Spider-Phobic Children Do Not React with Differential Skin Conductance Responses to Masked Phobic Stimuli

In the present study, spider-phobic children (N = 22) were exposed to subliminal presentations of spiders, snakes, and mushrooms, while skin conductance responses (SCRs) were measured. In addition, pre- and post-treatment symptom severity data were obtained. As a group, spider-phobic children did not react with differential SCRs to masked phobic pictures. In addition, no convincing evidence was found to suggest that individual variation in differential SCRs to phobic stimuli is linked to pre-treatment symptom severity or therapy outcome. These findings cast doubts on the idea that phobics' phenomenal experience of their fear as irrational and uncontrollable is a result of pre-attentive physiological fear activation.     

Effects of d-amphetamine on responding under second-order schedules of reinforcement with paired and nonpaired brief stimuli.

Three pigeons were studied under a multiple schedule in which pecks in each component were reinforced according to a variable-interval 120-s second-order schedule with fixed-interval 60-s units. In the first component of the multiple schedule, the completion of a fixed interval produced either food or a 4-s change in key color plus houselight illumination. In the second component an identical schedule was in effect, but the stimulus was a 0.3-s change in key color. Both long and short brief stimuli were not paired with food presentations in Conditions 1 and 3 and were paired with food in Condition 2. There were no consistent differences in response patterns under paired and nonpaired brief-stimulus conditions when the stimulus was a 4-s change in key color accompanied by houselight illumination. However, pairing the 0.3-s key-color change with food presentations resulted in higher indices of curvature and lower response rates in the early segments of the fixed interval than when the stimulus was not paired with food presentations. Low doses of d-amphetamine (0.3 and 1 mg/kg) produced small and inconsistent increases in overall response rates, and higher doses (3 and 10 mg/kg) decreased overall response rates. d-Amphetamine altered response patterns within fixed intervals by decreasing the indices of curvature and increasing response rates in the early segments of the fixed interval. Response rates and patterns under paired and nonpaired brief-stimulus conditions were not differentially affected by d-amphetamine. Thus, evidence for the enhancement of the conditioned reinforcement effects of psychomotor stimulant drugs was not found with the second-order schedules used in the present study.     

Development and crossmodal transfer of contextual control of emergent stimulus relations

Six normally capable adults first learned three conditional relations in each of two prospective equivalence classes via match-to-sample training with figures as conditional (sample) and discriminative (comparison) stimuli. Then one trained conditional relation in each prospective class was brought under the control of contextual stimuli, two dictated nonsense syllables. Test performances indicated the emergence of untrained conditional relations, and therefore two equivalence classes, that were conditional on the contextual stimuli. These tests involved untrained combinations of contextual stimuli and stimuli in conditional relations, suggesting that the contextual stimuli functioned independently to control conditional relations rather than forming compound stimuli with samples and comparisons in training. Next, two novel figures were made equivalent to each of the original dictated contextual stimuli by match-to-sample training and testing. On subsequent tests, all subjects demonstrated transfer of conditional control of untrained conditional relations from the original auditory contextual stimuli to equivalent visual stimuli. These outcomes further supported the conclusion that the contextual stimuli exerted true conditional control over conditional relations in the equivalence classes and were not merely elements of compound stimuli.     

Increased reinforcement when timeout from avoidance includes access to a safe place

Three experiments investigated the reinforcing value of access to a safe place during timeout from an avoidance schedule. Rats were trained on conjoint schedules in which responding both postponed shock on a free-operant avoidance schedule and produced periods of timeout on fixed-ratio schedules. In some conditions, a shelf was inserted into the operant chamber during timeout, enabling subjects to get off the grid floor. The combination of timeout and shelf maintained substantially higher response rates than the baseline avoidance schedule with ratio requirements as high as 90 (Experiment I). Adding the shelf to timeouts in one component of multiple fixed-ratio schedules of timeout resulted in higher response rates in the component where the shelf was included (Experiment II). When timeouts with and without the shelf were arranged on concurrent schedules, the shelf-timeout combination was preferred, even when of shorter duration than timeout alone (Experiment III). In all three experiments, subjects climbed on the shelf, although all shocks were cancelled during timeout periods. The results could not be accounted for solely in terms of the reinforcing properties of changes in shock rates, but required an interpretation that ascribed conditioned reinforcing value to stimuli associated with such changes.     

Brief exposure to contingent reinforcement produces a sustained increment in the strength of an elicited response.

Squirrel monkeys' lever pressing produced by response-independent shock was measured before, and for an extended period following, exposure to a shock-avoidance procedure. Following avoidance training, the frequency of responding increased by multiples of 10 to 50 across subjects and evidence little or no decrement for up to 6 months of postreinforcement testing. Manual responding produced by intense environmental stimulation may be substantially strengthened by a brief history of reinforcement, such that it is sustained over long periods without reinforcement.     

Escape from serial stimuli leading to food

If the functional relations governing the strength of a conditioned reinforcer correspond to those obtained with other Pavlovian procedures (e.g., Kaplan, 1984), the termination of stimuli appearing early in the interval between successive food deliveries should be reinforcing. During initial training we presented four key colors, followed by food, in a recurrent sequence to each of 6 pigeons. This established a baseline level of autoshaped pecking. In later sessions, we terminated each of these colors or only the first color for a brief period following each peck, replacing the original color with a standard substitute to avoid darkening the key. Pecking decreased in the presence of the last color in the sequence but increased in the presence of the first. In accord with contemporary models of Pavlovian conditioning, these and other data suggest that the behavioral effects of stimuli in a chain may be better understood in terms of what each stimulus predicts, as measured by relative time to the terminal reinforcer, than in the exclusively positive terms of the traditional formulation (Skinner, 1938). The same model may also account for the initial pause under fixed-interval and fixed-ratio schedules of reinforcement.     

THE EFFECTS OF SEQUENTIAL PICTORIAL CUES,SELF-RECORDING,AND PRAISE ON THE JOB TASK SEQUENCING OF RETARDED ADULTS

The present study investigated the effects of a self-recording procedure using sequentially organized picture cues on independent task changes of four mentally retarded adults. Independent task changes were identified as the beginning of new tasks without directives or instruction. In addition to investigating treatment effects, the long-term maintenance of the task-change behavior was measured. During self-recording and picture-cue training, the subjects completed an increased proportion of independent task changes, and this behavior was maintained for more than 10 wk following removal of the training procedures. Self-recording using picture cues was shown to be an effective procedure for teaching mentally retarded adults to function more independently in a job setting.     

Schedule thinning following communication training: using competing stimuli to enhance tolerance to decrements in reinforcer density

Functional communication training (FCT) is a widely used treatment for individuals with developmental disabilities who exhibit severe behavior problems. One inherent challenge of employing FCT as a treatment in the community is that reinforcement for appropriate communication cannot always be immediate or even possible in some circumstances. Of the few studies that have incorporated some form of schedule thinning for communication, most have reported disruption of communication or increases in problem behavior when the schedule of reinforcement is thinned. In the current study, we compared FCT with extinction to FCT with extinction and access to competing stimuli. After conducting a functional analysis, a competing stimulus assessment was performed to identify stimuli that produce reinforcement that ostensibly competes with reinforcement that maintains problem behavior. It was hypothesized that FCT with competing stimuli would result in more stable reductions in problem behavior during schedule thinning, which would ultimately result in quicker achievement of the treatment goal (low levels of problem behavior under the terminal reinforcement schedule for communication) than FCT without competing stimuli. Results confirmed this hypothesis.     

Piagetian conservation of discrete quantities in bonobos (Pan paniscus), chimpanzees (Pan troglodytes), and orangutans (Pongo pygmaeus)

This study investigated whether physical discreteness helps apes to understand the concept of Piagetian conservation (i.e. the invariance of quantities). Subjects were four bonobos, three chimpanzees, and five orangutans. Apes were tested on their ability to conserve discrete/continuous quantities in an over-conservation procedure in which two unequal quantities of edible rewards underwent various transformations in front of subjects. Subjects were examined to determine whether they could track the larger quantity of reward after the transformation. Comparison between the two types of conservation revealed that tests with bonobos supported the discreteness hypothesis. Bonobos, but neither chimpanzees nor orangutans, performed significantly better with discrete quantities than with continuous ones. The results suggest that at least bonobos could benefit from the discreteness of stimuli in their acquisition of conservation skills.     

Teaching children with autism spectrum disorder to tact auditory stimuli: A replication

It is important that tacts are controlled by stimuli across all senses but teaching tacts to children with autism spectrum disorder (ASD) is often limited to visual stimuli. This study replicated and extended a study on the effects of antecedent-stimulus presentations on the acquisition of auditory tacts. We used a concurrent multiple probe across sets design and an embedded adapted alternating treatments design to evaluate acquisition of auditory tacts when auditory stimuli were presented alone (i.e., isolated) or with corresponding pictures (i.e., compound-with-known and compound-with-unknown) with two school-aged boys with ASD. Both participants' responding met the mastery criterion no matter the stimulus presentation with at least one set, but one participant failed to acquire one set of stimuli in the isolated condition. The isolated condition was rarely the most efficient. We conducted post-training stimulus-control probes, and we observed disrupted stimulus control in the isolated condition for one participant. Implications for arranging auditory tacts instruction are discussed.