Social discrimination and aggressive pecking in domestic chicks.

Free interaction among 192 White Leghorn chicks involved inter-S pecking. During tests as early as 1 day after hatching, socially reared Ss showed reliable social discriminations by pecking more at strangers than at cage mates. Compared with socially reared birds, Ss reared in isolation exhibited certain exaggerated or atypical response patterns. Patterns included heightened rates of inter-S pecking, a pronounced tendency to peck at the head, elevated emotionality as reflected in the distress call, and the failure of pair-mates to show matched rates of environmental pecking. Inferences are drawn from these patterns, with the conclusion that infantile inter-S pecking in chicks may be based on aggressive rather than strictly exploratory tendencies. Findings are discussed in terms of the development of a basic tolerance for conspecifics and early social orderings. (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanisms for social transmission of pecking preferences to neonatal chicks.

An arrow, motor driven to make "pecking" movements, released and directed pecking by 412 1-day-old domestic chickens. Stimuli (colored plastic pinheads) placed on or near the arrow tip resulted in pecking selectively directed to matching stimuli. Innate color and position preferences, a preference for stimuli with low environmental density, and a possible tendency of Ss to peck toward the center of a mass of peck-releasing stimuli were experimentally eliminated as explanations for the phenomenon. Other unsatisfactory explanations include reinforcement effects, social facilitation, and local enhancement. Arrow-directed pecking developed over trials, persisted after removal of arrow-operation and/or model stimuli, and required for acquisition only visual exposure to modeling conditions. Results demonstrate the operation of a mechanism for transmission of abstract information about the visual characteristics of food objects from hen to chicks. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Form of early pecking in the ring dove squab (Streptoplia risoria): An examination of the preformation hypothesis.

Investigated the components of pecking in adult and squab ring doves. A very precise gape transduction system was used to collect normative data and examine the hypothesis that food pecking develops prefunctionally, that is, without related experience. In Exp 1, adult gapes were characterized as a function of pellet size. In Exp 2, squab's gapes during early attempts to feed were examined. These gapes were not very similar to the adult form and were poorly coordinated with head thrusts. In Exp 3, contributions of maturation to the development of the food peck were assessed. Squab raised on powdered grain received Pavlovian pairings of the sight of whole grain with feedings. Induced pecks had gapes that were not similar to the adult form and displayed poor coordination with thrust. It is concluded that task-specific experience is needed for the development of the adult food peck. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The acquisition of stimulus control over released pecking by hatchling chicks (Gallus gallus).

Analyzed the spatial and dynamic stimulus characteristics of the pecking arrow display that control simple release and/or learned release of pecking by 254 hatchling chicks in 5 experiments. Findings show (1) a pronounced preference by Ss to peck at red rather than green illuminated lamps, (2) significantly greater pecking by Ss to lamps attached to, and on the floor beneath, the pecking arrow during the display, and (3) little evidence that placement of a stimulus on the arrow, on the floor beneath the arrow, or in both locations differentially affected frequency of pecking to matching stimulus colors. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanisms underlying the effects of unsignaled delayed reinforcement on key pecking of pigeons under variable-interval schedules

Three experiments were conducted to test an interpretation of the response-rate-reducing effects of unsignaled nonresetting delays to reinforcement in pigeons. According to this interpretation, rates of key pecking decrease under these conditions because key pecks alternate with hopper-observing behavior. In Experiment 1, 4 pigeons pecked a food key that raised the hopper provided that pecks on a different variable-interval-schedule key met the requirements of a variable-interval 60-s schedule. The stimuli associated with the availability of the hopper (i.e., houselight and keylight off, food key illuminated, feedback following food-key pecks) were gradually removed across phases while the dependent relation between hopper availability and variable-interval-schedule key pecks was maintained. Rates of pecking the variable-interval-schedule key decreased to low levels and rates of food-key pecks increased when variable-interval-schedule key pecks did not produce hopper-correlated stimuli. In Experiment 2, pigeons initially pecked a single key under a variable-interval 60-s schedule. Then the dependent relation between hopper presentation and key pecks was eliminated by arranging a variable-time 60-s schedule. When rates of pecking had decreased to low levels, conditions were changed so that pecks during the final 5 s of each interval changed the keylight color from green to amber. When pecking produced these hopper-correlated stimuli, pecking occurred at high rates, despite the absence of a peck-food dependency. When peck-produced changes in keylight color were uncorrelated with food, rates of pecking fell to low levels. In Experiment 3, details (obtained delays, interresponse-time distributions, eating times) of the transition from high to low response rates produced by the introduction of a 3-s unsignaled delay were tracked from session to session in 3 pigeons that had been initially trained to peck under a conventional variable-interval 60-s schedule. Decreases in response rates soon after the transition to delayed reinforcement were accompanied by decreases in eating times and alterations in interresponse-time distributions. As response rates decreased and became stable, eating times increased and their variability decreased. These findings support an interpretation of the effects of delayed reinforcement that emphasizes the importance of hopper-observing behavior.     

Hippocampal response patterns during discriminative eyeblink/jaw movement conditioning in the rabbit.

Rabbits were given concurrent training in eyeblink (EB) and jaw movement (JM) conditioning in which 1 tone predicted an airpuff and another tone predicted water. After 10 days of discrimination training, the animals were given 10 days of reversal training. In the discrimination phase, acquisition of the 2 conditioned responses was not significantly different; however JM discrimination errors were much more frequent than were EB errors. In the reversal phase, correct performance on EB trials increased gradually, as was expected, whereas there was immediate behavioral reversal on JM trials. Differences in size and topography of dorsal CA1 multiple-unit responses reflected the ability of the hippocampus to discriminate between stimuli in trained animals, corresponding to the performance of the behavioral discrimination. During JM trials, the rhythmicity of the neural response was further modulated by the type of the prior trial, suggesting the coding of sequential events by the hippocampus. Thus, hippocampal conditioned activity can rapidly change its magnitude and pattern depending on the specific trial type during a concurrent EB/JM discrimination task and its reversal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Radiosensitive period of pecking response during embryological development of domestic chicks.

Gave gamma irradiation to 174 cross-bred chick embryos on Days 2-12 of incubation in 2-day steps. A 5-fold increase in between-Ss variance and a 3-fold increase in within-Ss variance resulted when Ss were tested with induced pecking responses, but only in groups treated on Days 6 and 8. There were no difference in variances between groups treated on any other day nor in the controls. It is claimed that comparison of means is an inappropriate and misleading test for treatment effects. Results are discussed in terms of both raised thresholds and loss of negative feedback in the response system. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The dynamics of conditioning and extinction.

Pigeons responded to intermittently reinforced classical conditioning trials with erratic bouts of responding to the conditioned stimulus. Responding depended on whether the prior trial contained a peck, food, or both. A linear persistence–learning model moved pigeons into and out of a response state, and a Weibull distribution for number of within-trial responses governed in-state pecking. Variations of trial and intertrial durations caused correlated changes in rate and probability of responding and in model parameters. A novel prediction—in the protracted absence of food, response rates can plateau above zero—was validated. The model predicted smooth acquisition functions when instantiated with the probability of food but a more accurate jagged learning curve when instantiated with trial-to-trial records of reinforcement. The Skinnerian parameter was dominant only when food could be accelerated or delayed by pecking. These experiments provide a framework for trial-by-trial accounts of conditioning and extinction that increases the information available from the data, permitting such accounts to comment more definitively on complex contemporary models of momentum and conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of backward pairings on the conditioning of the albino rabbit's jaw movement and nictitating membrane responses.

Evaluated backward conditioning of appetitive jaw movement and aversive nictitating membrane responses in rabbits, using 3 procedures: test trials, forward acquisition of the same response, and crossmotivational acquisition of the other response system. In both experiments, backward conditioning consisted of 3 conditioned stimulus/stimuli (CS) alone and 22 CS and unconditioned stimulus/stimuli (UCS) pairings. Contrasting the backward conditioning group with explicitly unpaired and no-treatment controls revealed that backward pairings produced no associative effects. The forward acquisition and crossmotivational acquisition tests suggest that excitatory backward acquisition of jaw movement was obtained. The forward acquisition test identified weak inhibitory conditioning of nictitating membrane responses, but the crossmotivational test implicated excitatory conditioning. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pavlovian and instrumental determinants of response suppression in the pigeon.

Exp I demonstrated the formation of a discriminated punishment effect in the absence of a conditioned emotional response. Electric shocks were delivered at random intervals to 3 naive male White Carneaux pigeons pecking for food on a variable-interval schedule. During a 1-min visual conditioned stimulus (CS), scheduled shocks were delayed until a response occurred (punishment). Differential suppression to the CS was observed in addition to overall suppression. Suppression was related to shock intensity. In Exp II with the same Ss, CS suppression was related to the CS and was not an artifact of response pattern or discrimination of shock patterns. The punishment contingency without the CS did not suppress behavior, and the CS without the punishment contingency did not relieve suppression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Food-deprivation level alters the effects of morphine on pigeons' key pecking

Four pigeons pecked response keys under a multiple fixed-ratio 30 fixed-interval 5-min schedule of food presentation. Components alternated separated by 15-s timeouts; each was presented six times. Pigeons were maintained at 70%, 85%, and greater than 90% of their free-feeding weights across experimental conditions. When response rates were stable, the effects of morphine (0.56 to 10.0 mg/kg) and saline were investigated. Morphine reduced response rates in a dose-dependent manner under the fixed-ratio schedule and at high doses under the fixed-interval schedule. In some cases, low doses of morphine increased rates under the fixed-interval schedule. When pigeons were less food deprived, reductions in pecking rates occurred at lower doses under both schedules for 3 of 4 birds compared to when they were more food deprived. When pigeons were more food deprived, low doses of morphine increased rates of pecking in the initial portions of fixed intervals by a greater magnitude. Thus, food-deprivation levels altered both the rate-decreasing and rate-increasing effects of morphine. These effects may share a common mechanism with increased locomotor activity produced by drugs and with increased drug self-administration under conditions of more severe food deprivation.     

Development of food recognition in young chicks: IV. Associative and nonassociative effects of experience.

In 4 experiments, 3-day-old Burmese Red Junglefowl chicks were allowed to peck food, sand, or mealworms or were force-fed liquid food, glucose water, or water and were tested later on either food or sand. Only experience that involved pecking led to the development of a discrimination between food and sand based on short-term metabolic feedback. These and previous results can be accounted for by postulating that the act of pecking and a hunger coordinating mechanism develop independently but experience is necessary for the association of pecking with the hunger system (i.e., chicks must learn that pecking leads to ingestion). After this association is formed, unlearned physiological mechanisms could modulate the rate of pecking directly. Immediate discrimination between food and sand, based on taste cues, occurred when chicks had 3 separate experiences in ingesting food. This result can be accounted for by using a standard discrimination learning paradigm. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feather pecking in domestic chicks: its relation to dustbathing and foraging

Feather pecking is a serious problem in poultry housing, as it may lead to feather damage, injuries and even mortality. We tested predictions of the two prevalent hypotheses claiming that feather pecking is related to dustbathing and foraging, respectively. Forty-two groups of 30 laying hen chicks, Gallus gallus domesticuswere reared in pens with a slatted floor. Access to sand as a dustbathing substrate and straw as a foraging substrate was varied between groups. The rate of feather pecking was measured in early development up to week 7. The provision of a sand area did not prevent the chicks from developing high rates of feather pecking that caused injuries. Chicks that had access to sand from day 10 showed higher rates of feather pecking than chicks that had access to sand from day 1. The provision of straw to chicks that had developed high rates of feather pecking led to a decrease in this behaviour. Chicks that could use both sand and straw from day 1 on did not show high rates of feather pecking, and no injuries were observed in these groups. There was no significant difference in dustbathing activity between housing conditions characterized by high or low rates of feather pecking. On the other hand, foraging activity was inversely related to the rate of feather pecking, and the occurrence of feather pecking could be delayed from week 4 to week 7 by postponing procedures that led to changes in foraging behaviour. In conclusion, the results show that the presence of an appropriate substrate for dustbathing does not prevent domestic chicks from developing feather pecking. On the other hand, housing conditions that promote foraging behaviour are effective in reducing and preventing feather pecking.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour     

Sensitization to cocaine in pigeons: Interaction with an operant contingency.

A 2-part study with pigeons investigated the role of an explicit operant contingency in determining how cocaine interacts with locomotor activity. In Part 1, pigeons pecked on a fixed-ratio-20 schedule of food presentation. In Part 2, different pigeons were studied without opportunity to peck for food. After determination of cocaine's initial effects, pigeons were exposed to daily administrations of a locomotion-increasing dose of cocaine. Locomotor sensitization was evident in the pigeons of Part 2, and tolerance developed to cocaine's effects on key pecking in the pigeons of Part 1. Locomotor sensitization was generally not evident in the pigeons of Part 1. These results suggest that explicitly conditioned operant behavior may compete with behavior sensitized by prolonged exposure to cocaine. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Similarity of approach and pecking preferences for spectral stimuli in domestic chicks: Absence of a mirror-image relation.

Reports that the results of H. H. Schaefer and E. H. Hess (1959) showing that White Rock chicks described mirror-image response functions to spectral stimuli in approach and pecking behavior could not be replicated using 10 Cornish-Cross chicks under more controlled conditions. Present results show similar blue-orange bimodal functions for both behavioral responses, resembling the approach data of Schaefer and Hess and the earlier pecking data of Hess and others, but not the pecking data reported by Schaefer and Hess. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of initial-pecking consequences on subsequent pecking in young chicks.

White Leghorn cockeral chicks ? and 2? days old received saline or LiCl injection immediately following their 1st feeding experience. When retested 5 hrs later 2?-day-old Ss that had received saline increased their pecking rate, but ?-day-old Ss showed no change. Only 2?-day-old chicks, therefore, appear to associate ingestion of food with long-term positive consequences. Ss of both ages, on the other hand, greatly reduced pecking when retested 5 hrs after LiCl injection. Thus, ?- and 2?-day-old chicks are capable of forming an association between pecking and its long-term consequence when the consequence is aversive. When LiCl injection was not contingent on pecking, following the initial feeding session by 6 hrs, Ss did not reduce retest pecking rates. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Components of aggression in chickens and conceptualizations of aggression in general.

A refined analysis of the peck order in chickens is offered as a test of the notion that, for this species, different responses such as leaping and various types of pecking need not be interchangeable indexes of aggression. Tests showed that particular response types of the birds were differentially mediated by organismic or environmental factors. 36 pairs of male and female White Leghorn chicks were assigned to large cages, and 48 pairs were assigned to small cages. In large cages pecking at the body was most frequent by Ss that had a home-cage advantage. Contrarily, rates of aggressive leaping were independent of this influence, with males having an advantage over females. Males showed more head pecking than females, but the profile for this sex difference did not resemble the profile for leaping. Correlational analyses revealed that whereas head pecking between testmates was not matched in frequency, leaping was positively related. The behavior of Ss in small cages differed from that of large-cage Ss. Although there was more head pecking in small cages, males did not have an edge, and leaping was infrequent. Results indicate that these responses cannot be viewed as interchangeable indicators of aggression in fowl. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pigeons' spatial memory: IV. Effects of intertrial interval manipulations on delayed matching of key location.

In Exp I, the effect of intertrial interval (ITI) duration on 3 Silver King pigeons' delayed matching of key location was investigated. Trials began with a ready stimulus (brief operation of the grain feeder); then one randomly chosen key from a 3?×?3 matrix was lit briefly as the sample. After a delay (retention interval) of 1, 4 or 8 sec, the sample key was lit again, along with another key. A peck at the key that had served as the sample (correct comparison) produced food reinforcement, whereas an incorrect peck led directly to the ITI. The ITI was 2.5 or 25 sec. Matching accuracy was lower at the shorter ITI and was linearly related to the log of the ratio of the ITI to the delay interval. In Exp II, noncontingent food reinforcement presented during the 25-sec ITI lowered matching accuracy of 5 Ss. In Exp III, reinforcement was given for pecking a key (correct, incorrect, or irrelevant) presented during the ITI. Reinforcement for pecking any key had a facilitative effect on matching accuracy. Results are discussed in relation to models of spatial memory, the apparent parallels between processes in delayed matching and classical conditioning, and the notion that expectancy of reinforcement during the matching trial facilitates accurate choice of the correct key. (French abstract) (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assay of bropirimine in rat plasma by means of robotic solid-phase extraction and high-performance liquid chromatography

Vacuous jaw movements induced by the muscarinic agonist pilocarpine and striatal dopamine depletions were examined using a slow motion videotape system. With this procedure, rats were videotaped in a Plexiglas tube so that the profile of the head region could be seen. Vacuous jaw movements were analyzed by examining the tape at 1/6 normal speed. An observer recorded each jaw movement using a computer, and the computer program re-calculated the temporal characteristics of jaw movement responses back to normal speed. The interresponse time was recorded for each jaw movement, and each jaw movement interresponse time was assigned to a 50 ms wide time bin. Thus, the distribution of interresponse times could be used to analyze the temporal characteristics of jaw movement responses. In the first experiment, rats were administered saline vehicle, 1.0 mg/kg and 2.0 mg/kg pilocarpine. The rats were videotaped 10-15 min after injection, and the data were analyzed as described above. Pilocarpine induced very high levels of vacuous jaw movements, and the vast majority of all movements occurred in "bursts" with interresponse times of 1.0 s or less. Analysis of the interresponse time distributions showed that most of the jaw movements were within the 150-350 ms range. The modal jaw movement interresponse time was in the 150-200 ms range, which corresponds to a local frequency of 5-6.66 Hz. In the second experiment, the neurotoxic agent 6-hydroxydopamine was injected directly into the ventrolateral striatum in order to produce a local dopamine depletion. The dopamine-depleted rats were observed for jaw movements 7 days after surgery. The overall level of jaw movement activity resulting from dopamine-depletion was much lower than that produced by pilocarpine. There was a significant inverse correlation between ventrolateral striatal dopamine levels and total number of vacuous jaw movements. Videotape analysis indicated that the temporal characteristics of jaw movements induced by dopamine depletions were similar to those shown with pilocarpine. These experiments indicate that vacuous jaw movements induced by pilocarpine and striatal dopamine depletion occur in a frequency range similar to that shown in parkinsonian tremor.     

Key-peck probability and topography in a concurrent variable-interval variable-interval schedule with food and water reinforcers

The relation between variables that modulate the probability and the topography of key pecks was examined using a concurrent variable-interval variable-interval schedule with food and water reinforcers. Measures of response probability (response rates, time allocation) and topography (peck duration, gape amplitude) were obtained in 5 water- and food-deprived pigeons. Key color signaled reinforcer type. During baseline, response rates and time allocations were greater to the food key than to the water key, and food-key pecks had larger gapes and shorter durations. Relative probability measures (for the food key) were increased by prewatering and decreased by prefeeding. Deprivation effects upon topography measures were apparent only when food- and water-key pecks were analyzed separately. Food-key gape amplitudes increased with prewatering and decreased with prefeeding. The clearest effect occurred with prewatering. There were no consistent effects upon water-key gapes. The key color-reinforcer relation was reversed for 3 pigeons to determine how response topography was modulated during the transition from food- to water-key pecks. Reacquisition was faster for the probability than for the topography measures. Analysis of gape-amplitude distributions during reversal indicated that response-form modulation proceeded through the generation of intermediate gape sizes.