Elbert Blakely

Function-altering effects of contingency-specifying stimuli.

Contingengy-specifying stimuli (CSSs) can function differently than discriminative stimuli. Rather than evoking behavior due to a history of discrimination training, they alter the function of other stimuli and, therefore, the behavioral relations involving those stimuli. CSSs can alter the evocative function of discriminative stimuli, establishing operations, and conditional stimuli, as well as the efficacy of reinforcing and punishing stimuli and of stimuli that can function in second-order respondent conditioning. The concept of function-altering CSSs has implications for such areas of interest as stimulus equivalence, the terminology involving “rules” and “rule-governed behavior,” and the way in which behavior analysts view the effects of such basic processes as reinforcement and punishment.

Evolution and Behavior

On June 19, 1987, the United States Supreme Court, by a 7–2 vote, struck down as unconstitutional a Louisiana act requiring its teachers to devote equal time to “creation science” if they discussed evolution in their classes. This case, which was well publicized, is but one in a long series of legal battles over the teaching of evolution in public schools. Those battles are instructive in demonstrating the great reluctance with which scientific fact is accepted when it conflicts with traditional belief. And make no mistake about it, that evolution occurred is a fact. Consistent observations and inferences by the thousands indicate that, as Stephen Jay Gould (1987–1988) affirmed: The earth is billions of years old and its living creatures are linked by ties of evolutionary descent. Scientists stand accused of promoting dogma by so stating, but do we brand people illiberal when they proclaim that the earth is neither flat nor at the center of the universe. Science has taught us some things with confidence! Evolution on an ancient earth is as well established as our planet’s shape and position. Our continuing struggle to understand how evolution happens (the “theory of evolution”) does not cast our documentation of its occurrence—the “fact of evolution”—into doubt, (p. 186)

The Differential Outcomes Effect

The differential outcomes effect refers specifically to the increase in speed of acquisition or terminal accuracy that occurs in discrimination training when each of two or more discriminative stimuli is correlated with a particular outcome (e.g., type of reinforcer). The present review summarizes studies concerned with the differential outcomes effect, provides a behavioral analysis of the phenomenon in terms of operant-respondent interactions, and offers suggestions for future research.

Rules: Function-altering contingency-specifying stimuli

Behavior analysts have traditionally defined rules as discriminative stimuli. Three problems with this interpretation are discussed. First, because the effects of rules are often delayed, and the effects of discriminative stimuli are immediate, classifying rules as discriminative stimuli violates the definitional requirements of the latter. Second, when rules are defined as discriminative stimuli, other truly unique effects of rules may be obscured. Finally, both rules and contingencies develop new behavioral relations; however, when rules are interpreted as discriminative stimuli, their effects are not readily compared with those of contingencies. As an alternative, we suggest that rules be interpreted as function-altering contingency-specifying stimuli. Implications of this function-altering interpretation for terminology and research strategy are discussed.

The effects of delayed reinforcement and a response-produced auditory stimulus on the acquisition of operant behavior in rats

The present experiment examined the effects of different delays of food delivery with and without a response-produced auditory stimulus on the acquisition of a spatially defined operant in rats. The operant was breaking a photoelectric beam located near the ceiling at the rear of the experimental chamber. In five groups of experimentally naive rats, the effects on photobeam-break responses of two different reinforcement delays (4 s and 10 s) with and without a response-produced auditory stimulus were compared during eight 1-hr sessions. In one control group (0-s delay), an immediate (i.e., 0.25-s) reinforcement contingency was in effect and in another control group (no food), responses were measured in the absence of any reinforcement contingencies. Results showed that rates of acquisition and responding were higher with shorter reinforcement delays and when there was a response-produced auditory stimulus. These results extend previous findings showing that neither direct shaping nor immediate reinforcement is necessary for operant conditioning. However, the present results demonstrate that the speed and extent of conditioning depends on the temporal relation between the response and the reinforcer. The findings are discussed in terms of a conditioned reinforcement analysis of the stimuli produced by operant responses.

A Descriptive Taxonomy of Environmental Operations and Its Implications For Behavior Analysis

Environmental operations may be classified according to whether they have evocative or function-altering effects. Evocative events, such as the presentation of unconditioned and conditioned stimuli, establishing operations, and discriminative stimuli, serve to increase, decrease, or maintain the momentary frequency of behavior. Function-altering operations, such as operant and respondent conditioning, the correlation of stimuli, and the presentation of certain verbal stimuli, serve to increase, decrease, or maintain the evocative and function-altering (e.g., reinforcing or punishing) functions of other events. This paper expands upon the functional taxonomy of environmental events described by Michael (1993a). The resulting classification scheme should permit behavior analysts to more easily respond to similarities and differences between functional environmental events. This paper discusses implications of the suggested taxonomy for how behavior analysts talk about motivational variables, discriminative stimuli, the operant unit of analysis, and the distinction between operant and respondent conditioning.

Chronic effects of clonazepam, phenytoin, ethosuximide, and valproic acid on learning in pigeons as assayed by a repeated acquisition procedure

The acute and chronic effects of the antiepileptic drugs clonazepam (0.06, 0.13, and 0.25 mg/kg), phenytoin (2.5, 5, and 7.5 mg/kg), ethosuximide (40, 80, and 120 mg/kg), and valproic acid (40, 80, and 120 mg/kg) were evaluated in pigeons responding under a repeated acquisition procedure. At certain doses, acute administrations of all drugs impaired learning (i.e., increased errors) and reduced rate of responding. Appreciable tolerance developed to these effects with chronic exposure, although the physiological mechanism responsible for this outcome is unknown.

Defining terms in behavior analysis: Reinforcer and discriminative stimulus.

Many definitions of reinforcer and discriminative stimulus found in behavioral texts include a requirement of temporal proximity between stimulus and response. However, this requirement is not consistently adopted. We present additional evidence from a questionnaire that was sent to members of the editorial boards of several behavioral journals showing that there is not universal agreement concerning the temporal parameters accepted in the definitions of reinforcer and discriminative stimulus. We suggest that the disagreement over the definitions of these essential terms ought to be at least addressed if not resolved. Because the discrepancy usually occurs when the behavior of verbal humans is at issue, we urge behavior analysts to be conservative when extending the terms reinforcer and discriminative stimulus from the behavior of nonhumans in the laboratory to human behavior where the effects of many stimuli may depend in part on sophisticated verbal repertoires.

Effects of anticonvulsant drugs under automaintenance and negative automaintenance procedures

The behavioral effects of phenytoin, phenobarbital, clonazepam, valproic acid, and ethosuximide were evaluated in food-deprived pigeons performing under automaintenance and negative automaintenance procedures. Under the automaintenance procedure, brief periods of key illumination were followed by food delivery without regard to the subjects behavior. In most instances, when drugs were not given this procedure engendered high rates of keypecking during almost all key illuminations (trials). Acute administrations of phenytoin (10-20 mg/kg), valproic acid (40-120 mg/kg), and ethosuximide (40-120 mg/kg) produced generally dose-dependent decreases in percent trials with a response and rate of responding. Although phenobarbital (30-60 mg/kg) and clonazepam (2.5-7.5 mg/kg) produced little obvious effect on percent trials with a response, these drugs generally increased rate of responding. Under the negative automaintenance procedure, food delivery followed only key illuminations during which keypecking did not occur. Keypecking occurred at a low rate under this procedure, with no responses occurring during the majority of key illuminations. Thus, this procedure appeared to involve responding elicited by respondent conditioning but suppressed by the response-dependent omission of food. Across the same dose ranges evaluated under the automaintenance procedure, clonazepam and phenobarbital generally increased percent trials with a response and rate of responding in dose-dependent fashion. Phenytoin similarly increased percent trials with a response but had little consistent effect on rate of responding. Ethosuximide and valproic acid failed to affect responding under this procedure.

Human Performance Under Sequences of Fixed-Ratio Schedules: Effects of Ratio Size and Magnitude of Reinforcement

In a discrete-trials procedure, adult humans chose between two sequential fixed-ratio (FR) schedules. Points, later exchangeable for money, were given for the completion of each FR. When each sequence produced two points for an equal number of responses overall, the value of the first FR in a sequence did not affect choice. When the values of the first FR in each sequence were equal, subjects preferred the alternative with the smaller second FR. Once a preference was established for the alternative with the smaller overall response requirement, two points were given for completing the second FR of the nonpreferred sequence. This sequence then provided three total points. Preference immediately shifted to the alternative requiring more responses overall (and per point) but offering more points.