Within-session Changes In Responding During Concurrent Variable-interval Schedules

Five rats and 4 pigeons responded for food delivered by several concurrent variable-interval schedules. The sum of the rates of reinforcement programmed for the two components varied from 15 to 480 reinforcers per hour in different conditions. Rates of responding usually changed within the experimental session in a similar manner for the two components of each concurrent schedule. The within-session changes were similar to previously reported changes during simple schedules that provided rates of reinforcement equal to the sum of all reinforcers obtained from the concurrent schedules. The number of changeovers also changed within sessions in a manner similar to the changes in instrumental responding. These results suggest that changeovers are governed by the same variables that govern instrumental responding. They also suggest that the within-session change in responding during each component of a concurrent schedule is determined by approximately the sum of the reinforcers obtained from both components when both components provide the same type of reinforcer.     

Effect of upcoming reward type when rats press a lever for ethanol

Rats' operant responding for sucrose rewards in the 1st half of a session can vary directly with the conditions of reward in the 2nd half. The authors investigated whether that induction effect represented an animal model of emotive states. Rats pressed a lever for either ethanol or sucrose rewards in the 1st half of a 40-min session. The reward in the 2nd half of the session was, across conditions, 1% sucrose, a food pellet, or the same reinforcer delivered in the 1st half. When subjects responded for sucrose, upcoming reward type had little influence on responding in the 1st half of the session. However, when subjects responded for ethanol, upcoming 1% sucrose and food-pellet reinforcement both produced increases in responding. The results suggest that the procedure produced different emotive states, but further work is needed to support such a model. The results also have potential applied implications.     

Executive Functioning and Delay Discounting of Four Different Outcomes in University Students

The study investigated a potential relationship between level of executive functioning and rates of delay discounting (i.e., the subjective decrease in the value of an outcome if its delivery is delayed). University students completed an executive-functioning questionnaire and then a delay-discounting task involving four different outcomes (money, cigarettes, dating partner, body image). Results showed that the overall measure of executive functioning was a significant predictor of rates of discounting of three of the four outcomes, and approached significance for the fourth outcome. Further, different subscales of executive functioning were significantly correlated with discounting of different outcomes. These results suggest that executive functioning plays a role in discounting of delayed outcomes and that procedures designed to affect either executive function or delay discounting might result in concomitant changes in the other measure.     

A bird in hand: discouraging gambling on a slot machine simulation

Using a slot machine simulation, our laboratory has found that participants, given the opportunity not to gamble and to keep the money they have been staked, almost always choose to play the simulation. In this study, the authors investigated whether increasing the salience of the money for which participants played or increasing the response effort required to gamble the money would decrease gambling. In Experiment 1, participants in different groups were told about, were shown, or held the dollars 10 they were to be staked to play the simulation. Results showed that participants who held the money prior to gambling played fewer trials and bet less money than participants in other groups. In Experiment 2, participants in different groups were staked with dollars 5 in nickels, quarters, or their choice of nickels or quarters. Results showed that the participants staked with nickels ultimately gambled a similar amount of money as did participants staked with quarters. They did so by playing the simulation more times than the other participants. Participants staked with nickels did, however, end the session with the most money. Findings suggest ways that gambling and gambling losses can be lessened.     

Comparing Delay Discounting Rates When Using the Fill-in-the-Blank and Multiple-Choice Methods

Several methods have been devised to measure delay discounting. The present study recruited university students to complete a delay-discounting task involving five different outcomes (finding a dating partner, free cigarettes, winning $100,000, being owed $100,000, and obtaining one's ideal body image) that was administered using either the fill-in-the blank (FITB) or multiple-choice (MC) method. Results showed that the different administration methods sometimes produced significantly different rates of discounting, the direction of which differed by outcome. Hyperbolic discounting and the area under the discounting curve were nearly always significantly correlated when the FITB method was used but were never significantly correlated when the MC method was used. Discounting across the five outcomes produced a two-factor solution when the FITB data were factor analyzed. The MC data were described by a one-factor solution. The present results illustrate that procedural variables have a potentially profound impact on delay-discounting data, and generalizing from studies on delay discounting should be done with caution until those variables are fully understood.     

Delay Discounting as a Function of Intrinsic/Extrinsic Religiousness,Religious Fundamentalism,and Regular Church Attendance

Delay discounting occurs when the subjective value of an outcome decreases because its delivery is delayed. Previous research has suggested that the rate at which some, but not all, outcomes are discounted varies as a function of regular church attendance. In the present study, 509 participants completed measures of intrinsic religiousness, extrinsic religiousness, religious fundamentalism, and whether they regularly attended church services. They then completed a delay-discounting task involving five outcomes. Although religiousness was not a significant predictor of discounting for all outcomes, participants scoring high in intrinsic religiousness tended to display less delay discounting than participants scoring low. Likewise, participants scoring high in religious fundamentalism tended to display more delay discounting than participants scoring low. These results partially replicate previous ones in showing that the process of discounting may vary as a function of religiousness. The results also provide some direction for those interested in altering how individuals discount.     

Induction when rats lick for 1% liquid-sucrose reinforcement

Previous research reported that rats responding for 1% liquid-sucrose reinforcement when 32% sucrose reinforcement is upcoming will decrease their response rate (contrast) if licking is the dependent measure and increase their response rate (induction) if pressing a lever is the dependent measure. The present study investigated whether induction could be observed when licking served as the dependent measure and whether induction in lever pressing and contrast in licking behaviour could be concurrently observed. Experiment 1 found induction when rats licked to earn the rewards but consumed them at a location separate from the spout licked to earn them. Experiment 2 also found induction when rats earned (and consumed) rewards by licking the same spout throughout the session. Experiment 3 separately measured instrumental lever pressing for sucrose rewards and licking the sucrose during the reward period. We found that both measures increased for 1% sucrose when 32% sucrose reinforcement was upcoming. The present results indicate that the type of response is not the sole determinant of whether contrast or induction is observed. Rather, they suggest that other procedural details, such as the location of reinforcer delivery, influence which effect is observed. The results also indicate that associative processes underlie the appearance of induction in responding for 1% sucrose.     

Rats’ Response Rates for 1 % Sucrose When Food-Pellet Reinforcement is Upcoming: Effect Of Upcoming Reinforcement Contingency

The Psychological Record - Previous research has demonstrated that rats’ rates of lever pressing for 1% liquid-sucrose reinforcers in the first half of a 50-min session increase when...     

The effect of type of behavior on behavior change caused by type of upcoming food substance

Previous research suggests that rats will decrease their consumption of a low-valued substance if a high-valued one will soon be available (anticipatory contrast), but will increase their rate of operant responding for a low-valued substance if a high-valued one will soon be available (positive induction). The present experiments tested whether rats would increase their operant rate of licking or lever pressing for 1% liquid-sucrose reinforcement when 32% sucrose reinforcement was upcoming in the same session. Results indicated that upcoming 32% sucrose increased rates of lever pressing for 1% sucrose, but did not produce similar increases in rates of licking. In fact, upcoming 32% sucrose significantly reduced lick rates in Experiment 2. The present results suggest that the different changes in behavior may be linked to the specific response that the subjects must engage in to obtain the reward (i.e., licking vs. lever pressing), and not to the function of the behavior (i.e., consummatory vs. operant) or to how frequently the substances are available (i.e., continuously vs. intermittently).     

Investigating the illusion of control in mildly depressed and nondepressed individuals during video-poker play

Cognitive fallacies, such as the illusion of control, and psychological disorders, such as depression, may perpetuate gambling and thus contribute to problem gambling (e.g., R. Ladouceur, C. Sylvan, C. Boutin, & C. Doucet, 2002). Gender differences may exist across these variables (e.g., N. M. Petry, 2005). The authors investigated these possibilities by recruiting mildly depressed and nondepressed individuals to play jacks or better, 5-card draw, video poker. Across three poker sessions, participants were given (a) no choice of which cards to play, (b) information on the best cards to play but control over which cards were played, or (c) no information and complete control over which cards were played. The total amount of money gambled increased as control over the game decreased, but this result correlated with an increase in the rate of play. Depressed and nondepressed participants did not differ in how they gambled, but men gambled significantly more and sometimes made more mistakes during play than did women. These results question the role of the illusion of control and depression in perpetuating gambling. They also suggest that providing players information about which cards to play may indirectly promote gambling and provide insight as to why men are more prone to suffer from gambling problems than are women.