The control of responding by sounds: unusual effect of reinforcement.

Naive rats were trained to respond on one lever in the presence of noise bursts from one speaker and on a second lever in the presence of noise bursts from a second speaker. The speakers were mounted behind the levers. When responding on the lever adjacent to the sounding speaker was reinforced, control developed within fewer than five trials. When responding on the nonadjacent lever was selectively reinforced, responding on the lever adjacent to the sounding speaker increased in probability for several sessions. Naive rats were trained to respond on the nonadjacent lever following preexposure to the sound. Responding on the lever adjacent to the sounding speaker increased in probability, showing that novelty was not responsible for the effect. Naive rats were run on automaintenance procedures in which there was no explicit pairing of sound and magazine operation, 100% pairing of sound and magazine operation, or magazine operation following 40% of sound presentations. None of the rats acquired the response of approaching and sniffing the sounding speaker, indicating that sound-magazine pairing was not responsible for the effect.     

Discrimination training, partial reinforcement, and increases in intertrial interval all reduce response speed in a continuously reinforced key-pecking task

Pigeons were trained in a discrete-trial task in which a response to the center key obtained illumination of a side key and a single response to the side key terminated a trial with either reinforcement or nonreinforcement. Center-key speeds (i.e., reciprocals of latencies) declined with increases in intertrial interval, and it is argued that this effect is related to a decreased likelihood as intertrial interval increases that birds will be near the key at trial onset. Side-key speeds on trials with reinforcement decreased both with increases in intertrial interval and with shifts from continuous reinforcement to either a discrimination or a partial-reinforcement condition. The effects on side-key speeds are compared with effects observed in alley-running tasks using rats, and an interpretation in terms of frustration theory is offered for the results obtained in both types of task.     

The relationship between pronunciation and listening discrimination when Japanese natives are learning English

Two Japanese students were taught to pronounce and discriminate English words that contain unfamiliar phonemic contrasts (e.g., rock and lock). Teaching pronunciation was found to be easier than teaching listening discrimination. Teaching listening discrimination resulted in collateral improvement in pronunciation and, to a lesser extent, vice versa.     

In Defense of Affirmative Action

Affirmative action refers to positive steps taken to hire persons from groups previously and presently discriminated against. Considerable evidence indicates that this discrimination is intractable and cannot be eliminated by the enforcement of laws. Numerical goals and quotas are justified if and only if they are necessary to overcome the discriminatory effects that could not otherwise be eliminated with reasonable efficiency. Many past as well as present policies are justified in this way.     

Categorization of natural movements by pigeons: visual concept discrimination and biological motion

In three experiments, pigeons were exposed to a discriminated autoshaping procedure in which categories of moving stimuli, presented on videotape, were differentially associated with reinforcement. All stimuli depicted pigeons making defined responses. In Experiment 1, one category consisted of several different scenes of pecking and the other consisted of scenes of walking, flying, head movements, or standing still. Four of the 4 birds for which pecking scenes were positive stimuli discriminated successfully, whereas only 1 of the 4 for which pecking was the negative category did so. In the pecking-positive group, there were differences between the pecking rates in the presence of the four negative actions, and these differences were consistent across subjects. In Experiment 2, only the categories of walking and pecking were used; some but not all birds learned this discrimination, whichever category was positive, and these birds showed some transfer to new stimuli in which the same movements were represented only by a small number of point lights (Johansson's “biological motion” displays). In Experiment 3, discriminations between pecking and walking movement categories using point-light displays were trained. Four of the 8 birds discriminated successfully, but transfer to fully detailed displays could not be demonstrated. Pseudoconcept control groups, in which scenes from the same categories of motion were used in both the positive and negative stimulus sets, were used in Experiments 1 and 3. None of the 8 pigeons trained under these conditions showed discriminative responding. The results suggest that pigeons can respond differentially to moving stimuli on the basis of movement cues alone.     

Limited matching on concurrent-schedule reinforcement of academic behavior

Three adolescent students with special educational needs were given a choice between completing one of two available sets of math problems. Reinforcers (nickels) across these alternatives were arranged systematically in separate experimental phases according to three different concurrent variable-interval schedules (reinforcement ratios of 2:1, 6:1, and 12:1). Time allocated to the two stacks of math problems stood in linear relationship to the reinforcement rate obtained from each stack, although substantial undermatching and bias were observed for all subjects. However, changes in the schedules were not followed by changes in allocation patterns until adjunct procedures (e.g., changeover delays, limited holds, timers, and demonstrations) were introduced. The necessity of adjunct procedures in establishing matching in applied situations is discussed as a limitation to quantitative applications of the matching law in applied behavior analysis.     

A procedure for studying the within-session onset of human drug discrimination.

The purpose of the present study was to develop a procedure for measuring the within-session onset of human drug discrimination. During daily sessions, under double-blind conditions, caffeine-abstinent adults ingested a letter-coded capsule containing 178 mg caffeine or placebo. Trials were presented at 30-s intervals, beginning immediately after drug ingestion and continuing for 60 min. On each trial, subjects could guess which of their two letter-coded drugs they had received by pressing a left button (for one drug) or right button (for the other drug); subjects could also press a center "no guess" button instead of guessing. Each trial ended after one button press. After each session, subjects were told which drug they had received. Subjects earned one point (worth $0.10 per point) for each correct guess. Subjects lost either 0, 1, or 10 points for each incorrect guess; the point-loss contingencies were varied in random order across sessions. Discrimination earnings accumulated across all sessions. The point-loss contingencies decreased random responding and delayed the discrimination time course. Overall, this procedure provided an orderly and relatively continuous measure of the within-session onset of drug discrimination and should have a range of applications in understanding the human behavioral pharmacology of drugs.     

When do errors in reinforcer delivery affect learning? A parametric analysis of treatment integrity

Treatment integrity is the extent to which components of an intervention are implemented as intended (Gresham, 1989). Recent behavior-analytic literature has begun to evaluate the effects of reduced-treatment integrity on the efficacy and efficiency of skill-acquisition interventions. This study extended the current literature on the effects of errors of omission and commission of reinforcer delivery by replicating and extending Hirst and DiGennaro Reed (2015). Using a randomized-control group design, we compared undergraduate student participants' acquisition of conditional discriminations in a parametric analysis of different error values. A computer program erred in reinforcer delivery on 0%, 5%, 10%, 15%, 20%, 25% and 50% of trials. The purpose of the current study was to identify which levels of reduced integrity slowed or prevented acquisition. Our data replicated the findings of Hirst and DiGennaro Reed, and extended parametric analyses by identifying that errors in reinforcer delivery occurring on 15% or fewer trials (i.e., 85% integrity) were unlikely to prevent participants' responding from meeting the mastery criterion. These results could inform future research on how treatment-integrity errors change behavior-analytic procedures and the effects on skill acquisition for consumers of applied behavior analysis.     

外群体一定贬损吗：来自蒙古族和汉族群体的证据

本研究采用单一复述法考察了我国非冲突性、地位平等的蒙古族和汉族群体,在面对面传递彼此不同效价的民族刻板印象信息时的群体效应。实验1证明了蒙古族和汉族间表现出的并非“外群体贬损”,而是“外群体偏爱”。实验2通过考察人际敏感性和群际态度两个变量验证了蒙汉间外群体偏爱的真实性,但这一效应在群际态度消极的高敏感汉族中表现出了人为增益性;而且发现了蒙汉族际沟通中的不同信息传递模式,蒙古族同时着眼于积极和消极信息,而汉族更偏重于积极信息。由此可知,外群体并不一定引发贬损,群体性质兹事体大。