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JOURNAL OF THE EXPERIMENTAL ANALYSIS OF BEHAVIOR

1978, 30, 37-46

NUMBER

I (JULY)

AUTOMAINTENANCE IN GUINEA PIGS: EFFECTS OF FEEDING REGIMEN AND OMISSION TRAINING' ALAN POLING AND TERESA POLING UNIVERSITY OF SOUTH CAROLINA Behavior maintained by stimulus-reinforcer pairings was examined. Guinea pigs maintained at 85 per cent of free-feeding weights reliably contacted a retractable lever presented before delivery of a single piece of guinea-pig chow or a 45-milligram guinea-pig pellet. When animals were given free access to one food and received the second food preceded by the lever, contact responses persisted. Such responses seldom occurred when a single food was freely available and was also delivered after lever presentation. Introduction of an omission training (negative automaintenance) procedure, in which lever contacts resulted in lever retraction and prevented food delivery, strongly reduced lever contacts. Observation indicated that mouthing the food cup, instead of the lever, became the prominent behavior during the prefood stimulus under the omission training procedure. Key words: respondent conditioning, automaintenance, negative automaintenance, omission training, feeding regimen, lever contact, guinea pigs

variety of physiological and biochemical research (see, e.g., Wagner and Manning, 1976). However, experimental psychologists have not intensively studied the species (for reviews see Johnson, Lyle, Edwards, and Penny, 1975; Harper, 1976). In the wild, guinea pigs are bulk-feeding herbivores that spend a large portion of their time consuming grasses and vegetables (King, 1956; Rood, 1972). They apparently do not adapt well to food or water deprivation (Cizek, 1954; Collier, Levitsky, and Weinberg, 1968; Dutch and Brown, 1968), and perhaps as a consequence rarely have been studied under conditions involving severe food or water deprivation. The operant behavior of the species may be maintained under conWilliams, 1969). ditions of moderate deprivation (e.g., PeterThe present research examined automain- son, Ackil, Frommer, and Hearst, 1977; Poling, tamned responding in guinea pigs, a species not Urbain, and Thompson, 1977), or when "prepreviously studied in this context. Guinea ferred" foods are contingently available to anipigs are docile, inexpensive, and relatively mals maintained at free-feeding weights (e.g., long-lived subjects, traditionally favored for a Berryman, 1976). However, it is not clear whether nondeprived or moderately-deprived guinea pigs would consistently respond under 'This research was begun during the senior author's an automaintenance procedure involving retenure as a graduate student at the University of Minnesota, where Richard Meisch and Travis Thompson sponse-independent food presentation. The kindly provided laboratory facilities. Partial support first of the present studies examined the effects for the research was provided by United States Public of feeding regimen on the automaintained reHealth Services Grant MH-08565 and National Institute sponding of guinea pigs. of Health Grants AA00299-06 and DA0084-03. Reprints The second experiment involved the sysmay be obtained from Alan Poling, Psychology Departtematic observation of guinea pigs under automent, The University of South Carolina, Columbia, maintenance and negative automaintenance South Carolina 29210. 37

If a food-deprived pigeon is occasionally presented with an illuminated response key followed by response-independent food, contact responses to the lighted key are reliably engendered and maintained (e.g., Brown and Jenkins, 1968; Gamzu and Williams, 1971, 1973; Schwartz and Williams, 1972b). Automaintained responding, as the responding maintained by a stimulus paired with food delivery is termed, has also been demonstrated in food-deprived chickens, quail, fish, dogs, and monkeys (Hearst and Jenkins, 1974; Schwartz and Gamzu, 1977). Under some conditions, such responding persists under a negative automaintenance procedure, where responding prevents food delivery (Williams and

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ALAN POLING and TERESA POLING

procedures. The topography of the automaintained response typically resembles the unconditioned response elicited by the reinforcer alone (Barrera, 1974; Jenkins and Moore, 1973), although observation of subjects under automaintenance and negative automaintenance procedures indicates that behavior during a prefood or prewater stimulus may include components that do not directly resemble consummatory behavior (Peterson et al., 1972; Stiers and Silberberg, 1974; Wessels, 1974; Woodruff and Williams, 1976). When food is the reinforcer, the nonconsummatory behaviors observed under automaintenance and negative automaintenance procedures usually resemble the natural food-procuring (i.e., "appetitive") behaviors of the organism studied, and appreciable species differences occur. Thus, the behavior of guinea pigs under these procedures may be of some interest. EXPERIMENT I Although previous research (e.g., Cotton, 1953; Cicala, 1961; Shull and Brownstein, 1968) has indicated that animals maintained at free-feeding weights continue to emit operants reinforced by preferred foods, and may even emit food-reinforced operants in the presence of "free" food (the "contrafreeloading effect"-see review by Osborne, 1977), the effects of exposing animals maintained at freefeeding weights to an automaintenance procedure in which food is presented have not been reported. The automaintenance procedure is paradigmatically a respondent conditioning procedure (Brown and Jenkins, 1968; Gamzu and Williams, 1971, 1973; Sclhwartz and Gamzu, 1977), although automaintained responding is sensitive to both operant (response-reinforcer) and respondent (stimulusreinforcer) contingencies (e.g., Barrera, 1974; Deich and Wasserman, 1975; Schwartz and Williams, 1972a; Wasserman et al., 1975; Wessels, 1975; Woodruff and Williams, 1976; Wesp et al., 1977). So long as the food presented is a sufficient unconditioned stimulus to elicit unconditioned (consummatory) responses, pairing an appropriate conditioned stimulus with that food should be sufficient to evoke conditioned responding (Mackintosh, 1974), which might be additionally strengthened via operant contingencies. Experiment I examined automaintained responding in

guinea pigs given free and limited access to food. METHOD

Subjects Three adult male Hartley-derived guinea pigs, individually housed with free access to water in a room maintained at 24°C, received a daily portion of fresh vegetables and Purina Guinea Pig Chow and/or Noyes Guinea Pig Pellets (45 mg) as described below.

A4pparatus A 45- by 45- by 45-cm operant conditioning chamber was constructed of plywood. The chamber was equipped with a 30- by 30-cm one-way mirror mounted in the ceiling to allow direct observation of subjects. The work panel of the chamber was fitted with a metal food cup horizontally centered 2.5 cm above the chamber floor, and two retractable plastic levers 0.6 cm in diameter. One lever was located 4 cm to each side of the food cup, 4 cm above the chamber floor. When extended, the levers protruded 2.5 cm from the work panel. Lever contacts with a horizontal or vertical force of greater than 0.09 N were recorded. A 15-W white light located above the work panel provided constant ambient illumination. Ventilation and masking noise were supplied by an exhaust fan. Electromechanical recording and programming equipment were located outside the chamber. Procedure

During all sessions, a fixed-trial autoshaping procedure, similar to that described by Stiers and Silberberg (1974), was constantly in effect. Under this procedure, each of the two levers was presented for 12 sec under a variable-time 60-sec schedule, in which the interval between successive lever presentations ranged from 30 to 180 sec (with a mean of 60 sec). After 12 sec of presentation of the left (positive, CS+) lever, food was delivered and the lever was withdrawn. The right (neutral, CS') lever was presented and withdrawn randomly with respect to presentations of food and the left lever. Contact responses during presentations of each lever were recorded separately, and had no scheduled effect. Each animal was exposed to one session per day, six days per week. A session terminated after 50 presentations of each lever.

AUTOMAINTENANCE IN GUINEA PIGS During Sessions 1 through 40, animals were maintained at 85% of free-feeding weights. A single 45-mg Noyes Guinea Pig Pellet followed left-lever presentations during Sessions 1 through 30, while a single bit of Purina Guinea Pig Chow (mean weight from a sample of 1000 = 69 mg) followed left-lever presentations during Sessions 31 through 40. Following the fortieth session, animals were given free access to Purina Guinea Pig Chow and Noyes Guinea Pig Pellets in home cages for 12 calendar days at the end of which time their weights had returned to the pre-experiment level. Animals were then re-exposed to an automaintenance procedure. During Sessions 1 through 7, 18 through 24, and 45 through 55 of re-exposure, animals were given unlimited access to Purina Guinea Pig Chow in home cages and experimental chambers (the food was placed on the floor of the chamber), while Noyes Guinea Pig Pellets were delivered only following left-lever presentations. During Sessions 8 through 17 and 25 through 34, unlimited chow was available in home cages and the experimental chamber, and was also delivered after left-lever presentations. During Sessions 35 through 44 and 56 through 65, unlimited pellets were available in home cages and the experimental chamber and were also delivered following left-lever presentations. The sequencing of food availability in home cages and the experimental chamber is shown in Figure 2. RESULTS

Figure 1 shows the percentage of presentations of each lever (trials) that resulted in one or more contact responses when animals were food-deprived. After 10 sessions of exposure to the automaintenance procedure, each guinea pig regularly contacted the left (CS+) lever when it was presented and followed by either a pellet or a bit of chow. For all animals, contacts to the right (CS') lever occurred much less frequently. Figure 2 shows the percentage of presentations of each lever (trials) that resulted in one or more contact responses when feeding regimens were altered. When animals were given unlimited access to either chow or pellets and received the same food following left-lever presentations, relatively few contact responses to either lever occurred. During unlimited access to chow, pellets delivered following left-lever

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presentations maintained contact responses to that lever, but not to the right lever. Pellets were not an effective UCS, however, when the subjects had unlimited access to them. DISCUSSION Experiment I demonstrated automaintained responding in guinea pigs, and also demonstrated that food deprivation sufficient to cause weight loss is not necessary for the maintenance of responding evoked by a prefood stimulus. Previous studies have demonstrated automaintained responding in various species (Schwartz and Gamzu, 1977), and the demonstration of automaintained responding by guinea pigs is thus not particularly surprising. The lack of consistent responding to the right lever, which was presented randomly with respect to food, indicates that it was the pairing of lever presentation and food delivery, not lever presentation per se, that engendered responding (see Rescorla, 1967). This finding is consonant with previous reports (e.g., Gamzu and Williams, 1971, 1973; Peterson et al., 1972) and would be expected if automaintained responding were engendered and maintained via respondent conditioning, as various researchers (e.g., Gamzu and Williams, 1971, 1973; Jenkins, 1973; Moore, 1973; Schwartz and Gamzu, 1977) have contended. Persistent responding under an automaintenance procedure in which food is presented to animals given unlimited access to a second food has not been previously demonstrated, although G. B. Peterson et al. (1972) reported automaintained responding with electrical brain stimulation, a stimulus whose efficacy is not dependent on deprivation in the usual sense, as the reinforcer. If automaintained responding is evoked primarily via respondent conditioning, so long as the food presented elicits unconditioned (consummatory) responses, preceding it by an appropriate conditioned stimulus should evoke conditioned responding (Mackintosh, 1974); the present data support this conclusion. However, the animals used in the present study had acquired the automaintained response when food deprived, and it is not clear whether the response would be acquired and maintained by animals at free-

feeding weights. Studies of operant performance have repeatedly indicated that food deprivation is not a necessary condition for the maintenance of


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responding: various species maintained at freefeeding weights, including guinea pigs, may continue to emit operants reinforced by preferred foods (Berryman, 1976; Cotton, 1953; Cicala, 1961; Shull and Brownstein, 1968). Persistent food-reinforced operant responding also occurs in rats, mice, chickens, crows, cats, gerbils, fish, hamsters, and humans tested in

the presence of freely available food (Osborne, 1977), although guinea pigs apparently have not been studied under this condition. In view of the range of species studied and the lack of reported species differences, however, there is no compelling reason to believe that guinea pigs would not behave similarly. Automaintained and operant responding have been dem-

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Fig. 2. Percentage of lever presentations (trials) in which each lever was contacted during the latter sessions of Experiment I. The UCS food was delivered following left-lever (CS+) presentations, while the food labelled ad lib was freely available in both home cages and experimental chambers. Right-lever (CSO) presentations were random with respect to food delivery. Each lever was presented 50 times per session.

onstrated to be similarly affected by responsedependent and response-independent electric shock (Wesp, Lattal, and Poling, 1977) and d-amphetamine administration (Poling and Thompson, 1977), and the present results suggest that they may be similarly affected by feeding regimen. However, further research involving direct comparison of the effects of feeding regimen on the operant and automaintained responding of guinea pigs is necessary to evaluate the accuracy of this suggestion. EXPERIMENT II Although the automaintenance procedure is paradigmatically a respondent conditioning procedure, a number of studies (e.g., Barrera,

1974; Deich and Wasserman, 1975; Gamzu and Schwam, 1974; Wessels, 1974; Woodruff and Williams, 1976) have shown that automaintained responding is sensitive to operant as well as respondent contingencies. Such demonstrations have often involved the imposition of a negative response-reinforcer dependency, such that responding prevents reinforcer delivery. While some studies have reported that responding is well maintained under this negative automaintenance procedure (Stiers and Silberberg, 1974; Williams and Williams, 1969), others have reported a partial (Barrera, 1974; Schwartz and Williams, 1972a, 1972b) or nearly complete (Gamzu and Schwam, 1974; Hursh et al., 1976; Locurto et al., 1976; Schwam and Gamzu, 1975; Wessels, 1974;

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Woodruff and Williams, 1976) reduction of responding when a negative response-reinforcer dependency was imposed. In addition, the form of the behavior observed during a prefood or prewater stimulus has sometimes (e.g., Stiers and Silberberg, 1974; Woodruff and Williams, 1976), but not always (e.g., Barrera, 1974), been found to change when a negative response-reinforcer dependency was imposed. For example, Stiers and Silberberg (1974) reported that rats licked, pawed, and bit the lever under an automaintenance procedure, but contacted the lever with the nose when a negative automaintenance procedure was instituted. In contrast, Barrera (1974) found that pigeons pecked the response key under an automaintenance procedure, but pecked other areas of the chamber under a negative automaintenance procedure; the spatial locus, but not the form of the response, was altered under the negative automaintenance procedure. The variables controlling behavior under a negative automaintenance procedure seemingly are not well understood. However, the importance of the species studied as a determinant of behavior under both automaintenance and negative automaintenance procedures has been strongly emphasized. In general, under both procedures the behavior observed during a prefood or prewater stimulus resembles the behavior normally associated with procurement and consumption of the reinforcer (e.g., Barrera, 1974; Jenkins and Moore, 1973; Stiers and Silberberg, 1974; Wessels, 1974; Woodruff and Williams, 1976). Schwam and Gamzu (1975) contended that the effects of a negative response-reinforcer dependency depend critically on the relative range of appetitive and consummatory responses of the species studied: pigeons, for instance, simply approach and peck food, while food may evoke a variety of responses by monkeys, including biting, licking, pawing, sniffing, and mouthing. In a species such as the pigeon, where food evokes a relatively rigid response sequence, the form of the behavior observed during a prefood stimulus is not likely to be altered by a negative response-reinforcer dependency, although its spatial locus may be (cf. Barrera, 1974). In the monkey and other species where food evokes a variety of responses, a negative response-reinforcer dependency may alter both the form and the spatial locus of behavior dur-

ing a prefood stimulus. Experiment II involved the systematic observation of guinea pigs, a species whose feeding behavior has been described in some detail (Hirsch and Collier, 1974; King, 1956; Rood, 1972), under automaintenance and negative automaintenance procedures. METHOD

Subjects and Apparatus Subjects and apparatus were as used in Experiment I; subjects were maintained at 85% of free-feeding weights throughout the study. Procedure

During Sessions 1 through 10 and 31 through 50 of this experiment, subjects were exposed to an automaintenance procedure identical to that used in Sessions 1 through 30 of Experiment I. During Sessions 11 through 30 and 51 through 60 of the second experiment, a negative automaintenance procedure was in effect. Under this procedure, contact of the left lever resulted in withdrawal of that lever and prevented food delivery. Contact of the right lever had no scheduled effect. Sessions terminated after 50 presentations of each lever, and occurred once per day, six days per week. During all sessions, each subject was watched by one or both of two observers, who recorded what behavior occurred during leftlever presentations. Four behaviors were systematically observed: (1) mouthing the food cup, (2) mouthing the lever, (3) mouthing other areas of the chamber, (4) grooming (licking the forepaws and/or rubbing the forepaws across the head). Observation of animals during Experiment I indicated these behaviors to occur at relatively high frequencies. Observer A watched 60 sessions alone, observer B watched 60 sessions alone, and 60 sessions were watched conjointly. A percentage measure of interobserver agreement was calculated by dividing the number of left-lever presentations in which the ratings of both observers agreed by the total number of left-lever presentations and multiplying by 100. Overall interobserver agreement was 87%, with a range across sessions of 71% to 97%. Although four behaviors were monitored, only mouthing the food cup and mouthing the lever occurred during more than 10% of leftlever presentations during either the automaintenance or negative automaintenance

AUTOMAINTENANCE IN GUINEA PIGS procedures. Therefore, only data on these behaviors are reported. RESULTS Figure 3 shows the percentage of left-lever presentations (trials) during which each subject mouthed the food cup and the left lever during all conditions of Experiment II. When the automaintenance condition was initially in effect, all subjects regularly mouthed the left lever when it was presented. Institution of the negative automaintenance procedure resulted in a strong decrease in the percentage of leftlever presentations in which that lever was mouthed, and a strong increase in the percentage of left-lever presentations in which mouth-

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Fig. 3. Percentage of lever presentations (trials) in which mouthing the left-lever (CS+) and mouthing the food cup were observed during Experiment II. Under the automaintenance procedure, a pellet was delivered following each left-lever presentation and lever contacts had no scheduled consequences. Under the negative automaintenance procedure, food was delivered following a left-lever presentation only if the lever was not contacted when presented. Each session consisted of 50 presentations of the lever.

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Throughout Experiment II, subjects rarely contacted the right lever, and right-lever contacts were not systematically affected by experimental conditions. Other behavior was not monitored during right-lever presentations. DISCUSSION The responding of guinea pigs was not reliably maintained under a negative automaintenance procedure during the present study. However, the dependency of this finding on the particular parameters studied remains to be determined. In the case of rats and pigeons, responding may (e.g., Stiers and Silberberg, 1974; Williams and Williams, 1969) or may not (e.g., Hursh et al., 1974; Locurto et al., 1976) be maintained under a negative automaintenance procedure, and, for pigeons, whether responding is maintained depends critically on specific experimental parameters (Griffin and Rashotte, 1973). Thus, it is possible that parameters could be found under which guinea pigs would emit contact responses to a prefood stimulus, even though such responses prevented food delivery. However, this was not attempted here. In the present study, institution of a negative automaintenance procedure following exposure to an automaintenance procedure resulted in a shift in the spatial locus, but not in the apparent form, of the behavior most commonly observed during the prefood stimulus: under the former condition during both Experiments I and II, guinea pigs made mouth contacts to the food cup; under the latter they made mouth contacts to the left lever. These results parallel Barrera's (1974) findings with pigeons. They are also similar to the findings of Wasserman (1973), who studied chicks under automaintenance and negative automaintenance procedures with heat as the reinforcer. Under both conditions, pecking and nuzzling of the preheat stimulus was observed. However, contrary to the results of the present study and those of Barrera (1974), Wasserman (1973) found contact responding to be well

maintained under the negative automaintenance procedure. Results of the present study are partially in keeping with Schwam and Gamzu's (1975) contention that animals with relatively rigid prefeeding and feeding behaviors emit similar behaviors under automaintenance and negative automaintenance procedures, since the

feeding and prefeeding behaviors of guinea pigs are known to be simple and relatively stereotyped (King, 1956; Rood, 1972; Smith, 1938). That animals in the present study directed prefood behavior toward the food cup, rather than other areas of the chamber, is interesting but not particularly surprising: the food cup was the only object in the chamber (other than the levers) of a size and shape suitable for mouthing, and mouthing of the food cup occurred at a relatively high frequency during the automaintenance condition. In addition, pellets were delivered into the cup; thus, animals regularly approached it after left-lever (and food) presentations: by virtue of the animal's behavior, the food cup was "associated" with food delivery. Finally, since pellets were delivered there, the food cup might well have been a source of olfactory and/or gustatory stimuli. However, the contribution (if any) of each of these factors to the localization of prefood behavior is not known. GENERAL DISCUSSION Contrary to some earlier reports (see, e.g., Johnson et al., 1977), the present data indicate that guinea pigs are suitable subjects for behavioral research involving moderate food deprivation. Peterson and coworkers (M. R. Peterson et al., 1977) reached a similar conclusion, based on their studies of the operant behavior of the species. The performance of guinea pigs under automaintenance and negative automaintenance procedures was sensitive to respondent and operant contingencies, which is in keeping with the results of a great number of studies (e.g., Gamzu and Schwam, 1974, 1977; Hearst and Jenkins, 1974). Feeding regimen, a variable not previously examined in this context, also influenced automaintained responding although (under some conditions) responding was maintained both in the presence and absence of free food. The predominant behavior observed during a prefood stimulus under automaintenance and negative automaintenance procedures resembled the natural feeding behavior of guinea pigs, which emphasizes the role of species-typical behavior patterns in influencing performance under these procedures (cf. Moore, 1973; Schwam and Gamzu,

1975).

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the Psychonomic Society, 1973, 2, 402-404. Harper, L. V. Behavior (of the guinea pig). In J. E. Wagner and P. G. Manning (Eds), The biology of the guinea pig. New York: Academic Press, 1976. Pp. 31-51. Hearst, E. and Jenkins, H. M. Sign-tracking: the stimulus-reinforcer relation and directed action. Austin, Texas: The Psychonomic Society, 1974. Hirsch, E. and Collier, G. Ecological determinants of reinforcement in the guinea pig. Physiology and

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40-402. Rescorla, R. A. Pavlovian conditioning and its proper control procedures. Psychological Review, 1967, 74, 71-80. Rood, J. P. Ecological and behavioral comparisons of three genera of Argentine cavies. Animal Behavior Monograms, 1972, 5, 1-83. Schwam, E. and Gamzu, E. Constraints on autoshaping in the squirrel nmonkey: Stimulus dimensions and response topography. Bulletin of the Psychonomic Society, 1975, 5, 369-372. Schwartz, B. and Gamzu, E. Pavlovian control of operant behavior. In W. K. Honig and J. E. R. Staddon (Eds), Handbook of operant behavior. Englewood Cliffs: Prentice-Hall, 1977. Pp. 53-97. Schwartz, B. and Williams, D. R. The role of the response-reinforcer contingency in negative automaintenance. Journal of the Experimental Analysis of Behavior, 1972, 17, 351-357. (a) Schwartz, B. and Williams, D. R. Two different kinds of key peck in the pigeon: some properties of responses maintained by negative and positive response-reinforcer contingencies. Journal of the Experimental Analysis of Behavior, 1972, 18, 201-216. Shull, R. L. and Brownstein, A. J. Effects of prefeeding in a fixed-interval reinforcement schedule. Psychonomic Science, 1968, 11, 89-90. Smith, K. U. Behavior of decorticate guinea pigs.

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Journal of Comparative Psychology, 1938, 18, 433447. Stiers, M. and Silberberg, A. Autoshaping and automaintenance of lever-contact responses in rats. Journal of the Experimental Analysis of Behavior, 1974, 22, 497-506. Wagner, J. E. and Manning, P. J. (Eds) The biology of the guinea pig. New York: Academic Press, 1976. Wasserman, E. H. Pavlovian conditioning with heat reinforcement produces stimulus-directed pecking in chicks. Science, 1973, 181, 875-877. Wasserman, E. A., Hunter, N. B., Gutowski, K. A., and Boder, S. A. Autoshaping chicks with heat reinforcement: The role of stimulus-reinforcer and response-reinforcer relations. Journal of Experimental Psychology, 1975, 1, 158-169. Wesp, R. K., Lattal, K. A., and Poling, A. Punishment of autoshaped key-peck responses of pigeons. Jour-

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27, 407-418. Wessels, M. G. The effects of reinforcement upon the pre-pecking behavior of pigeons in the autoshaping experiment. Journal of the Experimental Analysis of Behavior, 1974, 21, 125-144. Williams, D. R. and Williams, H. Automaintenance in the pigeon: sustained pecking despite contingent non-reinforcement. Journal of the Experimental Analysis of Behavior, 1969, 12, 511-520. Woodruff, G. and Williams, D. R. The associative relation underlying autoshaping in the pigeon. Journal of the Experimental Analysis of Behavior, 1976, 26, 1-13.

Received 26 August 1977. (Final acceptance 16 January 1978.)