Early-extinction effects on a force response of humans.

Humans were used to investigate changes in response force occurring soon after reinforcement was eliminated. In Experiment 1, in a 300-s baseline phase, 10 participants received a point for holding down a pressure sensor set to operate at a force equal to 85% of the maximum force the participants exerted during a pretest. Following this, during a 600-s extinction phase, criterion responses had no consequence.

Context affects resurgence of negatively reinforced human behavior.

The effects of context on the resurgence of negatively reinforced (escape) responding was studied in an experiment with undergraduate students in which resurgence and renewal procedures were combined. Across conditions, in baseline (BL), key-pressing produced 3-s timeouts from pressing a force cell on a variable-ratio schedule of reinforcement; in the Alternative-Reinforcement and Test phases, a differential-reinforcement-of-other-behavior schedule and extinction were in effect, respectively. Conditions differed according to the context (the computer-screen color) in effect in each phase: ABA vs.

Effects of reinforcement value on instruction following under schedules of negative reinforcement.

The effects of reinforcement value and social control on instruction following under a negative-reinforcement (escape) schedule were studied. Initially, responding produced timeouts from pressing a force cell under a low and a high force requirement on a fixed-ratio 1 schedule of reinforcement. Next, participants were reexposed to the low and high force requirements, but were instructed that the experimenter expected them to decrease the number of timeouts relative to the previous exposures to the procedure.

The effects of instructions on the sensitivity of negatively reinforced human behavior to extinction.

The effects of instructions on the sensitivity of negatively reinforced (escape) behavior to extinction were studied. Initially, responding produced timeouts from pressing a force cell on a variable-ratio (VR) schedule, which was then discontinued (extinction). Based on extinction data, participants were distributed into two groups.

The recurrence of negatively reinforced responding of humans.

The recurrence of negatively reinforced responding of humans was studied in three experiments. In each experiment during Baseline, key-pressing produced 3-s timeouts from a requirement to exert finger pressure on a force cell according to variable- or fixed-ratio schedules of reinforcement. In Experiment 1, resurgence was studied by arranging a differential-reinforcement-of-other-behavior schedule in the second phase, and extinction in the Test phase.

Human choice under schedules of negative reinforcement.

The generalized matching equation provides a good description of response allocation in concurrent schedules of positive reinforcement in nonhumans as well as in humans. The present experiment was conducted to further investigate the allocation of responding under concurrent schedules of negative reinforcement (i.e.

Timeout from a high-force requirement as a reinforcer: an effective procedure for human operant research.

A procedure to study human operant conditioning is described using a timeout from a high-force requirement as reinforcer when a high force response was required. Experiment 1 reported evidence that a timeout from a high-force requirement acted as a reinforcer and a second experiment demonstrated sensitivity to delay to escape from the force requirement as a parameter of choice in a self-control paradigm. The results of the two experiments indicate a functional similarity between unconditioned reinforcers (e.

Choices between segmented and unsegmented schedules and the self-control paradigm.

A concurrent-chains procedure was used to examine choice between a segmented (two- or three-terminal-link segments schedules) and an unsegmented schedule (simple schedule) in terminal links with equal interreinforcement intervals. In most such experiments, preference for the unsegmented schedule has been found, but in a recent study with humans (Alessandri et al., 2010) a reversal in preference was found when, in the segmented schedule, the terminal link segmenting stimulus was presented briefly and closer to food delivery such that the early terminal link stimulus was temporally closer to the food delivery.

Subjective time: cognitive and physical secondary tasks affect timing differently.

Humans were trained on a temporal discrimination to make one response when the stimulus duration was short (2 s) and a different response when the stimulus duration was long (8 s). They were then tested with stimulus durations in between to determine the bisection point. In Experiment 1, we examined the effect of a secondary cognitive task (counting backwards by threes) on the bisection point when participants were trained without a cognitive load and were tested with a cognitive load or the reverse (relative to appropriate controls).

Preference for a segmented schedule using a brief S+ stimulus correlated with a great delay reduction in humans.

Past studies using the concurrent-chain procedure showed that pigeons and humans generally prefer an unsegmented schedule to a segmented schedule. This finding is ostensibly inconsistent with theories of conditioned reinforcement such as delay-reduction theory. In the present study with humans, two changes in the basic segmented schedule were implemented to resolve this inconsistency.

Preference for 50% reinforcement over 75% reinforcement by pigeons.

When pigeons are given a choice between an initial-link alternative that results in either a terminal-link stimulus correlated with 100% reinforcement or a stimulus correlated with 0% reinforcement (overall 50% reinforcement) and another initial-link alternative that always results in a terminal-link stimulus correlated with 100% reinforcement, some pigeons show a preference for the initial-link alternative correlated with 50% reinforcement. Using this procedure, in Experiment 1, we found a relatively modest preference for 100% over 50% reinforcement. In Experiment 2, we decreased the reinforcement density for the second initial-link alternative to 75% and found a significant preference for the 50% reinforcement initial-link alternative.

Within-trial contrast: The effect of probability of reinforcement in training.

There is evidence that pigeons prefer conditioned reinforcers that are preceded by greater effort over those that are preceded by less effort (an effect that has been attributed to within-trial contrast). In past research the probability of reinforcement for correct choice of the conditioned reinforcer has been 100%, however, the high level of reinforcement for both alternatives in training may result in a performance ceiling when choice between those alternatives is provided on test trials. In the present study we tested this hypothesis by including a group for which the probability of reinforcement in training was only 50%.

Preference for rewards that follow greater effort and greater delay.

Humans prefer (conditioned) rewards that follow greater effort (Aronson & Mills, 1959). This phenomenon can be interpreted as evidence for cognitive dissonance (or as justification of effort) but may also result from (1) the contrast between the relatively greater effort and the signal for reinforcement or (2) the delay reduction signaled by the conditioned reinforcer. In the present study, we examined the effect of prior force and prior time to produce stimuli associated with equal reinforcement.

Cognitive dissonance in children: justification of effort or contrast?

Justification of effort is a form of cognitive dissonance in which the subjective value of an outcome is directly related to the effort that went into obtaining it. However, it is likely that in social contexts (such as the requirements for joining a group) an inference can be made (perhaps incorrectly) that an outcome that requires greater effort to obtain in fact has greater value. Here we present evidence that a cognitive dissonance effect can be found in children under conditions that offer better control for the social value of the outcome.