No abstract

Differential-reinforcement-of-low-rate (DRL) schedules are used to decrease the overall rate of, but not eliminate, a target response. Two variations of DRL, spaced-responding and full-session, exist. Preliminary comparative analyses suggest that the two schedules function differently when unsignaled. We compared response rates under these two DRL variations with and without signals. In Experiment 1, five preschool students played a game in which points were earned under DRL schedules. In some sessions, a stimulus signaled when responses would be reinforced (S+) or not reinforced (S-). In others, only an S-was present. Signals (S+/S-) facilitated and maintained responding in both types of DRL schedules. In Experiment 2, we modified the signals with five different preschoolers. Instead of an S-only, we did not present any signals. Elimination and high variability of the target response were observed with the S-only and absence of S +/S-, respectively. Signaled DRL schedules are recommended for application.

The American Academy of Pediatrics (AAP) recommends that infants spend supervised time in the prone (tummy) position to foster motor development and prevent cranial deformities. However, infants may not tolerate the position, and consequently, caregivers may avoid placing their infants in the prone position. The AAP recommends that caregivers provide toys or interaction during tummy time. We evaluated the individual and combined effects of a play mat and experimenter interaction on negative vocalizations and head elevation during tummy time-positive effects were limited. Next, we evaluated a parent-led intervention wherein mothers interacted with their infants, using a toy, while lying chest-to-chest. This intervention was associated with a reduction in negative vocalizations and an increase in head elevation for the majority of infants. Additionally, mothers rated the effectiveness of the parent-led intervention more favorably than the experimenter-led intervention, suggesting the effects of the parent-led intervention were also socially valid.

Transitions from one activity to another may evoke problem behavior from individuals with intellectual disabilities. One explanation for the occurrence of problem behavior could be the change in relative densities of reinforcement between the two activities. We conducted a descriptive assessment of problem behavior with four children during transitions to and from several different contexts. We observed that, in most cases, the probability of problem behavior was greater during a transition to an activity with a lower density of reinforcement than during a transition to an activity with a higher density of reinforcement. We discuss our findings in terms of problem behavior associated with transitions in activities with different reinforcer densities, as well as the possibility that the problem behavior may be associated with shifts in motivating operations.

Generally, immediate outcomes are preferred to delayed outcomes, and in economics, this phenomenon is referred to as positive time preference. If positive time preference is normative, when asked to schedule a set of outcomes, a person should typically prefer a worsening sequence (i.e., choose to start with the best outcome and end with the worst outcome). Several studies have shown that when a choice is among a sequence of outcomes, people typically exhibit negative time preference (i.e., they prefer an improving series of events). In the current studies, college students responded to hypothetical questions via an online survey. Study 1a was a replication and extension of procedures described by Loewenstein and Prelec (1991, Section II). Response patterns like those of Loewenstein and Prelec were observed in that the percentage of participants who saved the best for last decreased when the interval between activities in the sequence increased. In Study 1b, participants were surveyed about their preference for the order in which they would experience hypothetical outcomes with sequences of different sizes (e.g., three activities to sequence or eight). As array size increased, the percentage of participants who saved the best for last, or generated a perfectly improving sequence, decreased. In Study 2, 192 college students responded to questions involving categorically different outcomes (e.g., noxious stimuli, food, exercise, schoolwork, leisure) via an online survey. A smaller percentage of participants saved the best for last relative to prior studies, but the percentage was highest when sequences involved noxious stimuli or food.