim of this study was to compare delay and probability discounting by cocaine-dependent participants who score high on second-drug use with those who score low on second-drug use, and by marijuana-dependent participants who score high and low on second-drug use. 144 participants (72 cocaine dependent, 42 marijuana dependent, 30 controls) chose between a smaller, immediate/certain monetary reward and a larger, delayed/probabilistic monetary reward. The amount of the immediate/certain reward was adjusted until it was judged equal in subjective value to the larger reward. Delay discounting was greater in the cocaine group than the marijuana group, but no differences were observed in probability discounting among these groups and that of controls. Correlations between degree of second-drug use and degree of discounting, as measured by area under the curve (AuC), were not statistically significant either within the cocaine-dependent or the marijuana-dependent users.

5. Not so bad: avoidance modulates anterior cingulate and medial prefrontal cortex responses to threat.
Area: EAB; Domain: Basic Research
SANDY MAGEE (University of North Texas), Adam Brewer (Texas Tech University), David M. Richman (Texas Tech University), Simon Dymond (Swansea University), Michael W. Schlund (University of North Texas)
Abstract: The anterior cingulate (ACC) and medial prefrontal cortex (mPFC) play a central role in the discrimination and appraisal of threats—stimuli correlated with punishment. Identification of variables that modulate appraisals and regional activation has important implications for understanding anxiety pathology and treatment development. Avoidance is one variable that is a prominent emotional regulation strategy, but yet its relationship with ACC/mPFC is unknown. In this investigation, thirty healthy adults underwent functional neuroimaging while completing a delayed avoidance task in which conditioned threats (CS+s) were presented 12 s prior to an opportunity to avoid. During the delayed avoidance task, avoidance responding to an Avoidable CS+ threat prevented an aversive stimulus, but not to an Unavoidable CS+ threat. During subsequent extinction, CSs were presented without an opportunity to avoid. The Avoidable CS+ relative to the Unavoidable CS+ was associated with reductions in negative valence, fear and US expectancy and activation. Greater regional activation was consistently observed to the Unavoidable CS+, which was sustained during avoidance and declined during extinction. Results highlight the role of avoidance coping in regulating appraisals and associated anterior cingulate and medial prefrontal cortex responses.
6. Adult ADHD and Decision-Making: Delay Discounting of Money and Condom-Protected Sex
Area: EAB; Domain: Basic Research
MARY MARGARET SWEENEY (Johns Hopkins University School of Medicine), Patrick S. Johnson (Johns Hopkins University School of Medicine), Steven Pennybaker (Johns Hopkins University School of Medicine), Matthew W. Johnson (Johns Hopkins University School of Medicine)
Abstract: Individuals with ADHD have shown a greater preference for smaller sooner over larger later rewards in a delay discounting task relative to those without ADHD. Because research on this topic has been conducted with children and adolescents choosing between monetary rewards, the scope and implications of decision-making research within ADHD are limited. It is unknown whether ADHD symptoms in adults are related to discounting of delayed sexual rewards, namely the choice between immediate, unprotected sex versus delayed sex with a condom. We conducted an online survey using Amazon Mechanical Turk and compared delay discounting of money and condom-protected sex between those who met ADHD screening criteria of the Adult Self-Report Scale and those who did not. Individuals who met ADHD criteria chose smaller sooner rewards more often in the monetary discounting task, and also showed less area under the curve (greater delay discounting) in the Sexual Delay Discounting Task. There was no effect of ADHD medication status or medication type on delay discounting of condom-protected sex or money. These data suggest that the presence of ADHD symptoms in adults may increase the likelihood of engaging in unprotected sex, and consequently to the prevalence of sexually transmitted infections such as HIV.
7. Correlation Between Body Mass Index and Delay Discounting of Different Rewards
Area: EAB; Domain: Basic Research
RAUL AVILA (National Autonomous University of Mexico), Chyntia Diaz (National Autonomous University of Mexico), Aldo Toledo (National Autonomous University of Mexico), Karla Campos (National Autonomous University of Mexico)
Abstract: This study examined the correlations among the discounting of different rewards and the body mass index of 124 adolescents. The subjects were classified according to their body mass index in four groups, namely, low weight, normal weight, overweight and obesity groups. Thereafter they estimated the subjective value of the rewards with Fill in the Blank and Adjusting Amount procedures. The rewards were leisure time, money, fruit, fast food, water and soda tested with the following delays: 1 day, 1 week, 1 month, 6 months, 1 year, 3 years and 5 years. Hyperbolic fittings were found for the six rewards but only with the Adjusting Amount procedure (Figure 1). Significant correlations between AUC for pairs of rewards were found with both procedures and mainly in the normal weight and overweight groups. Therefore, the body mass index emerged as a parameter of the positive discounting trend between rewards. Significant linear regressions showed that there was a relation between increasing body mass index and increasing impulsivity as measured by AUC for most of the rewards tested (Table 1). In conclusion, these findings were interpreted as supporting a continuum between a health related index (i.e., body mass index) and a continuous discounting process.

Children's Performance on the Balloon Analogue Task

Area: EAB; Domain: Basic Research
ARACELI MORENO (Arizona State University), Amanda Small (Arizona State University), Mikayla Gilbreath (Arizona State University), Brandon McColley (Arizona State University), Elias Robles (Arizona State University)

Risk taking has been identified as an important predictor of health status. Among other hazards, individuals who take higher risks are more likely to develop drug and gambling problems. The Balloon Analog Risk Task (BART; Lejuez et al., 2002) and other comparable behavioral analogues have been successfully used to estimate risk taking in adults and adolescents. The purpose of this study was to assess the performance of young children (N=81, 8-10 years old) on a balloon analogue task where pump responses produced points without further value. The results show that, across balloons, girls responded significantly more than boys, that all children show an exponential increase in responding throughout the session, initiate responding faster after losses, and display frequency and recency effects of losses on responding over successive balloons. With exception of the gender differences, the childrens response patterns on the balloon task were similar to those of young adults. While more research is needed, detection of extreme deviations from the general patterns observed may be valuable in identifying children at risk, and may be useful in the evaluation of preventive interventions.

9. The Effects of a Semester Long Financial Education Course on Delay Discounting
Area: EAB; Domain: Basic Research
WILLIAM DEHART (Utah State University), Jean Lown (Utah State University), Amy Odum (Utah State University)
Abstract: Delay-discounting as a behavioral measure of impulsive choice is strongly related to substance abuse and other risky behaviors. Therefore, effective techniques that alter delay discounting are of interest. We explored the ability of a semester long financial education course to change delay discounting. College students were recruited from a financial education course and an abnormal psychology course that was similar in demographics. Both groups completed a delay-discounting task for $100 during the first two (Time 1) and the last two (Time 2) weeks of the semester. Participants chose between a smaller sooner reward and a larger later reward at seven different delays. An indifference point was obtained for each delay. Area under the curve (AUC, a measure of the steepness of discounting) was calculated. AUC between groups was not different at Time 1 but was different at Time 2. The financial education group discounted less at Time 2 than Time 1. AUC for the abnormal psychology group did not change. Students with higher GPA demonstrated the largest change in AUC. Financial education may be an effective method for reducing delay-discounting.
10. Self-Control, Impulsivity, and Delay Discounting In Elementary School Children
Area: EAB; Domain: Basic Research
LORI-ANN B. FORZANO (The College at Brockport, State University of New York), McKenna O'Keefe (The College at Brockport, State University of New York), Michiko Sorama (Kobe Gakuin University)
Abstract: Impulsivity, which can be conceptualized as lack of self-control, is featured in a number of childhood disorders. Many measures have been developed for the construct of impulsivity. The self-control task involves presenting reinforcer alternatives differing in amount and delay and having a child repeatedly choose between larger, more delayed and smaller, less delayed reinforcers. In the delay discounting task, a child is presented with a series of choices between hypothetical rewards available immediately or delayed in time. Although commonly treated as equivalent, the few studies that have directly compared measures, have for the most part observed low degrees of concordance between measures; Hence suggesting that impulsivity is a multidimensional construct. One objective of the current experiment with children (ages 5-12) was to establish the relationship between measures of impulsivity, including the Childrens Delay Discounting Questionnaire (Sorama & Forzano, 2012) and Self-Control in Daily Life Questionnaire (Sorama & Forzano, 2012). Other objectives included, determining the relationship between these measures and age and gender. Preliminary analyses of 63 children, suggest no significant relationships. The results are discussed with respect to their implications for the multidimensional aspect of the construct of impulsivity.
11. Within Subject Comparisons of Indifference Points Obtained From a Survey and a Visual Analogue Scale
Area: EAB; Domain: Basic Research
JONATHAN E. FRIEDEL (Utah State University), Amy Odum (Utah State University)
Abstract: Several methodologies have been proposed to rapidly assess impulsive choice in humans. One limitation of many of these methodologies is that indifference points are not a product of the assessment. An assessment that does not produce indifference points is problematic because they are standard data in delay discounting research. One method for assessing delay discounting that is rapid and produces indifference points is a visual analogue scale. In a visual analogue scale, participants mark the point on a line that represents the present value of some delayed outcome. The visual analogue scale has been shown to produce indifference points that are similar in kind to those produced by other methodologies. However, a direct comparison between a visual analogue scale and a standard technique has not been made. We compare indifference points obtained from a visual analogue scale and indifference points obtained from a version of a standard assessment task (Bickel, Odum, & Madden, 1999). Indifference points obtained from the visual analogue scale are systematically higher than those obtained from a survey method. However, there is a high correlation between indifference points from each measure. The visual analogue scale results in indifference points that are similar to those in another method.
12. Measuring Indifference Points of Ethical Issues Among Future Substance Abuse Counselors.
Area: EAB; Domain: Basic Research
MATTHEW E SPRONG (University of Montana-Billings ), Frank D. Buono (Southern Illinois University)
Abstract: Delay and probability discounting procedures have been utilized to deem many populations as impulsive. However, a vast majority of discounting research is vested in delay discounting, and even less research is investigated in ethical issues. For the current study, we recruited future substance abuse counselors and had them answer three different hypothetical probability discounting scenarios dealing with ethical dilemmas. These scenarios were typical examples seen in everyday life, and the participants were asked to complete the scenarios as if they were real. The results display a similar findings to that of other deemed impulsive populations. Future implications are discusses within the study.

Comparison of Temporal and Probabilistic Discounting Between Smokers, Ex-smokers and Non-smokers Participants

Area: EAB; Domain: Applied Research

More than one billion people around the world smoke tobacco. This consumption kills prematurely nearly 6 million people, causing important economic losses. (WHO, 2011). Specifically, the perspective of probabilistic and temporal discount has been used for the study of impulsivity and risk aversion. In the case of tobacco, several studies show that smokers discounted delayed rewards more than non-smokers (Baker, Johnson y Bickel, 2003; Bickel, Odum y Madden, 1999; Mitchell, 1999). Other studies suggest that abstinence or reduced consumption of tobacco can affect the discount rates of the participants. In a research conducted by Bickel, Odum, and Madden (1999) where ex-smokers, smokers and non-smokers were compared, a smaller discount was found in ex-smokers than in current smokers. The purpose of this study is compare the temporal and probabilistic discount on smokers, ex-smokers and non-smokers. 20 smokers, 20 ex-smokers and 20 non-smokers participated. Fist, they answered the Fagerstrm Test for Nicotine Dependence, then, they answered a computer task, and finally, their level of carbon monoxide was measured by a breath test. A factorial design with three groups was used for each amount of reward discount probabilistic tasks, the participant made six choices for each of five established probabilities. Results showed differences in temporal and probabilistic discount in the three groups. Further studies will help to identify the controlling variables of different types of impulsivity.

14. Effects of deprivation level on probability discounting in pigeons
Area: EAB; Domain: Basic Research
DAIKI MISHIMA (Rikkyo University), Koji Hori (Rikkyo University)
Abstract: We examined effects of deprivation level on probability discounting in four pigeons. There were three conditions of deprivation which included 90, 80 and 70 % of their individual free-feeding weights. An experimental chamber equipped with three keys was used. The center white key was darkened by the first response to it and both side keys were illuminated with white light by the response. A response to one side key resulted in a smaller certain reinforcer, while a response to the other side key resulted in a larger probabilistic reinforcer. The probability decreased across a single session, which included 80, 60, 40 and 20 %. The session consisted of four blocks corresponding to each probability condition and one block included 20 trials. All pigeons generally showed probability discounting, but there were individual differences in effects of deprivation. The present procedure was different from previous studies, thus more replications by same procedure as those studies are needed.
15. The Relation between the Degree of Social Discounting and the Selfishness Measured in Ultimatum Game
Area: EAB; Domain: Basic Research
TAKEHARU IGAKI (Ryutsu Keizai University)
Abstract: The purpose of the present study is to examine the relation between the degree of social discounting and the selfishness measured in Ultimatum game. Jones & Rachlin (2006) indicated that social discounting might be described by a hyperbolic function in which a larger discounting rate would describe more selfish (or less altruistic) choices. On the other hand, the amount of money that proposer offers in Ultimatum game is also viewed as an indication of selfishness. In this study, using Japanese college students as participant, we compared the degree of social discounting with the amount of money the proposer offer in the Ultimatum game through the paper-and-pencil test. The results showed that participants who showed lower value of AUC (area under the curve) proposed higher amount of money kept for themselves than those who show higher value of AUC, suggesting that selfishness measured by social discounting questionnaire and Ultimatum game could be interrelated. However, the results were not so clear. Therefore, more research is needed to specifically examine the meaning of selfishness using another measure. For example, Rachlin & Jones (2008) developed another version of social discounting questionnaire which examines the generosity. It is interesting to examine the relation between the generosity and the selfishness shown by Ultimatum game.
16. Discounting Delayed Rewards as a Function of Delay Until the Smaller Reward
Area: EAB; Domain: Basic Research
BENJAMIN KOWAL (University of Arkansas at Little Rock), Sarah Lassiter (University of Arkansas at Little Rock)
Abstract: Three groups of participants made choices between hypothetical monetary rewards that were either smaller and available after shorter delays (SS rewards) or larger and available after longer delays (LL rewards). Group one was consider a control group and had SS rewards available “today”. Groups two and three were exposed to choices similar to the control group with the exception that a delay was added to both SS and LL rewards (i.e., 7 or 180 days). LL rewards ranged in value from $25 to $85 with delays that ranged from 14 to 366 days. Among groups, the proportion of choices of LL rewards was higher when the delay to both SS and LL rewards was increased by 180 days but not when the delay was increased by only 7 days (F[2,287] = 8.10, p < .001, eta squared = .053). Within participants, the proportion of choices of LL rewards was consistently higher when LL rewards were greater in magnitude (F[2,574] = 103.26, p < .001, eta squared = .265). The present results suggest that the value of monetary outcomes is not always discounted at a constant rate with delay; however, consistency may be found when relatively short front-end delays are examined.
17. Examining Potential Mechanisms of the Effects of Opportunity Costs on Delay Discounting
Area: EAB; Domain: Basic Research
JILLIAN RUNG (Utah State University), Gregory J. Madden (Utah State University)
Abstract: Recent research on delay discounting, or the devaluation of rewards as a function of their delay, has shown that opportunity costs associated with delay can have drastic impacts on an individual’s rate of discounting (Johnson, Hermann, & Johnson, 2014). While there exists much research aimed at elucidating the correlates of an individual’s propensity to discount steeply or shallowly, no work has been conducted to understand the factors that may predict discounting across delays with different costs. In the present study, we assessed discounting in college undergraduates using hypothetical monetary rewards in a standard adjusting amount task, in addition to two tasks in which a choice of the delayed option was framed as a) having no opportunity cost, and b) imposing maximum opportunity cost. The relation between discounting in each of the tasks was assessed with potentially relevant measures, such as distress tolerance and certainty of delayed reward receipt, which could elucidate the processes governing choice across these different types of delays. Preliminary results suggest that certainty of reward receipt is related to choice without opportunity costs, but not with choice under conditions of maximum cost. Alternative mechanisms and the lack of relations between discounting and other measures are discussed.

Delay Discounting of Gains and Losses in marihuana Users with Anxiety and Depression Symptoms

Area: EAB; Domain: Applied Research
SILVIA MORALES CHAINE (National Autonomous University of Mexico), Danae Ramirez Arriaga (National Autonomous University of Mexico)

From the perspective of delay discounting, preference of a small and lower value reward is considered impulsivity. Marijuana users dont have this preference for small and immediate rewards on human and animal models, in contrast to other drugs such as cigarette, cocaine, alcohol and opiates. The objective of this study was to correlate delay discounting of gains and losses (drink, activity, $200, $1500 and $3000) with anxiety and depression scores of the SCL-90 scale. The sample was composed of 31 male marijuana dependents, aged 18 to 50 years old. In the delay discounting task participants chose between a delayed gain: $ 200, $ 3000, 40 units of drink, 100 minutes of free time activity or a delayed loss: $ 1,500 and an immediate option (the magnitude varied by 50% according to election). The delay for each outcome varied in the range of 7, 30, 180, 365, 1095 days. Results showed that high levels of depression correlate significantly with low levels of area under the curve (AUC) that means more impulsiveness in the drink and $200 outcome, no significant results were found in anxiety correlation. Also the AUC scores of most marijuana users were adjusted to quasi-hyperbolic equation.

19. A New Model of Discounting: Choice Between Consequences of Conflicting Valence
Area: EAB; Domain: Basic Research
AARON DUMAS (West Virginia University), Forrest Toegel (West Virginia University), Michael Perone (West Virginia University)
Abstract: Some problematic human behaviors (e.g., binge drinking) can be conceptualized as choice of a large immediate reinforcer followed by a delayed aversive event, in lieu of a small immediate reinforcer and no delayed aversive event. The aim of the present study was to develop an animal laboratory model for studying such choice situations. Rats could choose multiple food pellets plus delayed shock, or a single pellet. Using a titrating procedure, adjustments were made in delay to shock based on choice, and adjustments continued until delay stabilized. Mean delay over the stable period was treated as the indifference point – the delay at which shock devalued multiple pellets to equal the value of a single pellet. Indifference points were generated for different combinations of shock intensity and shock duration. In Experiment 1, stable delay was an increasing function of shock intensity and duration. As shock was made more intense or longer lasting, it needed to be further delayed to obtain indifference. In Experiment 2, adding a signal during the delay did not functionally alter indifference points. This procedure is a viable means of studying choice between a large immediate reinforcer followed by a delayed aversive event, versus a small immediate reinforcer.
20. Discounting of Delayed Lotteries: Simultaneous and Separate Devaluation by Time And Probability
Area: EAB; Domain: Basic Research
WOJCIECH BIALASZEK (University of Social Sciences and Humanities (SWPS)), Piotr Zielonka (Warsaw University of Life Sciences), Pawel Ostaszewski (University of Social Sciences and Humanities)
Abstract: The consequences of our choices are very often delayed and are also probabilistic. The research on delayed lotteries combines two dimensions: time and risk. The present study aims to answer following questions: 1) whether the process of discounting of delayed lotteries is a simple combination of probability and delay discounting processes, 2) is discounting first by probability and than by time (separately) the same as discounting by time in the first stage and than by probability 3) are probability and time independent processes in discounting of delayed lotteries. Participants were 100 university students. The experiment used repeated-measures design. The results show that delayed lotteries are discounted at slower rate when probability and time are combined in one alternative, and that time and probability are separate processes.
21. Descriptive and Arbitrary Verbal Stimuli in an Observing-Response Procedure with Serial Stimuli
Area: EAB; Domain: Basic Research
Katya Quiñones (National Autonomous University of Mexico), ROGELIO ESCOBAR (National Autonomous University of Mexico)
Abstract: This experiment explored the effects of stimuli associated with extinction (S-) signaling the temporal distance to reinforcer delivery on observing responses by college students. Pressing a key resulted in monetary reinforcers on a mixed schedule in which an extinction component of 20, 40, or 60 s was followed by a 20-s random-interval component. Pressing two additional keys produced a 5-s display of verbal stimuli signaling the state of the mixed schedule. For one group of students stimuli consisted of a descriptive message stating the state of the schedule. For example, “At this time no scores can be earned but the state of the program will change soon”. This message differed in each 20-s segment of the extinction component and during the random-interval component. For another group, stimuli consisted on arbitrary labels. For example, “The current status of the program is V” In the two groups, stimuli presented during extinction were removed in a subsequent condition. It was found that observing responses during extinction decreased only when descriptive stimuli were removed. These results suggests that an S- could function as a conditioned reinforcer if it allows describing verbally the temporal distance to reinforcer delivery.
Keyword(s): Poster



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