Schedule Components Research Articles

Antagonism by methysergide of the effects of l-5-hydroxytryptophan and quipazine on schedule-controlled responding

Dose-effect curves for l-5-hydroxytryptophan and quipazine were determined alone and in the presence of small doses (0.3 and 1 mg/kg) of methysergide in pigeons responding under a multiple fixed-ratio 30-response, fixed-interval 5-min schedule of grain presentation. Both serotonergic agonists produced dose-related decreases in responding in both schedule components. Methysergide produced a 2- to 3-fold shift of the dose-effect curve to the right (antagonism) for both serotonergic agonists. It was concluded that l-5-hydroxytryptophan and quipazine decrease rates of responding by an action at a methysergide-sensitive serotonergic receptor.

A system for using supplemental staff.

This article has outlined the development of a system for using temporary nurses. Steps in this process include reevaluation of department philosophy; formulation of criteria for temporary staffing; development of scheduling mechanisms and policies that reflect the criteria; and finally, the development of methods for evaluation. Our system uses scheduling components previously in existence at Rush-Presbyterian-St. Luke's Medical Center. We consider the computerized system an advantage for our purposes, but it was not essential. A written schedule could then be used to meet department needs. Defining goals and then determining methods is important, since several alternative methods might be possible to meet a goal. Our system emphasizes both continuity and accountability at the unit level. Because the unit leaders have close association with temporary staff, their input is vital. The unit leaders formally evaluate the temporary personnel and are accountable for making appropriate requests for temporary staff. The judgment of need is based on such factors as patient needs, budget allocation, and staff vacations. The system outlined was the necessary by-product of the interfacing of two staffing methods, permanent and temporary. Consistency is the key to resolving problems.

The Effects of D-Amphetamine and Chlordiazepoxide on Responding Maintained by a Multiple Schedule of Food and Electrical Brain Stimulation in Rats

Rats were exposed to a multiple variable-interval schedule of food or electrical stimulation of the lateral hypothalamus. When stable behavioral baselines had developed, the effects of several doses of chlordiazepoxide (2.5, 5, 10, and 20 mg/kg) and of d-amphetamine (.25, .5, and 1 mg/kg) were assessed. Chlordiazepoxide was found to have similar effects on responding maintained by both reinforcers, low doses increasing response rates and the highest dose reducing them. This drug also increased the duration of brain stimulation, which was under the control of the rats. The effects of d-amphetamine, in contrast, were different in the two schedule components. Responding maintained by brain stimulation was substantially increased by d-amphetamine which, however, produced either only small increases or even decreases in response rates maintained by food. The different effects of d-amphetamine in the two schedule components could not be explained in terms of differences in baseline response rates. It is therefore concluded that in some circumstances the actions of d-amphetamine are dependent on the reinforcing event maintaining behavior.

Second-Order Schedule Effects With Goldfish: A Comparison of Brief-Stimulus, Chained, and Tandem Schedules

The performance of goldfish was examined under two-component chained and tandem food reinforcement schedules with and without brief stimuli added. Both food-paired and nonpaired brief stimuli were evaluated under conditions in which each component schedule was a fixed-interval 90- sec and the operant response was contact with the feeder tube. In general, the chained schedule engendered a higher rate of responding than the tandem schedule. Responding within a schedule occurred at the highest rate when a food-paired brief stimulus (tone) was used. The brief stimulus not paired with food had little effect on responding. Under both the tandem and chained schedules, a pronounced pattern of positively accelerated responding was observed within the initial component when the food-paired brief stimulus was presented. These results indicate that in goldfish, as in better studied species, a briefly presented food-paired stimulus is a more effective conditioned reinforcer than the presentation of a discriminative stimulus associated with a schedule component under which food is earned, which is in turn more effective than a nonpaired brief stimulus.

Effects of tetrabenazine and phenylpiperidine analgesics during daily clorgyline treatment

Pigeons responded under a multiple fixed-ratio 30-response, fixed-interval 5-min schedule of food presentation. Daily administration of clorgyline (10 mg/kg, IM) tended to decrease rates of responding in both schedule components. Before daily clorgyline, tetrabenazine had no effect or decreased responding in the FI component at doses that markedly increased responding during chronic clorgyline. The clorgyline treatment resulted in a slight increase in sensitivity to the rate-decreasing effects of morphine, but no increased sensitivity to the rate-decreasing effects of meperidine, anileridine, alphaprodine, or fentanyl.

Rats Show a Component Preference on a Multiple Variable Interval Variable Time Schedule for Food

Rats obtained food pellets by lever pressing on a variable interval (VI) schedule or obtained them freely on a variable time (VT) schedule. Alternation of schedule components occurred when the rat emitted a changeover response on one of the two response levers in the chamber. In Experiment 1, the work (VI) lever retracted on entry into the VT component. Rats which had access to the changeover lever from the beginning of VI training showed a strong preference for free food (VT component). Rats which received 13 days of VI training prior to access to changeover lever showed a slight preference for work (VI component). If the work lever did not retract (Experiment 2) on entry into the VT component, the results were essentially the same.

DIFFERENTIAL RESPONDING WITHOUT DIFFERENTIAL REINFORCEMENT: INTENSITY DIFFERENCE, CONTINUUM POSITION, AND REINFORCEMENT DENSITY EFFECTS

The response rates of five groups of rats were observed during exposure to different intensities of a four kilohertz tone within a two-component multiple schedule of nondifferential reinforcement. Response rates were found to be higher during the multiple schedule component which contained the higher intensity tone. Larger differences in response rates between the two multiple schedule components occurred with greater intensity separations (30 versus 20 decibels). At the 30 decibel separation a low absolute magnitude produced larger response rate differences than a high absolute magnitude, while at the 20 decibel separation a high absolute magnitude produced larger response rate differences. Increases in reinforcement density were accompanied by decreases in response rate differences between high and low intensity components only when over-all response rates also increased.

REINFORCEMENT OF HUMAN OBSERVING BEHAVIOR BY A STIMULUS CORRELATED WITH EXTINCTION OR INCREASED EFFORT

Young men pulled a plunger on mixed and multiple schedules in which periods of variable-interval monetary reinforcement alternated irregularly with periods of extinction (Experiment 1), or in which reinforcement was contingent on different degrees of effort in the two alternating components (Experiment 2). In the baseline conditions, the pair of stimuli correlated with the schedule components could be obtained intermittently by pressing either of two observing keys. In the main conditions, pressing one of the keys continued to produce both discriminative stimuli as appropriate. Pressing the other key produced only the stimulus correlated with variable-interval reinforcement or reduced effort; presses on this key were ineffective during periods of extinction or increased effort. In both experiments, key presses producing both stimuli occurred at higher rates than key presses producing only one, demonstrating enhancement of observing behavior by a stimulus correlated with the less favorable of two contingencies. A control experiment showed that stimulus change alone was not an important factor in the maintenance of the behavior. These findings suggest that negative as well as positive stimuli may play a role in the conditioned reinforcement of human behavior.

Fixed ratio schedules of food presentation and stimulus shock termination: effects of d-amphetamine, morphine, and clozapine.

Squirrel monkeys responded under a multiple schedule in which 30 responses during a specified time limit resulted in either food presentation or termination of visual stimuli associated with impending shoch delivery. Schedule components were associated with different colored lights and were separated by 60-s time-out periods in which all lights were extinguished. If the response requirement was not met within the time limit, either the time-out period alone (food components) was presented or a single shock was delivered coincident with onset of time-out. In experiments with d-amphetamine, different control rates of responding were engendered by varying the time limit. When the time limit was 60s, all monkeys responded at higher overall rates during food presentation components. When the time limit was reduced to 15 s, rates of responding in both components increased and became more similar than under the 60-s limit. When control rates in the two components differed under the 60-s time limit, d-amphetamine sulfate (0.01-1.0mg/kg) increased the normally lower rates under the shock schedule at intermediate doses, but generally only decreased the higher rates under the food schedule. With more comparable control rates under the 15-s time limit, the effects of amphetamine were also more comparable. In most cases low and moderate doses either had little effect or slightly increased responding in both schedule components and higher doses decreased responding. Morphine sulfate (0.03-1.7mg/kg) and clozapine (0.1-3.0mg/kg) decreased responding comparably under both food and shoch schedules with the 15-s time limit.

Factors affecting the conditioned reinforcing strength of stimuli in differential reinforcement of other behavior and fixed-time schedules

In an experiment that investigated the effects of a low-rate response requirement on the strength of conditioned reinforcing stimuli, pigeons’ observing responses (treadle presses) produced stimuli associated with either a short (10-sec) or a long (30-sec) schedule component. Naive pigeons were exposed to a mixed schedule with two differential reinforcement of other behavior (DRO) components, which were later replaced by fixed-time (FT) components. Differ- ential observing behavior was not maintained during the DRO procedure, but preference was demonstrated for the shortest FT component stimulus. Fantino’s delay-reduction hypothesis was supported. However, the absence of differential observing under the DRO procedure suggests that either the low-rate response requirement or the lack of specific stimuli that unambiguously predict reinforcement delivery interfered with the establishment of the schedule stimuli as conditioned reinforcers.

Facilitatory effect of ketamine on punished behavior

In order to compare the effect of ketamine on punished and unpunished operant responding with that of pentobarbital and amphetamine, pigeons were trained to perform under a multiple fixed-interval 5 min, fixed-interval 5 min (shock) schedule of food presentation. In both schedule components, the first response after 5 min produced access to grain (F15). In the punished component every response was followed by electric shock delivery. Lower effective doses of ketamine (1.7–5.6 mg/kg) caused moderate increases in punished FI responding with little or no alteration of unpunished response rates. Higher doses (10 and 17 mg/kg) decreased both punished and unpunished FI rates. Large increases in punished responding were caused by 10 mg/kg of pentobarbital. This and lower doses of the latter drug also moderately increased non-punished FI responding. The highest dose of pentobarbital used (17 mg/kg) decreased unpunished FI response rates while still increasing punished FI rates. Amphetamine caused dose-dependent decreases in punished responding at doses (0.17–1.0 mg/kg) that did not affect unpunished responding. Higher doses (1.7 and 3.0 mg/kg) of amphetamine also decreased unpunished FI rates, but to a lesser extent than punished response rates. From these and other reported results it may be concluded that ketamine affects schedule controlled behavior in characteristic ways, different from both minor tranquilizers and amphetamine-like drugs.

Behavioral and dimensional contrast in rats.

Rats pressed a nose key for brain stimulation reinforcement presented on a fixed-interval schedule. Stimuli were drawn at random from a continuum of 12 white noise intensities in the range 62-95 decibels, spaced in 3 decibel steps. Experiment 1 varied the number of stimuli and the reinforcement contingencies associated with them. In Condition I (baseline) all stimuli signaled reinforcement; in Conditions II and III stimuli from one half of the continuum signaled reinforcement and those from the other half, extinction. However, in Condition II the 6 stimuli from the middle of the continuum were omitted. Experiment 2 held constant the number of stimuli and varied their spacing. In Condition I, each of 6 sounds signaled reinforcement. In Conditions II and II, three stimuli from one half of the continuum signaled reinforcement and three from the other half, extinction. However, in Condition II the stimuli were near the extremes of the continuum (Stimuli 1, 3, 4, 9, 10, 12). Condition III replaced Stimulus 3 with Stimulus 6 and Stimulus 10 with Stimulus 7. Behavioral contrast was seen in an increase over baseline in response rate to the stimuli associated with the constant schedule component when the variable component was changed to extinction. Dimensional contrast was seen in a further elevation of rate to intermediate positive stimulus values when stimuli were added to the border region between positive and negative values.

SHORT‐TERM MEMORY IN THE RHESUS MONKEY: A BEHAVIORAL ANALYSIS OF DELAYED‐RESPONSE PERFORMANCE

This study obtained quantitative data on the bodily orientations of rhesus monkeys in a delayed-response task and determined whether such orientations mediate the correct response in a choice trial. The basic task was a two-key chain schedule with the key leading to food signaled in the initial component. During the subsequent delay interval, the signal was removed, but it was necessary that one of the keys be pressed to advance the schedule to the terminal choice component. The position of the key pressed thus indicated orientation during the delay interval. When the monkeys had free access to the left and right keys, they tended to press the key leading to food throughout the chain schedule components and received food on more than 85% of the trials, even when the delay was extended to 20 seconds. However, when orientation toward the food key was disrupted by forcing the monkeys to press an extraneous center key during the delay, choice performance deteriorated. Requiring the center key presses early, rather than late, in the delay component had a strong disruptive effect. The relation of the results to the mediating coding-response hypothesis is discussed.

Rats show no preference between free and earned water in an advance-response procedure

Although an arbitrarily specified instrumental response may persist when free reinforcers are concurrently available, the interpretation that earned reinforcers are preferred is tenuous. The present advance-response procedure used both time allocation and advance response rates as indices of preference between free and earned water in rats. When multiple schedule components were two response-dependent schedules with different overall reinforcement rates, higher rates of reinforcement were preferred. However, when the multiple schedule consisted of response-dependent and response-independent components equated for overall rates of reinforcement, no consistent preference for free or earned reinforcers was evident. That a preference for free reinforcers was not obtained is difficult to reconcile with concepts of least effort.

Effects of acute and chronic administration of phenobarbital and d-amphetamine on schedule-controlled behavior

The effects of acute and chronic administration of phenobarbital and d-amphetamine were determined in rats responding under a multiple fixed-interval five minute fixed-ratio 30 (mult FI 5 FR 30) schedule of food presentation. After determining the acute effects of each drug, the drugs were injected daily with one group of rats receiving the drugs before each behavioral session while another group received the drugs immediately after each daily session. After four to seven consecutive injections, tolerance developed to the effects of phenobarbital on the average rates of responding under FI and FR schedule components only if the drug was administered before each session. Tolerance was more pronounced for responding during the terminal portions of the FI component than for responding during either the initial portions of the FI or the FR component. Evidence for a selective tolerance to the effects of the drug on responding during the final segments of the FI was also obtained in rats responding under an FI 5 schedule. In contrast, injections of d-amphetamine for seven to eight consecutive days failed to produce any tolerance to the effects of the drug on responding under mult FI 5 FR 30, FI 5, or FR 30 schedules. These results indicate that the development of tolerance to the effects of phenobarbital depended both upon the temporal relationship of the drug effects to the behavioral testing and upon the schedules controlling behavior. These findings are discussed in terms of theories of behavioral tolerance.

Behavioral influences on tolerance to the effects of morphine on schedule-controlled behavior.

Responding of pigeons was maintained under a multiple fixed interval, fixed ratio schedule of food delivery, and 10 mg/kg morphine was administered daily. Responding during both schedule components was initially decreased and measurable tolerance developed to this effect after four daily injections. However, the rate of tolerance development differed depending on whether or not presence of the drug coincided with performance during experimental sessions. Tolerance developed more rapidly when morphine was given before daily experimental sessions than when morphine was given daily but animals did not perform daily in experimental sessions. Tolerance to the rate-decreasing effects of morphine depended on relations between presence of the drug and exposure to experimental sessions.

Positive Contrast in the Rat: A Test of the Additivity Theory

Rats were trained to lever press for food on a multiple variable-interval variable-interval schedule, then shifted to a multiple variable-interval extinction schedule. For six subjects (group L), schedule components were signalled by the presence or absence of a flashing light emitted from an alternate, "signal" lever. For four subjects (group T), schedule components were signalled by two distinct auditory tones. Contrary to the predictions of an additivity theory based on the summation of response classes, contacts on the signal lever did not increase after the schedule shift in group L. However, nine of the ten subjects in the study demonstrated positive contrast effects on the operant lever. In a subsequent test for stimulus control, enhancement and suppression by the discriminative stimuli were found in these same nine subjects. An additivity theory based on the summation of excitatory processes, rather than response classes, appears to account for these data.

Effects of response-contingent clock stimuli on behavior maintained by intravenous codeine in the rhesus monkey

Response-contingent brief presentations of clock stimuli differentially correlated with food availability altered rates of codeine-maintained lever pressing. Rhesus monkeys performed under a two lever multiple schedule: Multiple fixed interval clock 5 min variable interval 2 min. Different colored lights were presented during successive 75 sec periods of the fixed-interval clock component. Lever pressing under the FI Clock schedule was maintained by presentation of 1 g Noyes pellets, and lever pressing under the VI schedule by 0.05 mg/kg infusions of codeine PO 4. Characteristic schedule-controlled performance developed in both schedule components. When the clock stimulus from the first or the final period of the FI Clock schedule was presented contigent upon completion of a short fixed ratio of responses during the variable-interval schedule component, the first clock stimulus decreased and the final clock stimulus increased rates of codeine-maintained lever pressing. Neither the first nor the final clock stimulus altered the frequency of codeine injection. The effect of each clock stimulus was accentuated by increasing the duration of stimulus presentation and by decreasing the response requirement for stimulus illumination. These rate-altering effects of the clock stimuli were most pronounced when different reinforcers were presented in the two components of the multiple schedule when either food or intravenous codeine injection was available under both components of the multiple schedule, response-contingent clock stimulus presentation did not alter response rates under the VI schedule.

Improvement of Supervision Schedules for Protective Systems

Improvement of supervision schedule is considered for protective-systems of multiple components. Each component is periodically supervised. Our improvement procedure consists of two steps. 1) Determine the time length of supervision and duration of successive supervisions which maximize the minimum point availability for simultaneous supervision schedule where all components are supervised simultaneously. 2) Improve the supervision schedule of Step 1 by constructing a staggered supervision schedule. In this schedule components are divided into subgroups, and supervisions of subgroups are staggered while components in the same subgroup are supervised simultaneously. A systematic method is given to optimize allocating components into subgroups for a specified number of subgroups and staggering of supervisions. An example illustrates the method.

A comparison of the keypeck and treadlepress operants in the pigeon: Differential-reinforcement-of-low-rate yoked variable-interval schedule

Earlier investigations have indicated that the treadlepress response of the pigeon may not be as sensitive as the keypeck to the differential reinforcement of long interresponse times. This study tested the sensitivity of each operant under a multiple differential-rein-forcement-of-low-rate yoked variable-interval schedule that approximately equated reinforcement rate in the two schedule components. Three of four pigeons had much higher response rates in the variable-interval component for both operants, while one pigeon responded at the same rate in both components for both operants. These results showed that both the treadlepress and the keypeck response are similarly affected by the differential reinforcement of long interresponse times.