Pavlovian appetitive conditioning under curare in rats

A CS was paired with rewarding intracranial stimulation while Ss were immobilized by curare. Tests of the activity response to the CS were carried out before and after conditioning. With either simple or discriminative conditioning, activity to the rewarded CS increased after training. These results are comparable to those in studies using food reward and support the hypothesis that a central motivational state is conditioned to stimuli preceding reward.     

The organization and temporal properties of appetitive behavior in rats

In the presence and absence of an externalinterfood clock stimulus (a sequence of flashing lights), rats showed a multimodal behavior pattern during successive quarters of interfood intervals (IFI) ranging from 12 to 192 sec. Responses near the feeder peaked before and just after food presentations, whereas locomotion remote from the feeder peaked toward the middle of the IFI. The temporal patterns of nosing in the feeder and remote locomotion were scalar (the time at which a response peaked in the IFI was proportional to the IFI length), whereas the patterns of postfood feeder-directed behavior, rearing, and pawgrooming were time bound (peaking at a fixed time after food, regardless of IFI length). Responses varied in their control by the external clock stimulus. During the last half of the IFI, rats nosed in the feeder more with an external clock, but only at intermediate IFIs. During the first quarter of the IFI, rats pawgroomed more with an external clock, but only at the longest IFI. The general sequence of responses during the interfood clock was consistent with the view that food delivery engages an organized sequence of search states that are expressed through a variety of responses.     

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.     

Adjunctive behavior in multiple schedules of reinforcement

A recent theory of timing (Killeen & Fetterman, 1988) suggests that adjunctive behaviors may act as discriminative cues for the passage of time and that the rate of transition between those behaviors is affected by the rate of reinforcement within the experimental context. Is the rate of transition between behaviors correlated with the rate of reinforcement? What is the context in which rate of reinforcement is calibrated? If rate of transition is correlated with reinforcement frequency, does this correlation change with extended training? Four pigeons were trained on multiple fixed-time schedules of reinforcement, with one component always FT 15 sec, the other either FT 15 sec, FT 45 sec, or FT 5 sec. Behavior was coded into one of 12 categories. Response distributions in the constant component shifted when rate of reinforcement was varied in the other component and eventually shifted back toward their original location.     

The effects of qualitative and quantitative variation in the US on individual components of Pavlovian appetitive conditioned behavior in rats

The form of rats’ Pavlovian conditioned responses to visual and auditory conditioned stimuli (CSs) paired with a variety of unconditioned stimuli (USs) was examined in three experiments using direct behavioral observation techniques. In Experiment 1, the form of conditioned behavior occurring most frequently during later portions of the CS-US interval depended only on which of several appetitive USs was used, but the form of behavior occurring most frequently during early portions of the CS-US interval depended only on the nature of the CS. US-dependent behaviors resembled the response to the US, and CS-dependent behaviors resembled the original orienting response (OR) to the CS. In Experiment 2, the use of larger magnitude appetitive USs resulted in higher frequencies of US-dependent behaviors, but lower frequencies of CS-dependent behaviors in the presence of auditory and visual CSs. In Experiment 3, US-dependent conditioned behavior to auditory and visual CSs paired with shock was more frequent when high-intensity shocks were used, but CS-dependent behavior was more frequent when low-intensity shocks were used. These results suggested that Pavlovian conditioned responding may involve two independent types of behavior—one appropriate to the US and another based on the original OR to the CS.     

Dissociation of conditioned appetitive and consummatory sexual behavior: Satiation and extinction tests

Sexual responses were conditioned in male Japanese quail using the opportunity to copulate with a female as the unconditioned stimulus (US). The conditioned stimulus (CS) was a 3-D object made of a taxidermically prepared female quail head mounted on a terry-cloth body. Both appetitive conditioned responses (approach and proximity to the CS) and consummatory conditioned responses (mount and cloacal contact directed toward the CS) developed when 2-min presentations of the CS were followed immediately by the US, but not when the CS and US were separated by trace intervals of 10 or 20 min (Experiment 1). Postconditioning sexual satiation suppressed conditioned cloacal contact responses more than conditioned approach to the CS (Experiment 2), and “acute” extinction suppressed both conditioned mounting and conditioned cloacal contact responses more than conditioned approach to the CS (Experiment 3). These results demonstrate a functional dissociation between conditioned appetitive and consummatory responses and imply that the motivational and/or associative mechanisms underlying the two types of behavior are distinct.     

Individualizing schedules of instruction for school children with learning and behavior problems

Current emphasis on developing individual educational plans for children presents a problem of matching one child's educational plan with that of other children and then grouping several such children together for instruction, such that the individual qualities of each child's program are still maintained. Teacher and child variables in a noncategorical program for early childhood education of retarded, autistic, seriously disturbed, learning disabled, and aphasic children were used to generate monthly computerized schedules of instruction for 12–16 children each month. Schedules were generated over an eight-month period, and the last month's weekly schedule was presented for purposes of illustration and discussion. Advantages and feasibility of such a system were discussed.     

Anticipatory socialization of graduate students

Most observers in higher education and most faculty agree that more student-oriented teachers are needed; but there is no consensus on how to get them. Options include finding new faculty and/or changing present faculty. The latter seems practically impossible, since most faculty are intransigent, and faculty development is addressed to too few. Graduate education, too, is unlikely to change, as present faculty guide its directions. The alternative is to find students with the proper dispositions on entrance to graduate schools. The question addressed herein is whether among current admittees to graduate schools there are sufficient numbers of persons with orientations significantly different from those of current faculty. The article reports on empirical assessments of preferences for 320 discrete tasks in the academic role by accepted graduate school applicants and younger and older faculty.This paper was presented at the 17th Annual Meeting of the Association for Institutional Research, Montreal, Canada, May 9, 1977. The research was supported by a grant from the Fund for the Improvement of Postsecondary Education, Department of Health, Education and Welfare.     

The maintenance of matching behavior when contrast occurs in multiple concurrent concurrent schedules of reinforcement

Pigeons were trained on a multiple schedule of reinforcement in which each component was a concurrent schedule. The concurrent schedules were programmed by the changeover-key procedure. The primary purpose was to determine if the relative behavior allocated to two response alternatives is affected when absolute changes in these behaviors occur; i.e., to determine if matching is affected when positive behavioral contrast occurs. Results showed that (1) relative behavior in the unaltered component of the multiple schedule is not disrupted when positive contrast occurs in that component, (2) positive contrast occurred when the overall frequency of reinforcement in the reinforcement-correlated component(s) was high, but not when it was low, (3) changeover behavior was susceptible to positive contrast effects, and (4) changeover contrast and food-key contrast are independent phenomena.     

Habituation may contribute to within-session decreases in responding under high-rate schedules of reinforcement

Two experiments tested the hypothesis that habituation contributes to within-session decreases in responding. In Experiment 1, rats’ leverpressing was reinforced under a fixed ratio (FR) 4 schedule throughout the baseline sessions. During the dishabituation sessions, the first 21 min and the last 21 min were FR 4; dishabituating events occurred during the middle 3 min. The dishabituating events altered the manner of reinforcer delivery in four different ways. Response rates increased after all dishabituating events. In Experiment 2, rats responded on several FR and variable ratio (VR) schedules. The ratio requirement varied from 3 to 15. Within-session decreases in responding were steeper during FR schedules than during VR schedules. In addition, response rates were well described as linear functions of cumulative number of food pellets eaten within sessions. These results support the habituation hypothesis but do not rule out the possibility that other satiety variables might contribute simultaneously.     

中国不安抗辩权与预期违约制度的路径选择

不安抗辩权与预期违约制度是大陆法与英美法各自创设的，旨在规制合同履行风险的法律制度。本主要采用比较的方法对两制度内涵、价值及未来走向进行比较分析。并针对中国《合同法》将两制度规定在同一法律之中而导致的重叠与冲突，提出了自己的建议。作认为，在完善预期违约固有规则的基础上。以预期违约替代不安抗辩权的规定是修改《合同法》的现实路径。     

刍议预期违约制度

早在《合同法》颁布之前,对于预期违约的论述已经在国内引起重大影响。然而,法律界关于预期违约所形成的通说并不符合英美法的制度事实,这对于我国的法律进步必然形成巨大的阻碍。本文详细介绍了英美法的预期违约制度,以此澄清法律界在预期违约制度上所存在的误解,为未来立法完善提供参考。     

Effects of an aversive CS+ and CS− under deprivation upon successive classical appetitive and aversive conditioning

Rabbits under high or moderate water deprivation received in Stage 1 either paired (CS+), unpaired (CS?), or no-tone/shock presentations, with the pairings being appropriate for nictitating membrane conditioning. In Stage 2, all groups were given paired tone and water deliveries for jaw-movement conditioning, while, in Stage 3, all group received the tone and shock paired together for membrane conditioning. In Stage 2, the previously established aversive CS+ suppressed jaw-movement conditioning under high deprivation, and membrane CR decrements were directly related to deprivation. Also in Stage 2, the aversive CS? raised jaw-movement conditioning under moderate deprivation. In Stage 3, membrane CR performance immediately returned in the aversive CS+ group. For the other groups, conditioning was faster under high, relative to moderate, deprivation; however, the initial membrane CR occurrence required more trials if unpaired presentations were used in Stage 1. These results suggest that CSs can acquire both opponent-process and associative effects expressed according to the prevailing training conditions.     

Experiential aspects of exploratory behavior in rats

Twenty-four male rats were reared under three feeding conditions. These conditions manipulated the number and variety of exploratory behaviors required to obtain diets of powdered food and water in feeding boxes. One group performed minimal exploratory responses to obtain their diets. Another group shuttled between two feeding stations, thereby executing several exploratory components, primarily locomotor. The third group performed a considerable number and variety of exploratory components in search of their diets, located unsystematically throughout the feeding box. Adult testing occurred without food and water in an apparatus resembling the feeding boxes. The results showed that exploratory behavior was affected by feeding conditions, enhanced with increased dietary deprivation, and reduced across both trials and within-trial intervals. These results indicate that the particular exploratory behavior measured must be selected by reference to the subjects’ prior experience.     

Concurrent schedules of wheel-running reinforcement: Choice between different durations of opportunity to run in rats

How do animals choose between opportunities to run of different durations? Are longer durations preferred over shorter durations because they permit a greater number of revolutions? Are shorter durations preferred because they engender higher rates of running? Will longer durations be chosen because running is less constrained? The present study reports on three experiments that attempted to address these questions. In the first experiment, five male Wistar rats chose between 10-sec and 50-sec opportunities to run on modified concurrent variable-interval (VI) schedules. Across conditions, the durations associated with the alternatives were reversed. Response, time, and reinforcer proportions did not vary from indifference. In a second experiment, eight female Long-Evans rats chose between opportunities to run of equal (30 sec) and unequal durations (10 sec and 50 sec) on concurrent variable-ratio (VR) schedules. As in Experiment 1, between presentations of equal duration conditions, 10-sec and 50-sec durations were reversed. Results showed that response, time, and reinforcer proportions on an alternative did not vary with reinforcer duration. In a third experiment, using concurrent VR schedules, durations were systematically varied to decrease the shorter duration toward 0 sec. As the shorter duration decreased, response, time, and reinforcer proportions shifted toward the longer duration. In summary, differences in durations of opportunities to run did not affect choice behavior in a manner consistent with the assumption that a longer reinforcer is a larger reinforcer.     

Stimulus- and feeder-directed behavior in a long-box: Effect of fixed versus variable time schedules of food presentation

Two groups of 6 pigeons were exposed to either a fixed-time (FT) or a variable-time (VT) schedule of response-independent food presentation. The interval between two successive food presentations (food-food [FF] interval) was either 20 or 40 sec. The duration of stimulus presentation (stimulus-food [SF] interval) was varied relative to the FF interval. All subjects were exposed to different information ratios (IRs; IR = SF/FF; IR = 1.00, 0.50, 0.15). To study the relative contribution of sign- and goal-tracking behavior to keypecking observed in standard autoshaping procedures, pigeons were autoshaped in a long-box. In the long-box, the stimulus key and the feeder are located 60 cm apart. Stimuli were always presented at one end of the box, and food was presented at the other end. Locomotor behavior and keypecks were recorded. Pigeons engaged in sign-tracking behavior when IR = 0.15, but only when presentation of the food was unpredictable on the basis of other variables (e.g., the passage of time since the last food presentation, as in FT schedules). In the case of FT schedules, subjects engaged in feeder-directed activities. No effects of varying the FF interval were found. Keypecking was observed only when the SF interval was short (IR = 0.15) and food was presented on a VT schedule.     

Operant response topographies of rats receiving food or water reinforcers on FR or FI reinforcement schedules

Separate groups of food- and water-deprived rats pressed a lever for food or water, respectively, on continuous reinforcement and various fixed-ratio and fixed-interval reinforcement schedules. Food-reinforced rats on continuous, FR 2-, or FI 10-sec schedules showed consistently longer mean lever contact durations per leverpress than did water-reinforced rats on the same schedules. Mean lever-contact-duration differences between food- and water-reinforced rats were greatly attenuated or disappeared under FR 4-, FR 8-, FI 20-sec, and FI 30-sec schedules of reinforcement. These results are interpreted as supporting earlier hypotheses that there are respondent components of operantly conditioned and autoshaped leverpresses, but that these respondent components weaken with partial reinforcement and the leverpress topography comes under the control of operant contingencies.     

An opponent-process interpretation of postshock bursts in appetitive responding

While eight food-deprived rats pressed a lever for food during daily 1-h sessions, four CS-Shock₂ trials were presented. Trials were preceded by either a Shock₁ of .25, .50, .75 mA or no Shock₁. It was found that the rate of appetitive responding during the CS was greater on Shock₁-CS-Shock₂ trials relative to CS-Shock₂ trials. The data indicate that the phenomenon of postshock bursts in responding can occur in the absence of a signal for safety after shock. The results conform to the predictions of the opponent-process theory of motivation.     

Blocking and enhancement of fear conditioning by appetitive CSs

Prior research on Pavlovian-to-instrumental transfer has shown that when a CS previously associated with shock (AvCS+) is presented contingent upon a choice response to a discriminative stimulus for food reinforcement, it facilitates discrimination learning. Conversely, a response-contingent CS previously associated with the absence of shock (AvCS?) retards discrimination learning. To evaluate whether these findings reflect across-reinforcement blocking and enhancement effects, two experiments investigated the effects of appetitively conditioned stimuli on fear conditioning to a novel stimulus that was serially compounded with the appetitive CS during conditioned-emotional-response (CER) training. Although there were no differential effects of the appetitive CSs in CER acquisition, Experiment 1, using a relatively weak shock US, showed that a CS previously associated with food (ApCS+) retarded CER extinction to the novel stimulus, in evidence of enhanced fear conditioning to that stimulus. In addition, Experiment 2, using a stronger shock US, showed that a CS previously associated with the absence of food (ApCS?) facilitated CER extinction to the novel stimulus, in evidence of weaker fear conditioning to that stimulus. These results parallel traditional blocking effects and indicate not only that an ApCS+ and an ApCS? are functionally similar to AvCSs of opposite sign, but that their functional similarity is mediated by common central emotional states.     

Frustration and sexual behavior in male rats

Frustration is an emotional state produced by the surprising omission in quantity and/or quality of an appetitive reinforcer. The aversive properties of stressors, such as electric shocks, produce responses similar to those elicited by a state of frustration. In this set of three experiments, we assessed the effects of water immersion (WIM, in Experiment 1)—that is, a physical stressor—and first (in Experiments 1 and 2) and second trials of a consummatory extinction (cE; i.e., a surprising reward omission; in Experiment 3) on the sexual behavior of male rats, as compared with nonstressed animals. The results showed a sexual deficit in the animals subjected to either WIM or cE, relative to control subjects, although these experimental conditions differed in the component of the male sexual response that was affected. The present results accord with the fear = frustration hypothesis, and with Amsel’s frustration theory.