Preference for mixed versus constant delays of reinforcement: Effect of probability of the short, mixed delay

Preference for mixed versus constant delays of reinforcement was studied with a concurrent-chain procedure. Lever pressing by rats in concurrently available variable-interval 60-second initial links occasionally produced mutually exclusive terminal-link reinforcement delays. A constant delay of reinforcement (either 15 seconds or 30 seconds) composed one terminal link and mixed delays (.2 second and twice the value of the constant delay) were arranged in the other terminal link. The proportion of .2-second delays in the mixed-delay terminal link took on values of 0, .1, .25, .5, .75, .9, and 1.0 over experimental conditions. Based on relative rates of responding in the initial links, preference for the mixed delays was a negatively accelerated function of the proportion of short, mixed delays. Three of five rats preferred the mixed delays to the constant delays when the proportion of short, mixed delays was .1 or higher, and all five rats preferred the mixed delays when the proportion of short, mixed delays was .25 or higher. Neither Squires and Fantino's (1971) delay-reduction model of choice nor a model based on the harmonic mean reinforcement delay provided a close estimate of choice proportions over the range of short-delay proportions studied. The delay-reduction model underestimated choice for the mixed delays at low and intermediate proportions of short delays, and the harmonic-mean-delay model overestimated choice for the mixed delays at intermediate and high proportions of short delays.     

Hill-climbing by pigeons

Pigeons were exposed to two types of concurrent operant-reinforcement schedules in order to determine what choice rules determine behavior on these schedules. In the first set of experiments, concurrent variable-interval, variable-interval schedules, key-peck responses to either of two alternative schedules produced food reinforcement after a random time interval. The frequency of food-reinforcement availability for the two schedules was varied over different ranges for different birds. In the second series of experiments, concurrent variable-ratio, variable-interval schedules, key-peck responses to one schedule produced food reinforcement after a random time interval, whereas food reinforcement occurred for an alternative schedule only after a random number of responses. Results from both experiments showed that pigeons consistently follow a behavioral strategy in which the alternative schedule chosen at any time is the one which offers the highest momentary reinforcement probability (momentary maximizing). The quality of momentary maximizing was somewhat higher and more consistent when both alternative reinforcement schedules were time-based than when one schedule was time-based and the alternative response-count based. Previous attempts to provide evidence for the existence of momentary maximizing were shown to be based upon faulty assumptions about the behavior implied by momentary maximizing and resultant inappropriate measures of behavior.     

Some values guiding community research and action

The dual purposes of applied research-contributing to understanding and improvement-are only partially served by method systems that encourage studying (with increasing precision) a narrow range of questions of modest societal importance. To optimize contributions to challenging societal problems, a field's cherished standards should be adapted to support more adventuresome forms of community research and action. This paper outlines 10 values for community research and action, based on insights from the fields of behavioral and community psychology. These values-reflect the goals and challenges of establishing collaborative relationships with research participants, determining research goals and methods, designing and disseminating interventions, communicating research findings, and advocating for community change. Critical challenges are outlined, and implications for the field and its clients are discussed.     

COMMUNITY INTERVENTION TO DETER ILLEGAL PARKING IN SPACES RESERVED FOR THE PHYSICALLY DISABLED

Illegal use of reserved parking spaces represents a major obstacle to the independence and mobility of people with physical disabilities. Using an ABACACA reversal design, the daily rates of illegal parking in four reserved spaces were examined across three types of sign displays: (a) a vertical sign alone or in combination with (b) a message sign that announced the possibility of public surveillance or (c) a message dispenser device that announced community involvement and dispensed politely worded reminder notes. The average rate of illegal parking dropped from 51.3% during the initial vertical sign phase to 37.3% under the message sign condition, followed by an increase to 50.4% when the message was removed. Illegal parking decreased to 24.5% when the message dispensers were first used (followed by an increase to 57.0% when they were removed) and to 23.7% when the message dispenser condition was repeated. Illegal parking in the final vertical sign condition failed to return to previous levels (M = 37.3%).     

The interaction between stimulus and reinforcer control on remembering.

In a symbolic matching-to-sample task, 6 pigeons obtained food by pecking a red side key when the brighter of two white lights had been presented on the center key and by pecking a green side key when the dimmer of two white lights had been presented on the center key. Across Part 1 and Parts 6 to 10, the delay between sample-stimulus presentation and the availability of the choice keys was varied between 0 s and 25 s. Across Parts 1 to 5, the delay between the emission of a correct choice and the delivery of a reinforcer was varied between 0 s and 30 s. Although increasing both types of delay decreased stimulus discriminability, lengthening the stimulus-choice delay produced a greater decrement in choice accuracy than did lengthening the choice-reinforcer delay. Additionally, the relative reinforcer rate for correct choice was varied across both types of delay. The sensitivity of behavior to the distribution of reinforcers decreased as discriminability decreased under both procedures. These data are consistent with the view, based on the generalized matching law, that sample stimuli and reinforcers interact in their control over remembering.     

Humanizing education: Subjective and objective aspects

I propose that there are four standards to be met if a given educational enterprise is to be considered humane: (1) the practice to be mastered must be socially justified; (2) the disciplines pursued to master the practice must be appropriate to the practice; (3) the practice must be owned by the learner; and (4) this ownership must itself meet certain ethical requirements. The paper emphasizes the problem of ownership. It argues for a view of ownership that is communitarian. This view sees ownership as a function of identification or membership. People become committed to certain educational ends in virtue of the fact that they see themselves as members of a group and the ends as the ends of the group. It is central to this view that ownership of ends does not require full understanding or rational appraisal of such ends. I argue that a rational appraisal of ends is difficult when a novice seeks to appraise the ends of some practice both because the ends of the practice are internal to it in a way that makes grasping such ends difficult prior to mastery of the practice and because initiation into the practice will change the individual's standards of appraisal.     

What is educational theory and how to make it?

An analysis is provided detailing the conditions for the appropriate theoretical study of the object of educational science: pedagogy.     

Relations between neonatal states and 8-month developmental outcome in preterm infants

This study investigated longitudinal relations between measures of neonatal state behavior and developmental outcome in a sample of preterm infants (N = 16). Results indicate that irritability/reactivity in the neonatal period is positively associated with Bayley scores and exploratory play at 8 months. Conversely, neonatal alertness was not associated with these developmental measures. These preliminary findings, based on a small sample, are discussed in the context of preterm function.     

HOW DID MORALITY EVOLVE?

Abstract. This paper presents and criticizes. Alexander's evolutionary theory of morality (1987). Earlier research, on which Alexander's theory is based, is also reviewed. The propensity to create moral systems evolved because it allowed ancestral humans to limit conflict within cooperating groups and thus form larger groups, which were advantageous because of intense between-group competition. Alexander sees moral codes as contractual, and the primary criticism of his theory is that moral codes are not completely contractual but also coercive. Ways of evaluating Alexander's theory as well as modified versions of it are discussed.