Time Outs Research Articles

Reducing Time-Out Assignments for Students with Emotional/Behavioral Disorders in a Self-Contained Classroom

This study assessed the impact of a class-wide time-out/re-directing strategy on (a) the frequency of teacher-assigned time-outs and (b) the time students spent in disciplinary sanctions. Twelve students with emotional/behavioral disorders, enrolled in a self-contained elementary classroom were taught an alternative time-out strategy (Active Response Beads-Time Out), while teachers were taught a re-directing strategy, in an attempt to decrease the amount of student's time spent in time-out (TO) and the number of TO assigned by staff. Using a multiple baseline design across academic classroom periods, results showed that Active Response Beads Time-Out (ARB-TO) and teacher re-directions decreased the total time spent in time-out and number of TO assigned across the three class periods. Results maintained at one, two and four week follow-up sessions.

A novel choice method for studying drugs as punishers

In contrast to reinforcing effects, little is known about the neurobehavioral pharmacology of aversive effects of drugs that may limit their self-administration. The present study was designed to develop a novel choice method for studying drugs as punishers. Rhesus monkeys ( n=4) were trained in a two-lever choice procedure. During a trial, completion of a variable-ratio 10 (VR10) schedule on one lever resulted in the simultaneous injection of a drug and delivery of two food pellets. Completion of an independent VR10 on the other lever resulted in simultaneous delivery of a saline injection and two food pellets. Reinforcer delivery ended a trial and began a time-out (TO) of 10 min. Sessions ended after approximately 4 h. When a preference was observed, injection/lever pairings were reversed to ensure reinforcer preference. When the drug injection was histamine (0.0015–0.006 mg/kg/injection), preference for the drug+food option decreased in a dose-related manner to near 0% in all monkeys. Effective doses of histamine were approximately 10-fold lower than in previously published experiments. In contrast, when the drug was cocaine (0.012–0.2 mg/kg/injection), preference for the drug+food option increased in a dose-related manner to near 100% in all monkeys. Choice may be a sensitive and selective method for studying aversive effects of drugs.

Cocaine-seeking behavior in response to drug-associated stimuli in rats: involvement of D3 and D2 dopamine receptors.

Previous studies employed a second-order schedule paradigm maintained by cocaine reinforcement to show that BP897, a dopamine D(3) partial agonist, selectively modulated drug-seeking behavior. We investigated its effect on drug-seeking behavior induced by presentation of stimuli associated with and predictive of cocaine availability after a period of extinction and in the absence of any further cocaine. Male rats were trained to associate discriminative stimuli (S(D)) with the availability of intravenous (i.v.) 0.25 mg/0.1 ml/infusion cocaine (S(D+)) or no-reward (S(D-)) saline solution. Each infusion of cocaine or saline was followed by a response-cue signaling 20-s time-out (TO). After meeting the self-administration training criterion rats were placed on extinction conditions during which i.v. solutions and S(D)s were withheld. Every other 3 days on which rats met the extinction criterion, reinstatement tests were conducted, presenting the S(D+) or S(D-) noncontingently together with a contingent presentation of cocaine- or saline-cues signaling 20-s TO. Regardless of the order of presentation or the nature of the stimuli (auditory or visual), cocaine-associated but not saline-associated stimuli reinstated responding on the previously active lever. Presentation of cocaine-associated stimuli induced lasting drug-seeking behavior for at least eight test sessions. BP897 (1.0 mg/kg i.p.) significantly attenuated this behavior. Since it has been reported that BP897 can interact with a panel of different receptors with high affinity, we evaluated the effects of 7-OH-DPAT, an agonist to D(3) receptors, raclopride, a preferential antagonist to D(2) receptors, and WAY 100,635, an antagonist at 5-HT(1A) receptors, on drug-seeking behavior. 7-OH-DPAT (0.1-3.0 mg/kg i.p.) had biphasic effects on reinstatement induced by the cocaine-associated cues, low dosages reducing and high dosages increasing the impact of cocaine-associated stimuli on rats' behavior. Raclopride (0.1, 0.3 mg/kg s.c.) completely prevented drug-seeking behavior induced by the reintroduction of cocaine-associated stimuli. WAY 100,635 (0.1-1.0 mg/kg s.c.) had no effect on this behavior. These results, while confirming that the partial agonist at the D(3) receptors, BP897, might be a useful medication, also suggest a role of D(2) receptors in cue-induced cocaine-seeking behavior.

Analysis of synchronization algorithms with time-out control over networks with exponentially symmetric delays

We study the performance of a class of time-offset estimation algorithms for synchronization of master-slave nodes based on asynchronous transfer of timing cells when GPS is not used. We implement a synchronization control mechanism based on cell acknowledgment time-out (TO) with wait or no wait options. We analyze the mechanism reliability and performance parameters over symmetric links using an exponential cell delay variation model. We show that the maximum-likelihood offset estimator does not exist for the exponential likelihood function. We analytically provide RMS error result comparisons for five ad hoc offset estimation algorithms: the median round delay, the minimum round delay, the minimum link delay (MnLD), the median phase, and the average phase. We show that the MnLD algorithm achieves the best accuracy over symmetric links without having to impose a strict TO control, which substantially speeds up the algorithm. We also discuss an open-loop estimation updating mechanism based on standard clock models.

Effects of negative punishment contingencies on cocaine self-administration by rhesus monkeys.

Although punishment contingencies are widely used with human drug users, basic research on the effectiveness of these procedures is limited. The present study evaluated the effects of a negative punishment contingency, response-contingent timeout (TO) presentation, on cocaine-maintained responding. Rhesus monkeys were trained under a multiple fixed-interval (FI) 5-min cocaine, conjoint FI 5-min cocaine, variable-interval (VI) 30-sec TO schedule. TO values were either 0 (baseline), 10, 30, or 60s in length. During the TO periods, the FI clock continued to operate but the discriminative stimuli signaling cocaine availability were removed, and responding had no scheduled consequence. Cocaine maintained responding in all monkeys and the dose-effect curve was characterized as an inverted U-shaped function. The response-contingent TO presentations reduced response rates maintained by cocaine in all monkeys compared to baseline. The magnitude of the reduction in response rates was not a function of the length of the TO period (i.e. intensity of the punisher), and the punishment effect was enhanced by increases in cocaine dose. When responding was punished, response rates in the unpunished components either also decreased (i.e. response induction; approximately 30% of the cases) or were not affected (approximately 60%). These results demonstrate that cocaine-maintained behavior can be decreased by environmental manipulations involving negative punishment contingencies.

Changes in linguistic variables during operant, laboratory control of stuttering in children

Response contingent stimulation (RCS) is known to reduce stuttering in many cases. Time-out (TO) from speaking after stuttering is a particularly effective form of RCS. However, the mechanism underlying the TO effect is unknown. The demonstrated value of operant methods in the clinical control of stuttering in young children warrants renewed interest in exploring why pausing for a short time after stuttering would reduce the frequency of stuttering. In this study, selected linguistic measures were made for two school-age boys whose stuttering reduced during TO in a laboratory study. One boy showed a clear reduction in verbal output, accompanied by a reduction in lexical diversity, but the other boy showed no changes in linguistic measures. This finding is of interest because, in a previous acoustic analysis of the same speech samples, the first boy showed no changes in acoustic speech measures of duration while the second boy did show changes in acoustic speech measures of duration. This raises the possibility that people who stutter may change their verbal output in response to TO, but in different ways. Although the present data do not establish a causal relationship between alterations in verbal output and reductions in stuttering, they raise the need for further research that might explain why TO might control stuttering.

Cocaine-seeking by rats: regulation, reinforcement and activation

In animal models of drug self-administration, response rates often decrease with dose suggesting that a regulative process may mask the reinforcing effects of the drug. The purpose of the present experiments was to dissociate the role of regulative and reinforcement processes in intravenous cocaine self-administration by rats using a paradigm that explicitly distinguishes between drug-seeking and drug-taking. Rats were trained to respond for intravenous cocaine (0.25 mg/infusion) under a heterogeneous chain (tandem FR1 RI 30 s) FR1 schedule of reinforcement using different levers in the first (seeking) and second (taking) links of the chain. After 10 days of training, rats were switched to one of three doses of cocaine (0.08, 0.25, or 0.5 mg/infusion) and self-administration patterns were recorded for a further ten sessions in experiment 1. In experiment 2, a time-out (TO) period (0, 4, or 12 min) was imposed between successive cycles of the chain schedule. Finally, the effect of allowing animals to perform a drug-taking response on subsequent drug-seeking was assessed in experiment 3. Having verified that seeking responses for a conventional reinforcer (sucrose) were sensitive to changes in reward magnitude, experiment 1 demonstrated that the number of self-administered infusions was inversely related to dose whereas the latency to initiate drug-seeking increased with dose. Variations in the cocaine dose had no reliable effect on the number of drug seeking response per cycle of the chain schedule. The effect of dose on the latency to initiate drug-seeking was reversed in experiment 2 with increasing TO periods. Moreover, at the longest TO period, drug-seeking responses per cycle increased and the latency to initiate drug seeking decreased with dose. Experiment 3 showed that the latency to drug-seek for the low dose was reduced dramatically when the first drug-seeking response was preceded by a drug-taking response, even when this response did not produce a drug infusion. The overall pattern of results suggests that drug-seeking and drug-taking are controlled by three interacting processes: a regulative process depresses drug-seeking in the short-term; behavioral activation enhances drug-seeking and is sustained over longer intervals by higher drug doses; the reinforcing effect of cocaine increases with dose once the satiety producing effects of the drug dissipate.

Site-specific NMDA receptor antagonists produce differential effects on cocaine self-administration in rats

The effects of site-specific NMDA receptor antagonists on intravenous cocaine self-administration were examined in rats trained to self-administer cocaine (0.25 mg/infusion) on a fixed ratio (FR) 5 schedule with a 20-s time-out (TO) after each reinforcer. The non-competitive NMDA receptor antagonists, dizocilpine (MK-801, (+)-5-methyl-10,11-dihydro-5 H-dibenzo[ a,d]cyclohepten-5,10-imine hydrogen maleate) (0.05–0.2 mg/kg i.p.) and memantine (1,3-dimethyl-5-amino-adamantane hydrochloride) (2.5–20 mg/kg i.p.), dose-dependently decreased cocaine self-administration, while the competitive NMDA receptor antagonist, CGP 39551 ( dl-( E)-2-amino-4-methyl-5-phosphono-3-pentanoic acid carboxyethylester) (2.5–15 mg/kg i.p.), and the NMDA/glycine receptor antagonist, L-701,324 (7-chloro-4-hydroxy-3(3-phenoxy)-phenyl-2( H)quinolone) (1.25–10 mg/kg p.o.), were without effect. Under a progressive ratio (PR) schedule, dizocilpine (0.15 mg/kg i.p.) increased the number of cocaine infusions in a manner similar to increasing the unit dose of cocaine, suggestive of potentiation of cocaine reward. Conversely, memantine (10 mg/kg i.p.) produced rate-decreasing effects on the PR schedule. These results demonstrate that NMDA receptor antagonists acting at different modulatory sites of the NMDA receptor do not share dizocilpine's cocaine reward enhancing effects although they are all known to be effective blockers of NMDA receptor activity.

Effects of the group II metabotropic glutamate receptor agonist, LY354740 on schedule-controlled behaviour in rats.

The present study examined the effect of the novel, systemically active Group II metabotropic glutamate (mGlu) receptor agonist, LY354740, on schedule-controlled behaviour in rats. Responding for food reward was maintained by three different operant procedures; the first, a three-component conflict schedule; the second, a multiple fixed-interval 60 s/fixed-ratio 10 (FI60/FR10) schedule and the third, a differential reinforcement of low rates of responding 10 s (DRL10) schedule. In the first procedure, rats were trained to respond for food on a schedule comprising of variable-interval 30 s (food, VI30) and fixed-ratio 10 (food + shock, FR10) components separated by time-out (TO). LY354740 (1.25-5 mg/kg, i.p.) produced a dose-related reduction in responding during the VI component and increased responding during the TO component, while having no effect on responding during the punished FR10 phase. In the FI60/FR10 schedule, LY354740 produced a dose-related reduction in the high rates of responding observed during the FR10 component of the schedule. Although LY354740 (0.6-10 mg/kg, i.p.) had no effect on the overall response rates produced by the FI60 component, there was a shift in the temporal distribution of responding as measured by the quarter-life. LY354740 (10 mg/kg, i.p.) increased the low rates towards the start of the interval, while decreasing the rates of responding towards the end of the FI60 period. In the DRL10 s schedule, LY354740 (5-20 mg/kg, i.p.) had no effect on the total number of responses but produced a significant reduction in the total number of rewards, suggesting that the temporal control of responding had been disrupted. The changes in operant responding occurred at doses that decreased exploratory behaviour. In summary, LY354740 modified responding maintained by all three operant schedules at doses which suppressed spontaneous activity. These data demonstrate that stimulation of Group II mGlu receptors can produce changes in responding which are dependent on the base-line rate of responding, suggesting that mGlu 2/3 receptors may be involved in the stimulus and temporal control of behaviour.

Study on the Sternberg paradigm in cirrhotic patients without overt hepatic encephalopathy.

Memory dysfunction is reported in cirrhotics. The aim of this paper was to increase insight into memory function of cirrhotic patients without overt hepatic encephalopathy. Eighty-six consecutive cirrhotics without overt hepatic encephalopathy (aged 54+/-10 yr., mean+/-s.d.) and 28 controls (52+/-10 yr.) with comparable education level were enrolled. Seventeen patients were class A, 55 class B, 14 class C according to Child-Pugh classification; 29 had alcoholic cirrhosis. The presence of subclinical signs of central nervous system dysfunction were assessed by Number Connection Test (NCT) and quantified EEG analysis. Memory scanning was evaluated by reaction times (RTs) in the Sternberg paradigm. MANOVA analysis showed that RTs were higher (F1,99=11, p<0.01) and time outs (TOs) more frequent (F1,110=10, p<0.01) in cirrhotics than in controls, whereas button press errors (BPEs) did not differ significantly (F1,110=2, p=n.s.). In cirrhotics, an interaction Child-Pugh class x memory set size was found (F2,146=4, p<0.05), showing exceedingly delayed RTs with greater memory set size in class C patients. Patients with altered NCT had significantly prolonged RTs (F1,71=4, p<0.05) and more TOs (F1,82=11, p<0.01) than patients with normal NCT. Cirrhotics with altered EEG had significantly prolonged RTs (F2,70=6, p<0.01). RTs were found to be correlated to alpha relative power (r=-0.4, p<0.01) and theta relative power (r=0.4, p<0.01). In conclusion, cirrhotics without over encephalopathy, but with NCT or EEG alterations, perform a computerized digit recognition task more slowly and with higher TOs than cirrhotic patients with normal NCT or EEG. In severe liver insufficiency (class C cirrhotics) also an impairment of memory scanning was detected. Sternberg test performance correlates with NCT and quantitative EEG parameters.

Deregistration strategies for PCS networks

This paper studies three deregistration strategies (explicit, implicit, and timeout (TO) deregistration) for personal communication service (PCS) networks to determine the network conditions under which each strategy, gives the best performance. Two performance measures are considered: (1) the probability /spl alpha/ that a portable cannot register (and receive service) and (2) the number of deregistration messages sent in a strategy. For the same database size, /spl alpha/ is smaller for explicit deregistration (ED) than it is for TO or implicit deregistration (ID). On the other hand, ID does not create any deregistration message traffic. With an appropriate TO period, the deregistration message traffic for TO deregistration is much smaller than the traffic for ED. Suppose that there are N portables in a registration area (RA) on the average. To ensure that /spl alpha/<10/sup -3/ our study indicates that if the database size is larger than 4N, then the implicit scheme should be selected (to eliminate deregistration traffic). If the database size is smaller than 1.5 N, then the explicit scheme should be selected. Otherwise, the TO scheme should be selected to achieve the best performance.

Control of Children's Stuttering With Response-Contingent Time-Out

Many stuttering treatments incorporate contingencies for stuttering that are thought to contribute to treatment effectiveness. One contingency used in a number of treatment programs for children is time-out (TO) from speaking. However, although TO has been shown to control stuttering in adults there are no clear demonstrations of this effect in children. One aim of the present study was to demonstrate in the laboratory that TO reduces stuttering in children. Three school-age children spoke in a single-subject ABA experiment. In the B phase, a red light was illuminated for 5 seconds when the subject stuttered, during which time the subject stopped talking. Two of the three children showed clear reductions in stuttering in response to TO. The second aim of the study was to detect whether the children who responded to To adopted an unusual speech pattern in order to control their stuttering. Listeners did not detect any differences between the perceptually stutter-free speech of baseline conditions and that of TO conditions, and a subsequent acoustic analysis revealed a reduction in the variability of vowel duration during TO in one subject and no changes in the other. The theoretical and clinical implications of the findings are discussed.

Effects of olanzapine and other antipsychotic agents on responding maintained by a conflict schedule.

The effects of the "atypical" antipsychotic olanzapine and several other antipsychotics were examined using a conflict schedule. Rats were trained to respond for food on a three-component schedule, comprising variable-interval 30s (food, VI30) and fixed-ratio 10s (food + shock, FR10) components separated by time-out (TO). Olanzapine (0.3125-1.25mg/kg), clozapine (1.25-5mg/kg) and chlordiazepoxide (2.5-5mg/kg) decreased or had no effect on VI30 responding, whereas responding in the FR10 component increased. Chlordiazepoxide (5mg/kg) also increased TO responding. The antipsychotic agents haloperidol (0.125 and 0.25mg/kg), trifluoperazine (0.0625-0.25mg/kg), remoxipride (1.25-5mg/kg) and risperidone (0.0625-0.5mg/kg) decreased V130 responding and either had no effect, or decreased TO and FR10 rates. The anticholinergic agent scopolamine (0.03125-0.25mg/kg) decreased VI30 responding. The 5-HT(2) antagonist ritanserin (2.5 and 5mg/kg) and the anticholinergic agent trihexyphenidyl (2.5 and 5mg/kg) had no effect on responding. Flumezanil (10mg/kg) reduced the anticonflict effect of chlordiazepoxide but not olanzapine. These results further emphasize the unusual profile of olanzapine.

Limitations of “don't” instructional control

This study examined the relative efficacy of a prohibitive (“don't”) instructional procedure compared with immediate timeout (TO) in reducing physical aggression between siblings. The “don't” instructional procedure included “don't” instructions, praise for compliance (i.e., inhibiting on-going aggression), warnings for noncompliance (i.e., continued fighting), and chair TOs for noncompliance to warnings. An alternating treatment design was employed with three oppositional, aggressive, preschool children and their mothers in the home setting. Sibling aggression data were collected by the mother. The reliability of maternal observations, however, was not independently confirmed. Results suggested that the immediate TO procedure was more effective than the “don't” instructional procedure. Sibling aggression appears to be a misbehavior that is not readily treated with an obedience-provoking routine. Theoretical reasons behind the limitations of “don't” instructional control are discussed.

Effect of eseroline on schedule-controlled behavior in the rat

Male Sprague-Dawley rats were trained to press a lever on a simple-alternation multiple fixed-ratio (FR) 20-response time-out (TO) schedule for water reinforcement. Twelve 5-min periods of FR reinforcement were each followed by a 5-min TO in which responding had no scheduled consequence. Doses ranging from 0.25 to 8 mg/kg of eseroline, the hydrolysis product of eserine and a potent analgesic agent with weak anticholinesterase activity, were administered SC immediately prior to a 120-min test session. Eseroline produced a dose-dependent monotonic decrease in the number of reinforcements, with significant effects at doses of 1, 2, 4 and 8 mg/kg and an ED 50 of 2.5 (1.6–3.4) mg/kg. This behavioral disruption was characterized by a rapid onset of pausing (i.e., within 5 min postdosing) and a gradual recovery to normal baseline levels of responding over the remaining session time. The duration of the rate decreasing effects was dose-related with the highest dose having a mean duration of more than 60 min, which was longer than that of previous reports on antinociception produced by eseroline (<60 min). The coadministration of behaviorally inactive doses of the opiate antagonist naloxone (1 and 2 mg/kg, IP) with eseroline (2.5 mg/kg, ED 50) antagonized the effects of eseroline on the operant behavior. The coadministration of behaviorally inactive doses of the muscarinic antagonist atropine with eseroline (2.5 mg/kg) did not affect eseroline's behavioral effect. These results suggest that the effects of eseroline on operant behavior is consistent with the effects of eseroline-induced antinociception, reported previously, and appears to be associated with the activation of opiate receptors, but not related to the stimulation of muscarinic receptors via its anticholinesterase activity.

Adjusting chair timeout enforcement procedures for oppositional children

Mothers of noncompliant, clinic-referred preschool children were randomly assigned to 1 of 4 chair timeout (TO) enforcement procedures: Spank, Hold, Barrier, or Child Release. Standardized Forehand compliance training was implemented. Hold procedures were associated with less compliance criterion performance and excessive TO escape efforts. Child Release procedures were associated with excessive TOs. Neither Hold nor Child Release procedures are recommended. Barrier and Spank procedures appeared equally effective, replicating prior studies. The importance of monitoring and adjusting initial clinic TO enforcement procedures was documented. Noncompliant children who resisted TO displayed significantly less improvement in compliance than noncompliant children who accepted TO. Group data were obtained in the home setting across a four-week period. Most children displayed near-zero levels of TO resistance within 3 weeks in the home.

Opioid receptor subtype-specific cross-tolerance to the effects of morphine on schedule-controlled behavior in mice.

Key-press responding of mice was maintained under a fixed-ratio (FR) 30-response schedule of food presentation. Successive 3-min periods during which the experimental chamber was illuminated and the schedule was in effect were preceded by 10-min time-out (TO) periods during which all lights were out and responses had no scheduled consequences. Intraperitoneal (IP) injections of saline or of cumulative doses of drugs were given at the start of each TO period. Successive saline injections had little or no effect on response rates, whereas the mu-opioid agonists morphine (0.1-10.0 mg/kg) and levorphanol (0.1-3.0 mg/kg), the kappa-opioid agonist ethylketazocine (0.03-3.0 mg/kg), the mixed mu-/delta-opioid agonist metkephamid (0.1-10.0 mg/kg), and the nonopioid dissociative anesthetic ketamine (1.0-100.0 mg/kg) generally produced dose-related decreases in response rates. Following chronic administration of morphine (100.0 mg/kg/6 h), tolerance developed to the effects of morphine on rates of responding. In addition, a comparable degree of cross-tolerance developed to the effects of levorphanol and metkephamid. On the other hand, there was no evidence of cross-tolerance to the effects of ethylketazocine or ketamine. These results are consistent with the evidence suggesting that different opioid agonists exert their behavioral effects through distinct classes of opioid receptors.

Alternative treatments for sibling aggression

Eighteen clinic-referred, aggressive pairs of siblings and their mothers participated in one of three brief clinical interventions. Participant observation of aggressive episodes in the home setting served as the treatment outcome measurement. All sibling pairs participated in four clinic treatment sessions consisting of one of three treatments: Social Skills (SS), Timeout (TO), or Combination (COMBO). Training procedures consisted of observation of videotaped child models reacting to typical conflict situations, verbal rehearsals, role-playing, and parent training. Between treatment sessions, all mothers recorded aggressive episodes in the home and consequated such behavior with either discussion, timeout, or a combination of these events. The data indicated that timeout training was more effective than social skill training. Social skill training may also have been useful, however, especially for children from higher socioeconomic status homes. It was concluded that initial treatments for sibling aggression should include a discipline component.

Effects of ketocyclazocine alone and in combination with naloxone on schedule-controlled responding in squirrel monkeys

A multiple, fixed interval 5 minutes, fixed ratio 30, schedule of food presentation (Mult FI FR) was used to evaluate the effects of ketocyclazocine, a kappa-receptor agonist, in four squirrel monkeys. Two monkeys were initially trained with 1-minute time-out (TO) periods between the components of the multiple schedule and two monkeys were initially trained without these TO periods. Ketocyclazocine dose-response functions were determined for each monkey under their original training conditions and then the conditions were reversed and dose-response functions were re-determined under the new conditions. Ketocyclazocine consistently decreased rates of responding during the FR component of the multiple schedule under both TO and no TO conditions. Under the FI component, ketocyclazocine's effects differed dependent upon dose, conditioning history, and the presence or absence of TO periods. Intermediate doses of ketocyclazocine (0.01-0.056 mg/kg) increased FI rates of responding under the no TO condition in monkeys originally trained under this condition; however, ketocyclazocine did not increase FI rates of responding under the no TO condition in monkeys originally trained under the TO condition. Under the TO condition, intermediate doses of ketocyclazocine did not increase FI rates of responding. High doses of ketocyclazocine (0.1 and 0.17 mg/kg) decreased FI rates of responding in all monkeys under both the TO and no TO conditions Naloxone, in doses up to those which decreased responding when given alone, failed to antagonize completely the rate decreasing effects of ketocyclazocine.

Stimulus Control of the Pigeon’s Ability to Peck a Moving Target II: Compound Stimuli and Intermittent Reinforcement

In Experiment 1, three pigeons were trained to peck whichever of eight keys displayed a white “x” on a red background (SD). The other seven keys displayed a white circle on a green background (SΔ). Each peck to SΔ produced a 3-sec access to grain, a 3-sec intertriai interval (ITI), and the next trial. Pecks to SA produced a 5-sec timeout (TO) and the same trial. During later sessions, the key displaying SD changed every t seconds (t = 3, 2, 1,.5,.25, and.025 sec), requiring the birds to track the position of the SD. Pecks on a ninth key increased t. In Experiment 2, the color and form elements of SD were presented separately and moved every t seconds towards merging on one key. The birds had to regulate the speed of movement then peck only keys with the compound SD present in order to produce reinforcers. Experiment 3 allowed the birds to eliminate S A stimuli by pecking the ninth key during each trial. Experiment 4 employed novel stimuli, to ascertain the controlling stimulus dimensions. The birds made few errors acquiring the original discrimination. Each bird reliably lengthened and shortened t, waited for the red and “x” to merge on one key, and eliminated SΔ stimuli. Data from sessions with novel stimuli indicate that color, form, and movement contributed to the final performance.