A fragile effect: The influence of episodic memory on delay discounting.

Delay discounting occurs when a reward loses value as a function of delay. Episodic future thinking (EFT) reliably decreases delay discounting. EFT may share cognitive features with recalling episodic memories such as constructive episodic simulation.

An experimental approach: Investigating the directive function of autobiographical memory.

Why do we have autobiographical memory and how is it useful? Researchers have proposed a directive function; our experiences guide our behavior, particularly when faced with an open-ended problem. Two experiments (one between-participant and one mixed design) were therefore conducted to test whether success autobiographical memories - any experience when the participant felt successful and competent - are helpful for generating solutions to problem scenarios. One research aim was to experimentally test the directive function as current experimental evidence is limited and results are mixed.

Reduced access to reinforcement drives delay discounting during experienced delays.

Rewards lose value as a function of delay. Previous studies suggest that delays have a bigger effect on reward value when people must wait during the delay. However, whether delays involve waiting or postponing has often been confounded with whether choices are about hypothetical or real rewards.

Preweaning environmental enrichment alters neonatal ultrasonic vocalisations in a rat model for prenatal infections.

Objective: Maternal infections are a well-known risk factor for neurodevelopmental defects. Such defects are associated with a range of symptoms, and environmental enrichment (EE) could be a promising approach to rehabilitate these. We used the well-established prenatal poly I:C (polyinosinic-polycytidylic acid) model in rats to examine the effects of preweaning EE on rat pups' ultrasonic vocalisations (USVs) when separated from their mothers.

Choices about whether to wait: Changes in delay discounting without changes in time perception.

Delay discounting occurs when the present, subjective value of a reward decreases as a function of delay. Delay discounting is steeper when individuals must wait during the delay, and delay discounting rates for decisions about waiting are not strongly correlated with those for decisions about postponing without waiting. We examined whether changes in delay discounting in choices about waiting are linked to changes in subjective time perception.

In Search of the Preference Reversal Zone.

A preference reversal is observed when a preference for a larger-later reward over a smaller-sooner reward reverses as both rewards come closer in time. Preference reversals are common in everyday life and in the laboratory and are often claimed to support hyperbolic delay-discounting models which, in their simplest form, can model reversals with only one free parameter. However, it is not clear if the temporal location of preference reversals can be predicted a priori.

Recently encountered delay lengths produce contrast effects on delay discounting.

People demonstrate shallower delay discounting when they have recently made decisions about smaller amounts of money than when they have recently made decisions about larger amounts of money. That is, recent reward amounts produce a contrast effect on delay discounting. We tested whether a similar contrast effect occurs for delays.

Investigating food preference in zoo-housed meerkats.

Understanding food preference among animals in human care can support improvements to welfare through training and day-to-day care (e.g., diet management).

Assessing potential reinforcement-like effects of brief stimuli unrelated to food reinforcers.

It is widely assumed that reinforcers are biologically relevant stimuli, or stimuli that have been associated with biologically relevant stimuli. However, brief, arbitrary stimuli have also been reported to have reinforcement-like effects, despite being unrelated to biologically relevant stimuli like food. The present study explored the potential reinforcement-like effects of brief stimuli across 5 experiments.

The Effects of Machine Balance and Free-Spins Features on Machine Preference and Bet Amounts.

Across two experiments, the current study investigated whether the balance displayed on slot-machine screens affects gamblers' decision making in a manner similar to the "house-money effect" observed in other gambling modes. The balance indicates the total amount the gambler has available to wager from. We manipulated initial slot-machine balance within a simulated slot-machine task.

Prevention of the development of problem behavior: A laboratory model.

Few studies have isolated the preventive efficacy of common behavioral strategies like noncontingent reinforcement (NCR) and differential reinforcement of alternative behavior (DRA). The purpose of the current study was to develop and evaluate a laboratory model of these two problem behavior prevention strategies. Undergraduate students participated in a computer simulation, in which clicks to a designated area of the computer screen were analogous to the emergence of problem behavior.

Differential effects of 3,4-methylenedioxymethamphetamine, methamphetamine, meta-Chlorophenylpiperazine, and scopolamine on behavioral repetition versus variation in rats.

Acute administration of drugs of abuse, such as MDMA and methamphetamine, disrupts performance on many operant tasks, for example, those used to study memory. This might occur in part because drugs make behavior, in general, more repetitive or more variable, or because they produce a more global disruption to performance. The current study explored this across two experiments by employing Neuringer's 'reinforced variability' procedure.

Realistic Free-Spins Features Increase Preference for Slot Machines.

Despite increasing research into how the structural characteristics of slot machines influence gambling behaviour there have been no experimental investigations into the effect of free-spins bonus features-a structural characteristic that is commonly central to the design of slot machines. This series of three experiments investigated the free-spins feature using slot machine simulations to determine whether participants allocate more wagers to a machine with free spins, and, which components of free-spins features drive this preference. In each experiment, participants were exposed to two computer-simulated slot machines-one with a free-spins feature or similar bonus feature and one without.

The effect of MDMA on sensitivity to reinforcement rate.

Administration of (±)3,4-methylenedioxymethamphetamine (MDMA) causes memory errors by increasing proactive interference. This might occur because MDMA alters sensitivity to reinforcement. The current 2 experiments investigated this directly by assessing the acute (Experiment 1) and chronic (Experiment 2) effects of MDMA on sensitivity to reinforcement.

The effect of reinforcer magnitude on probability and delay discounting of experienced outcomes in a computer game task in humans.

Delay and uncertainty of receipt both reduce the subjective value of reinforcers. Delay has a greater impact on the subjective value of smaller reinforcers than of larger ones while the reverse is true for uncertainty. We investigated the effect of reinforcer magnitude on discounting of delayed and uncertain reinforcers using a novel approach: embedding relevant choices within a computer game.

The disruptive effects of methamphetamine on delayed-matching-to-sample performance reflect proactive interference and are reduced by SCH23390.

Different drugs produce different patterns of impairment on delayed matching-to-sample tasks. For example, (+/-)3,4-methylenedioxymethamphetamine (MDMA) produces an increase in proactive interference. That is, subjects are less accurate when they are required to make a response different to the one they made on the immediately previous trial.

Optimal and nonoptimal choice in a laboratory-based sunk cost task with humans: a cross-species replication.

The current four experiments examined the sunk cost effect-nonoptimal persistence following investment-in a laboratory-based decision-making task with adult humans. Subjects made repeated decisions about whether to persist in a course of action-a fixed-ratio schedule whose response requirements varied unpredictably from one trial to the next-or to abandon it and escape in favor of a new trial with a potentially smaller fixed ratio schedule. Satisfying the ratio requirement produced a brief video clip from a preferred television program.

The sunk cost effect with pigeons: some determinants of decisions about persistence.

The sunk cost effect occurs when an individual persists following an initial investment, even when persisting is costly in the long run. The current study used a laboratory model of the sunk cost effect. Two response alternatives were available: Pigeons could persist by responding on a schedule key with mixed ratio requirements, or escape by responding on a second key.

Providing a reinforcement history that reduces the sunk cost effect.

The sunk cost error occurs when individuals persist with a non-optimal course of action because they have already invested time or resources in it. The current study examined the effect of specific experiences on the likelihood of the sunk cost error. Six pigeons were given repeated choices between persisting with and escaping from relatively large fixed ratios.

Tolerance to cocaine's effects on schedule-controlled behavior: role of delay between pause-ending responses and reinforcement.

The schedule of reinforcement under which behavior is maintained is an important contributor to whether tolerance to the behavioral effects of cocaine develops. Schedule parameter value (for example, fixed-ratio size) has been shown to affect the development of tolerance under some schedule types but not others, but the specific procedural variables causing this effect remain to be identified. To date, schedule-parameter-related tolerance has developed when a longer pause after reinforcement does not lead to a shorter delay between the response that ends the pause and reinforcement.