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.     

Temporal integration in Pavlovian appetitive conditioning in rats

We used an appetitive sensory preconditioning procedure to investigate temporal integration in rats in two experiments. In Phase 1, rats were presented with simultaneous compound trials on which a 10-sec conditioned stimulus (CS) X was embedded within a 60-sec CS A. In Group Early, CS X occurred during the early portion of CS A, whereas in Group Late, CS X occurred during the latter portion of CS A. In Phase 2, CS X was paired simultaneously with sucrose. On a subsequent test with CS A, the rate of magazine entries peaked during the early portions of the stimulus in Group Early and during the latter portions of the stimulus in Group Late (Experiments 1 and 2). Similar response peaks were not observed on tests with a control stimulus that had been presented in compound with a stimulus that did not signal reward (Experiment 2).     

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.     

Territorial behavior of laboratory rats under conditions of peripheral anosmia

Two experiments investigated the influence of peripheral anosmia with zinc sulfate solution on aggressive and nonaggressive behaviors of rats in the colony intrusion paradigm. Experiment I was a replication of a previous observation that anosmic intruders arenot attacked by resident males. No significant differences were found in aggressive response to normal or anosmic intruders. Experiment II tested colony residents under normal and anosmic conditions for aggressive and nonaggressive response to intruders. The results were in agreement with previous reports that anosmia abolishes differential responding between males and females as well as all aggressive acts normally directed against unfamiliar males.     

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.     

Differences in food consumption under intermittent and continuous reinforcement schedules of water delivery: Some implications for schedule-induced behavior

Consumption of food pellets was examined in four water-deprived rats during 1-h sessions in which water was presented once every 30, 60, or 120 sec independently of the rats’ behavior according to three fixed-time (FT) schedules. Correlated with each FT condition was a continuous reinforcement (CRF) control condition in which the rats received, at the start of the session, the number of dipper presentations that were programmed to occur during the corresponding FT condition. During both the FT and CRF conditions, pellets per dipper presentation decreased and food intake rate increased with rate of water presentation, and there was a direct linear relation between log food intake and log water intake. For each of these three measures there was less eating under the FT condition than under the CRF condition, but the difference between the FT and CRF functions decreased at shorter FT values. These data are discussed in terms of the effects of amount of water on food consumption and the principle of temporal summation.     

Stimulus control of behavior during the postreinforcement pause of FI schedules

Pigeons were given the opportunity to terminate certain segments of fixed intervals by pecking a control key. When 30-sec segments of negative and positive stimuli alternated across the interreinforcement interval (Experiment 1), most birds terminated a large proportion of negative segments. However, few control-key responses were made during the negative segment immediately following food presentation. Under schedules during which only one negative segment was programmed, during the first 30 sec of 1-min intervals (Experiment 2), control-key responses, when they occurred at all, were made after several seconds of the interval had elapsed. Similar findings were obtained when a peck on the control key merely changed the color on the food key (Experiment 3). These findings suggest that the post-reinforcement extinction state (Schneider, 1969) during fixed-interval schedules consists of two phases: an immediate postreinforcement inhibitory phase, followed by a second phase during which a control-key response may occur. These two phases and their associated behavior may be related to Staddon’s (1977) distinction between interim and facultative activities.     

Outcome-selective effects of intertrial reinforcement in a Pavlovian appetitive conditioning paradigm with rats

The outcome-selective effects of presenting intertrial unconditioned stimuli (USs) in a rat appetitive conditioning paradigm were examined in two experiments. In both experiments, two stimuli were paired with different outcomes, while one of these outcomes was also presented in the intertrial interval (A+, B*, +). Two measures of learning, stimulus-elicited magazine approach and Pavlovian-to-instrumental transfer, were used to examine these effects. The presence of freely occurring outcomes in the intertrial interval (ITI) was observed to interfere more with the learning of a new association (Experiment 1) and to degrade more an already established association (Experiment 2) when the conditioned stimulus had been paired with the same outcome as that occurring in the ITI. An outcome-selective effect of ITI USs distinguishes among accounts of contingency based on general performance, attentional, and motivational mechanisms from those based on more specific associative mechanisms. Overall, the data highlight the importance of specific encoding processes in the analysis of associative learning.     

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.     

Schedule induction and the temporal distributions of adjunctive behavior on periodic water schedules

The ability of periodic water reinforcement schedules to induce or entrain activities was investigated by having observers classify mutually exclusive and exhaustive activities of 10 rats placed in a rich environment with various fixed-time schedules of water delivery. For each activity measured, three characteristics of induced behavior were examined: (1) its excessiveness; (2) the commonly observed inverted-U relation between rate of induced behavior and rate of reinforcement; and (3) the observation that induced activities occur earlier in interreinforcement intervals than do facultative activities, producing multimodal activity distributions. All activities were demonstrated to be noninduced, facultative activities, and none could be classified as schedule-induced behavior by any of the three criteria. The factors that determine the temporal distributions of all activities appeared to be equivalent to the factors that determine the distributions of scheduleinduced activities in situations in which only the induced activities are available.     

Development of preference and spontaneous recovery in choice behavior with concurrent variable-interval schedules

Pigeons pecked on two response keys that delivered reinforcers on a variable-interval schedule. The proportion of reinforcers delivered by one key was constant for a few sessions and then changed, and subjects’ choice responses were recorded during these periods of transition. In Experiment 1, response proportions approached a new asymptote slightly more slowly when the switch in reinforcement proportions was more extreme. In Experiment 2, slightly faster transitions were found with higher overall rates of reinforcement. The results from the first session, after a switch in the reinforcement proportions, were generally consistent with a mathematical model that assumes that the strength of each response is increased by reinforcement and decreased by nonreinforcement. However, neither this model nor other similar models predicted the “spontaneous recovery” observed in later sessions: At the start of these sessions, response proportions reverted toward their preswitch levels. Computer simulations could mimic the spontaneous recovery by assuming that subjects store separate representations of response strength for each session, which are averaged at the start of each new session.     

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.     

论预期违约的本质

预期违约的本质问题一直是学者争论的焦点之一。国外学者就此问题主要有四种理论，即要约承诺理论、不可能履行理论，隐含条款论，保护履行期待理论。者认为，预期违约在本质上侵犯的是效力不齐备的现实债权，特定物买卖合同而言，出卖方的预期违约又同时侵犯了买受方的物权期待权。     

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.     

论预期违约的分类

我国《合同法》引入了具有典型英美法传统的预期违约制度。预期违约的类型,一直是我国法学理论界的重要讨论话题。文章提出预期违约宜分为明示拒绝履行、默示拒绝履行和预期不能履行三种具体形态,并重点论证了关于默示拒绝履行构成要件和预期不能履行构成要件的观点。