Choice and reinforcement delay

Previous studies of choice between two delayed reinforcers have indicated that the relative immediacy of the reinforcer is a major determinant of the relative frequency of responding. Parallel studies of choice between two interresponse times have found exceptions to this generality. The present study looked at the choice by pigeons between two delays, one of which was always four times longer than the other, but whose absolute durations were varied across conditions. The results indicated that choice is not uniquely determined by the relative immediacy of reinforcement, but that absolute delays are also involved. Models for concurrent chained schedules appear to be more applicable to the present data than the matching relation; however, these too failed to predict choice for long delays.     

First‐time mothers in home visitation services utilizing child development specialists

Professionals in the field of child development were employed to provide home visitation services to 156 mothers and infants prenatally through the infants' first birthdays. Compared to a control group of mothers (n = 107), the intervention mothers utilized more community resources, had safer homes, had more appropriate developmental expectations, had better understanding of noncorporal punishment, and had behaviors that were more accepting and respectful to their infants. The home visitors were well educated, with experience in home visitation, and supervised. Program implementation procedures were documented and supervised. Program fidelity and the efficacy of using child development specialists as home visitors are discussed in regards to the positive findings. ©2004 Michigan Association for Infant Mental Health.     

Functional analysis and treatment of human-directed undesirable behavior exhibited by a captive chimpanzee

A functional analysis identified the reinforcer maintaining feces throwing and spitting exhibited by a captive adult chimpanzee (Pan troglodytes). The implementation of a function-based treatment combining extinction with differential reinforcement of an alternate behavior decreased levels of inappropriate behavior. These findings further demonstrate the utility of function-based approaches to assess and treat behavior problems exhibited by captive animals.     

A mingled yarn

The behavior of nonliving and living systems is generally viewed as being qualitatively different. The key difference is often summarized by saying that whereas living systems are complex, nonliving ones are simple. This distinction is often the basis for claiming essential differences in conceptual stances, methods, and theories between scientific fields. I argue first that nonliving systems can display the unpredictable, irreducible, irreversible, and emergent-in sum, complex-properties of living systems. Then I discuss an emerging field called complexity theory, the principles of which offer the promise of bringing quantitative unity to an enormous range of phenomena, living or dead.