No abstract

The purpose of the present experiment was to evaluate which method, stimulus-stimulus pairing or operant discrimination training, establishes neutral stimuli as more effective conditioned reinforcers, and to explore ways to maintain effects of the stimuli established as conditioned reinforcers. Four rats were exposed to an operant discrimination training procedure to establish a left-situated light as a conditioned reinforcer and to a stimulusstimulus pairing procedure to establish a right-situated light as a conditioned reinforcer. Acquisition of new responses was then arranged to determine how formerly neutral stimuli could maintain responding when the unconditioned reinforcer (water) was presented intermittently in an experimental design similar to a concurrent-chain procedure. During this acquisition, two levers were concurrently available and presses on the left lever produced an operant discrimination trial (left light-response-water), whereas presses on the right lever produced a stimulus-stimulus pairing trial (right light-water). The results suggest that the operant discrimination training procedure was more effective in establishing a neutral stimulus as a conditioned reinforcer and also maintained a higher rate of responding over time.

Stimuli with no specific biological relevance for the organism can acquire multiple functions through conditioning procedures. Conditioning procedures involving compound stimuli sometimes result in blocking, related to the phenomenon of overshadowing. This can affect the establishment of conditioned stimuli in classical conditioning and discriminative stimuli in operant conditioning. The aim of the current experiment was to investigate whether a standard blocking procedure might block the establishment of a conditioned reinforcer-in addition to blocking discriminative control by that stimulus in rats. We used successive discrimination training to establish a tone or a light as a discriminative stimulus for chain pulling, upon which an unconditioned reinforcer (water) was contingent. Next, we trained a tone-light compound stimulus the same way. Finally, we conducted two tests, one for stimulus control and one for a conditioned reinforcing effect on a new response. Little or no discriminative control was evident by the second stimulus, which was added to the previously established discriminative stimulus later during training. The subsequent test showed blocking of conditioned reinforcement in five of the seven rats. Procedures that generate blocking can have a practical impact on attempts to establish discriminative stimuli and/or conditioned reinforcers in applied settings and needs careful attention.

Inappropriate verbal behavior that is labeled "psychotic" is often described as insensitive to environmental contingencies. The purpose of the current study was to establish different classes of rational or appropriate verbal behavior in a woman with developmental disabilities and evaluate the effects on her psychotic or aberrant vocal verbal behavior. Similar to a previous study (Arntzen, Ro Tonnessen, & Brouwer, 2006), the results of the current study suggested that the procedure helped to establish a repertoire of appropriate functional vocal verbal behavior in the participant. Overall, the results suggested the effectiveness of an intervention based on training various classes of verbal behavior in decreasing aberrant verbal behavior.

The present study aimed to investigate the blocking of stimulus control in three children with autism. We used a go/no-go procedure in a standard blocking paradigm. In Phase 1, we established one of two sounds or colored squares as a discriminative stimulus for touching a tablet screen. In Phase 2, a colored square was added to the sound or a sound was added to the colored square in a stimulus compound. The discrimination training continued as in Phase 1. We subsequently tested discriminative control by each of the single stimuli separately and by the compounds. Finally, after testing with no programmed consequences, we reestablished the original discrimination and replicated the test of stimulus control. The results support previous experiments by demonstrating that the establishment of discriminative control by a second stimulus by adding it to a previously established discriminative stimulus in a compound was blocked by the earlier discrimination training in all three participants. We discuss procedural details that may be critical to avoid the blocking of stimulus control in the applied field, particularly with respect to the acquisition of skills that involve multiple stimuli, such as joint attention, social referencing, and bidirectional naming.