Rate Of Key Pecking Research Articles

THE ROLE OF INTERMITTENT FOOD IN THE INDUCTION OF ATTACK IN PIGEONS

The present experiments evaluated whether transitions in reinforcer probability are necessary to induce attack in pigeons. In Experiment I, three of six pigeons exposed to response-contingent constant-probability food schedules and a photograph of a conspecific as a target exhibited sustained postreinforcement attack on the target. The postreinforcement pattern of attack developed over the course of the experiment and was accompanied by a reduction in the rate of postreinforcement key pecking and an increase in the postreinforcement pause in key pecking. These effects on key pecking resulted in unprogrammed variations in the probability of reinforcement which may have been responsible for the induction of attack. In Experiment II, the attack-inducing properties of a constant-probability response-independent food schedule were compared to a periodic food schedule matched for overall rate of food delivery and to a no-food condition. In addition to attack, the spatial location of the subjects was monitored during each interfood interval. The periodic and aperiodic food schedules generated very different patterns of spatial location. Postfood attack was induced by both food schedules, although the constant-probability schedule induced attack in fewer birds. The no-food condition was not effective in inducing attack in any birds. These experiments indicate that intermittent food schedules without reductions in reinforcer probability are sufficient to induce attack in some pigeons, although not as effective as schedules with transitions in reinforcer probability.

Chronic Δ9-tetrahydrocannabinol administration and schedule-induced aggression

The effects of 0.5 mg/kg and 1.0 mg/kg of Δ 9-tetrahydrocannabinol ( Δ 9-THC) on key-pecking maintained by a response—initiated fixed interval (FI) schedule of food presentation and schedule-induced aggression in the pigeon were studied. Initially, following the administration of Δ 9-THC both the rate of key-pecking and attack responding were markedly reduced. Over sessions, tolerance developed to the suppressant effect on key-pecking, with the rate returning to the predrug level. The suppressing effect of Δ 9-THC on the rate of attack remained at or near zero throughout the series of Δ 9-THC injections.

A functional analysis of collateral behavior under differential-reinforcement-of-low-rate schedules

The collateral behavior of pigeons under differential-reinforcement-of-low-rate (DRL) schedules was evaluated for its role in controlling DRL performance. Two of three pigeons engaged in high rates of collateral keypecking under schedules up to DRL 28 sec. Rate of collateral pecking was positively correlated with DRL efficiency. Topographical features of the collateral behavior were inconsistent with the notion that collateral behavior mediates DRL performance through response-produced stimuli. Rather, the collateral behavior appeared to interfere with the operant response, delaying it long enough to meet the DRL requirement.

Behavioral toxicology of carbon disulfide and toluene.

Organic solvents are pervasive in the communal and industrial environments. Although many are potent central nervous system agents, clearly delineated behavioral effects have played only a minor role in the formation of exposure standards. A comprehensive behavioral pharmacology and toxicology of these compounds is one aim of US/USSR collaboration. The current report describes some actions of carbon disulfide and toulene. Earlier data about the actions of carbon disulfide on pigeon operant performance indicated disruption of schedule-controlled key-pecking. Primate data are now described from a situation designed to determine aversive thresholds to electrical stimulation. Effective concentrations of carbon disulfide produced both a rise in the amount of electric shock tolerated and a diminution of the response force exerted by the monkeys. In experiments with toluene, pigeons were shown to elevate key-pecking rate in an operant situation at certain concentrations. Toluene also was studied for its capacity to maintain self-administration in the same way as drugs of abuse. Monkeys worked to gain access to toulene vapor just as they work for opiates or amphetamines. The current experiments demonstrate how comprehensive the range of behavioral toxicology needs to be to deal with environmental health issues.

Prediction of concurrent keypeck treadle-press responding from simple schedule performance

Four pigeons pecked keys and pressed treadles for food reinforcers delivered by several variable-interval schedules of reinforcement. Then the subjects responded on several concurrent schedules. Keypecking produced reinforcers in one component, and treadle-pressing produced reinforcers in the other. The changeover delay, which prevented reinforcement after all switches from one response to the other, was 0, 5, or 20 sec long. An equation proposed by Kerrnstein (1970) described the rates of treadle-pressing and keypecking emitted during the variable-interval schedules. The k parameter of this equation was larger for keypecking than for treadle-pressing. The R0 parameters were not systematically different for the two responses. The rates of keypecking and treadle-pressing emitted during the components of the concurrent schedules correlated with, but were not equal to, the rates of responding predicted by Herrnstein’s equation and the subject’s simple schedule responding. The ratios of the rates of responding emitted during, and the ratios of the time spent responding on, the components of the concurrent schedules conformed to an equation proposed by Baum (1974), but not to Herrnstein’s equation.

Latencies on response-initiated fixed-interval schedules: Effects of signaling food availability

Three pigeons were trained on a response-initiated fixed-interval schedule of food reinforcement where the first keypeck in the presence of one key color changed the key color and started a fixed time interval, after which a keypeck produced food. The latency to begin the fixed-interval component was an increasing function of the fixed-interval duration, which was either 40 or 80 sec. At both interval durations, a condition was also studied where the key color changed again at the end of the fixed interval, signaling the availability of food reinforcement. Adding the signal reduced the rate of keypecking during the fixed-interval component but did not systematically affect the initial latency to start the fixed-interval component.

Response-Contingent Visual Exposure to Conspecific and Social Influence on Key Pecking in Japanese Quail

Operant key pecking was assessed in eight adult male Japanese quail (Coturnix coturnix japonica). Subjects could peck either of two response keys to obtain bird chow reinforcement. In addition, one of the keys controlled visual exposure to conspecifics by altering illumination in a companion compartment adjacent to the subject. One, two, or no companion quail were present. Pecks on the “companion” key started or maintained exposure to companions. Results indicated that (a) subjects reduced significantly the frequency of pecks maintaining companion exposure when companion quail were actually present, (b) cumulative duration of exposure to companions was significantly lower when companions were present, and (c) the overall rate of key pecking was inhibited significantly during exposure to companions. These data contribute to the establishment of a mediating link between observed social inhibition of food-reinforced key pecking and apparent lack of subject preference for visual exposure to conspecifics during operant testing.

ASSOCIATIVE INTERACTION: JOINT CONTROL OF KEY PECKING BY STIMULUS‐REINFORCER AND RESPONSE‐REINFORCER RELATIONSHIPS

The joint control of rate of key pecking in pigeons by stimulus-reinforcer and response-reinforcer relationships was studied in the context of a two-component multiple schedule of reinforcement. Food presentation was always associated with one component and extinction with the other. The stimulus-reinforcer relationship was manipulated by varying the relative durations of the two components. In the food-presentation component, a fixed rate of reinforcement, independent of rate of responding, was generated by a schedule referred to as "T*". One aspect of the response-reinforcer relationship, contiguity, was manipulated by varying the percentage of delayed reinforcers. With the multiple T* extinction schedule, stimulus-reinforcer and response-reinforcer relationships could be varied independently of one another. Rate of key pecking was sensitive to manipulations of both relationships. However, significant differential effects due to either the stimulus-reinforcer or response-reinforcer relationship were obtained only when the other relationship was weak: stimulus-reinforcer and response-reinforcer relationships interacted in the joint control of responding.

Autoshaping the pigeon’s keypeck in a dark chamber

Pigeons were exposed to an autoshaping procedure in a dark chamber with a punctate conditioned stimulus signaling response-independent food presentations. Contrary to other findings, a high rate of autoshaped keypecking emerged and was sustained in all subjects. Although these results support a cue localization hypothesis, they also implicate the importance of the context in which a conditioned stimulus is presented in the autoshaping paradigm.

BEHAVIORS OBSERVED DURING S‐ IN A SIMPLE DISCRIMINATION LEARNING TASK1

Key pecking of pigeons was reinforced with food in the presence of a horizontal line and never reinforced in the presence of a vertical line. Highly stereotyped behaviors, as well as key pecking, were observed and recorded in the presence of both stimuli. Results showed that a high proportion of time spent in the presence of the horizontal line was occupied by key pecking, a high proportion of time in the presence of the vertical line was occupied by stereotyped nonkey-pecking behaviors, and intermediate proportions of time spent in the presence of intermediate stimuli were occupied by each class of behavior during generalization tests. Similar running rates (number of key pecks divided by observed key-pecking time) were obtained in the presence of all stimuli, indicating that changes in time rather than tempo accounted for the changes in overall rates of key pecking. An exception occurred in responding to the horizontal line as differential performance was developing. In addition to an increase in time spent key pecking, increased running rates occurred in seven of eight birds, suggesting that both time allocation and tempo play a role in behavioral contrast of overall rates of key pecking.

Drug effects on fixed-interval responding with pause requirements for food presentation.

In pigeons performing under a multiple schedule of food presentation, low key-pecking rates (0.18 to 0.29 responses per second) were maintained during 3-min fixed-interval components by requiring a 4-, 5-, or 6-sec pause preceding the food-delivery response (tandem DRL), while higher rates (0.70 to 1.37 responses per second) were maintained in alternative fixed-interval components by requiring a pause of no more than 40 msec preceding the food-delivery response (tandem DRH). Thus, reinforcement density was equal but overall response rates markedly different in the two schedule components. Pentobarbital (3, 10 mg/kg) had effects on overall rates of responding consistent with a rate-dependency interpretation (low rates were increased while higher rates were decreased), but d-amphetamine (0.03 to 3 mg/kg) either failed to increase low overall rates in the tandem DRL components or increased them only slightly. Effects of both drugs on local responding within the fixed-intervals were always related in an orderly way to control response rate, but the extent of rate increases produced by d-amphetamine was modifed in some birds by pause requirements such that the drug increased comparable rates less when these occurred in the tandem DRL component than when they occurred in the tandem DRH components. Control rate is an important determinant of drug effects, independent DRH components. Control rate is an important determinant of drug effects, independent of reinforcement density maintaining rates, and independent of environmental influences, such as response-spacing requirements for food presentation, that can modify the extent of some drug-produced rate changes.

INTERACTIONS IN MULTIPLE SCHEDULES: THE ROLE OF THE STIMULUS‐REINFORCER CONTINGENCY1

In Experiments I and II, pigeons were exposed to single-key multiple schedules of response-independent and -dependent food presentation. Components were correlated with different keylights. When the rate of food presentation in the first component exceeded that in the second component, the local rate of key pecking was relatively high at onset of the first component. Overall rate in that component varied inversely with component duration and the rate of food presentation in the second component. When responding was maintained in the second component, the local rate of key pecking was relatively low at onset of that component. Overall rate in the second component varied directly with component duration and the rate of food presentation in that component. In Experiment III, pigeons were exposed to a two-key multiple schedule. Pecks on a constantly illuminated key produced food. Components were correlated with the color of a second key on which pecks had no scheduled consequences. The effects of component duration and rate of food presentation under the single-key response-dependent schedule were synthesized by combining response rates on each concurrently available key under the two-key procedure. The results support an account of multiple-schedule interactions in terms of the joint influence on responding of stimulus-reinforcer and response-reinforcer contingencies.

SOME VARIABLES AFFECTING RATE OF KEY PECKING DURING RESPONSE‐INDEPENDENT PROCEDURES (AUTOSHAPING)1

Rate of key pecking by pigeons subjected to response-independent procedures in which a stimulus on the response key preceded food presentation was investigated in eight experiments. Color and shape of the stimulus, duration of the stimulus, probability of food following the stimulus, duration of the intertrial interval, and duration of food presentation were varied separately and in combination. All variables studied, except color and shape of the stimulus, had a reliable effect on pecking rate, but some variables had stronger effects than others. Rapid key pecking may be obtained with a variety of response-independent procedures, as well as by response-dependent reinforcement. The results of experiments in which food is both dependent on key pecking and correlated with stimulus conditions are not representative of simple operant effects. Key pecking is an ideal response for studying the simultaneous operation of response-reinforcer and stimulus-reinforcer effects.

KEY PECKING IN PIGEONS PRODUCED BY PAIRING KEYLIGHT WITH INACCESSIBLE GRAIN1

In Experiment I, keylight was paired with inaccessible grain delivery (under two conditions of keylight intensity) to determine if autoshaping would occur in the absence of primary reinforcement. In Experiment II, the procedure was repeated with accessible grain, for comparison. In Experiment III, the procedures were repeated with explicitly unpaired presentations of keylight and either inaccessible or accessible grain. The results indicated that key pecking occurred as quickly in the presence of keylight pairings with inaccessible grain as with accessible grain, though (except for one bird) key pecking was not maintained with inaccessible grain. Furthermore, compared to the dim keylight, the bright keylight greatly suppressed key pecking when paired with inaccessible grain, and reduced the rate of key pecking when paired with accessible grain. Little key pecking occurred in groups exposed to explicitly unpaired presentations of keylight (whether bright or dim) and grain (whether accessible or inaccessible). When the birds in Experiment III were retested with explicitly paired presentations of keylight and grain, little key pecking was observed, suggesting suppressive effects of prior explicitly unpaired presentations. It is suggested that the effects of key-brightness manipulation were produced by the association of grain with cues other than the response key, or by distraction produced by partial illumination of the grain hopper.

REINFORCEMENT OF BEHAVIORAL PATTERNS: SHAPING A SCALLOP1

Temporal patterns of key pecking by pigeons were shaped by a schedule in which the delivery of food was contingent upon a measure of the overall extent to which the temporal pattern of behavior within a 5-sec trial conformed to a required pattern. This pattern approximated a constant rate of change in the rate of key pecking throughout the 5-sec trial. In comparison with behavior maintained by a classical fixed-interval 5-sec schedule, the new schedule controlled a better approximation to a "scallop" within individual trials and greatly reduced intersubject variability. These results are consistent with the view that the delivery of a reinforcer after a behavioral pattern a few seconds in duration may strengthen the entire pattern as a unit, or operant. The response topography contiguous with reinforcement may be a negligible fraction of the strengthened operant. One implication of this view is that mean response rate for such brief responses as key pecks and lever presses is a byproduct of whatever patterns are strengthened, and generally will not reveal fundamental controlling relationships, whenever a reinforcer is not contiguous with all the behavior on which it is contingent.

Interactions between carbon monoxide and d-amphetamine or pentobarbital on schedule-controlled behavior

Although carboxyhemoglobin values for the venous blood of pigeons exposed to carbon monoxide (CO) for 1.5 hours were similar to values obtained in other species exposed to the same CO concentrations, the schedule-controlled behavior (multiple fixed-ratio fixed-interval schedule) of the pigeon was relatively insensitive to the effect of CO. However, when the effects of d-amphetamine or pentobarbital on schedule-controlled behavior were studied in the presence of various concentrations of CO, interesting interactions were observed. CO blocked increases in the rate of key pecking produced by d-amphetamine or pentobarbital and enhanced decreases in the rate of responding produced by d-amphetamine, and to some extent by pentobarbital. CO enhanced the effects of pentobarbital on the temporal pattern of key pecking during the fixed-interval component of the schedule, but the effects of d-amphetamine on this temporal pattern were not enhanced by CO.

DEVELOPMENT AND MAINTENANCE OF ATTACK IN PIGEONS DURING VARIABLE‐INTERVAL REINFORCEMENT OF KEY PECKING1

Key-peck responses of two pigeons were maintained on variable-interval schedules of food reinforcement in the presence of a stuffed pigeon to study the characteristics of attack induced by that schedule. The mean interval of the schedule was increased from 15 sec to 600 sec in eight steps before an intermediate interval was reintroduced. The principal characteristics of attack were: (1) substantial attack first occurred on a variable-interval schedule of 90 sec in one pigeon and at 180 sec in the other, (2) the highest attack rates occurred on variable-interval schedules of 300 sec and 600 sec, (3) attack rate generally increased to a maximum and then decreased to a lower level across sessions at each schedule, (4) attacks developed a postreinforcement locus across the initial sessions on all schedules and, except on variable-interval schedules of 300 and 600 sec, occurred primarily in the postreinforcement period during extended training, (5) attack rates and key-peck rates were not recovered when the intermediate-length schedules were reintroduced, and (6) attack rate and key-peck rates were negatively correlated. Except for the fact that the maximum attack rates occurred at interfood intervals of 300 and 600 sec, and that attack and key-peck rates were negatively correlated, these findings have counter-parts in experiments with other reinforcement schedules.

EFFECTS OF RESPONSE RATE, REINFORCEMENT FREQUENCY, AND THE DURATION OF A STIMULUS PRECEDING RESPONSE‐INDEPENDENT FOOD1

Food-reinforced key pecking in the pigeon was maintained under a four-component multiple schedule. In two components, responding was maintained at high rates under a random-ratio schedule. In the other two components, responding was maintained at low rates under a schedule that specified a minimum interresponse time. For both high and low response rates, one of the schedule components was associated with a high reinforcement frequency and the other components with a lower reinforcement frequency. During performance under these schedules, a stimulus terminated by access to response-independent food was periodically presented. The duration of this pre-food stimulus was 5, 30, 60, or 120 sec. Changes in rate of key pecking during the pre-food stimulus were systematically related to baseline response rate and the duration of the stimulus. Both high and low response rates were increased during the 5-sec stimulus. At longer stimulus durations, low response rates were unaffected and high response rates were decreased during the stimulus. For two of three pigeons, high response rates maintained under a lower frequency of reinforcement tended to be decreased more than high response rates maintained under a higher reinforcement frequency. In general, the magnitude of decrease in high response rates was inversely related to the duration of the pre-food stimulus.

Effects of Δ1-tetrahydrocannabinol on schedule-induced aggression in pigeons

The effects of Δ 1-tetrahydrocannabinol ( Δ 1-THC) on key-pecking maintained by a response-initiated fixed interval (FI) schedule of food presentation and schedule-induced aggression in the pigeon were studied. The rate of attack responses was suppressed more than the rate of key-pecking, relative to their vehicle control rates, following the administration of Δ 1-THC (Experiment 1). In order to determine if the relatively selective effect of Δ 1-THC on attack rate was the result of a rate-dependent drug effect, the rates of key-pecking and attack responding were equated prior to drug administration in Experiment 2. Again a selective decrease in the rate of attack responses by Δ 1-THC, compared to its effects on key-pecking, was observed when the rate of the two behaviors was comparable. The suppressing effect of Δ 1-THC on attack responses cannot be attributed to a generalized motor impairment, since doses of Δ 1-THC (0.125 and 0.25 mg/kg) which had little or no effect on the rate of key-pecking resulted in substantial decreases in the rate of attack responses.

RESPONSE DECREMENTS PRODUCED BY EXTINCTION AND BY RESPONSE‐INDEPENDENT REINFORCEMENT1

The effects of extinction and of response-independent (free) reinforcement in decreasing rates of key pecking by pigeons were compared in single schedule (Phase 1) and multiple (Phase 2) conditions. In both phases, response rates decreased more rapidly with extinction than with free reinforcement conditions. Behavioral contrast was obtained from subjects trained in a multiple schedule involving extinction in Phase 2, whereas subjects trained in a multiple schedule involving free reinforcement showed a slight negative induction effect. Whether subjects experienced extinction or free reinforcement under single stimulus conditions did not affect subsequent performance in the discrimination situation of the second phase. Disinhibition testing was carried out at the end of both phases, but there was no evidence for disinhibitory effects under any condition.