共查询到20条相似文献，搜索用时 78 毫秒
1.
William P. Bellingham Katy Gillette-Bellingham E. James Kehoe 《Learning & behavior》1985,13(2):152-164
Discrimination between a tone + light compound and its components in positive and negative patterning schedules was examined. In the positive schedule, reinforced compound presentations (C+) were intermixed with unreinforced component presentations (T?, L?). In the negative schedule, the compound was unreinforced (C?) and the components were reinforced (T+, L+). In Experiment 1, appetitive conditioning of rats’ anticipatory magazine responses was used, and in Experiment 2, aversive conditioning of the rabbit’s nictitating membrane response was used. Both experiments revealed that the positive patterning schedule consistently produced rapid acquisition of appropriate discriminative responding. The results of the negative patterning schedule were more complex. Specifically, the results of Experiment 1 demonstrated that naive rats initially showed rapid acquisition of the negative patterning discrimination. However, schedule reversals revealed that experience with the positive patterning schedule virtually abolished subsequent acquisition of discriminative responding under the negative patterning schedule. The results of Experiment 2 revealed that naive rabbits showed very slow acquisition of discriminative responding under the negative patterning schedule. The results are discussed in relation to the unique-stimulus hypothesis, a contextual encoding hypothesis, and a configural hypothesis. 相似文献
2.
A. G. Baker 《Learning & behavior》1990,18(1):59-70
Three experiments were designed to study the effects of contextual conditioning on the extinction of instrumental leverpressing that had been reinforced on a random-interval schedule. In Experiment 1, noncontingent food retarded extinction, but signaling food delivery, a treatment that should reduce contextual conditioning, reduced the interference. Experiment 2 replicated the results of Experiment 1 and demonstrated that if the food preceded rather than followed the signal, the retardation of extinction was not reduced but was enhanced. In Experiment 3, non-contingent leverpressing was used to directly verify that the three treatments—forward signaling, noncontingent food, and backward signaling—differentially influenced contextual conditioning. Forward signaling produced the least, and backward signaling produced the most, contextual conditioning. This monotonic relationship between contextual conditioning and interference with extinction was used as evidence to support the argument that context-food associations are important in controlling instrumental responding. 相似文献
3.
Conditioned suppression in rats is often unaffected when the context (or set of background stimuli) is changed following conditioning. This suggests that responding to the conditioned stimulus (CS) can be relatively insensitive to the context in which the CS is presented. In two experiments, we examined whether sensitivity to contextual stimuli is affected by preexposure to the CS. In Experiment 1, when the CS was novel at the outset of conditioning, conditioned suppression was not affected when the context was changed following conditioning. However, when the CS had been preexposed, responding was weaker when extinction occurred outside of the conditioning context. In Experiment 2, responding was again sensitive to the test context, regardless of whether preexposure occurred in the conditioning context or in an alternate context. These results suggest that the extent to which responding is sensitive to context can depend on the conditioning history of the CS. 相似文献
4.
Eighteen Long-Evans rats were exposed to a MULT VT 30-sec EXT schedule of water presentations. The EXT schedule was signaled by a 2500-Hz, 70-dB tone. Mean number of bites of a plastic target during atone (S?) increased across sessions, whereas the mean number of target bites during the VT component signaled byno tone (S+) decreased across sessions. Changing the multiple schedule to MULT EXT EXT produced a decrease in target bites during the tone. Reinstating the original MULT VT 30-sec EXT schedule produced an increase in number of target bites during the tone (S?). Changing the multiple schedule to VT 30-sec VT 30-sec produced a decrease in target bites during the tone. The results indicate that target biting in rats increases in the presence of the exteroceptive tone (S?) of the MULT VT 30-sec EXT schedule, and that target biting during the tone varies directly with the negative correlation between tone and water presentations. 相似文献
5.
Three experiments with rat subjects examined the effects of contextual stimuli on performance in appetitive conditioning. A 10-sec tone conditioned stimulus (CS) was paired with a food-pellet unconditioned stimulus (US); conditioning was indexed by the observation of headjerking, a response of the rat to auditory stimuli associated with food. In Experiment 1, a context switch following initial conditioning did not affect conditioned responding to the tone; however, when the response was extinguished in the different context, a return to the original conditioning context “renewed” extinguished responding. These results were replicated in Experiments 2 and 3 after equating exposure to the two contexts (Experiment 2) and massing the conditioning and extinction trials (Experiment 3). The results of Experiment 1 also demonstrated that separate exposure to the US following extinction reinstates extinguished responding to the tone; this effect was further shown to depend at least partly on presenting the US in the context in which testing is to occur (Experiments 2 and 3). Overall, the results are consistent with previous data from aversive conditioning procedures. In either appetitive or aversive conditioning, the context may be especially important in affecting performance after extinction. 相似文献
6.
Chana K. Akins 《Learning & behavior》1998,26(4):416-426
Three experiments were conducted to investigate direct and modulatory influences of context in the conditioned sexual behavior of male Japanese quail. A preference test procedure was used to assess the acquisition of contextual excitation. In Experiment 1, following direct context-unconditioned stimulus (US) pairings, male quail shifted their contextual preference from an initially preferred context to one in which they received copulatory opportunity with a female quail (US). Unpaired control group subjects did not demonstrate this shift in preference. This place preference procedure was used in Experiments 2 and 3 to assess contextual excitation when context was trained in the presence of a discrete conditioned stimulus (CS). Experiment 2 provided evidence that context can modulate responding to a discrete CS. In Experiment 3, we varied the spatial contiguity between the context and the US. Some subjects received the US directly in the training context, whereas other subjects received the US in an alternate context. Contextual excitation was evident only in subjects that received the former. Thus, there is a dissociation between the modulatory and excitatory properties of context in sexual conditioning that may depend on the context-US spatial contiguity. 相似文献
7.
Two studies used a one-trial-a-day aversive conditioning procedure with rats as subjects to investigate the effects of a noise versus a light CS on conditioned freezing. Experiment 1 demonstrated that less conditioned freezing was elicited by the light, although the two CSs led to similar levels of freezing to the contextual cues of the conditioning chamber. Experiment 2 replicated these outcomes and showed that the manipulation of CS intensity produced results similar to those of modality, with the more intense CSs eliciting less freezing. The second experiment also determined that freezing to contextual cues resulted from context conditioning. According to the Rescorla-Wagner model, CSs that condition poorly should generate little competition with context conditioning. Since neither the modality nor intensity factor reliably influenced context conditioning, as measured by context-evoked freezing, the studies provide no support for the view that the effects on CS-evoked freezing represent differences in the strength of conditioning to the various stimuli. This finding raises the possibility that all of the CSs conditioned well but varied in their abilities to elicit freezing because they differed in terms of the form of defensive behavior under their control. 相似文献
8.
In Experiment 1, rats were allowed to acquire either schedule-induced drinking or schedule-induced wood-chewing behavior under a fixed-interval (FI) 60-sec schedule of food reinforcement, following which food was omitted from 20% and then 50% of interreinforcement intervals. Omission of food severely disrupted induced drinking but had relatively little effect on induced wood-chewing. Experiment 2 investigated wood-chewing as a function of reinforcement rate, using a range of FI schedules from 5 to 180 sec in duration. Both the amount of chewing per session and the relative time spent chewing were bitonically related to reinforcement rate. In Experiment 3, schedule-induced chewing that had been acquired under a response-dependent schedule was found to persist under a response-independent schedule. Induced wood-chewing resembles other induced behaviors in important respects, but quantitative differences are also apparent. 相似文献
9.
In three experiments, rats received presentations of a diffuse 30-sec stimulus (a light) and of food, and their tendency to enter the food tray was monitored. Experiment 1 showed that when the light was made to signal the delivery of food, the response of entering the food tray increased in frequency during the stimulus. The acquisition of this conditioned response to the light was retarded in subjects that had received preexposure to the stimulus. In Experiments 2 and 3, subjects received preexposure to the stimulus, some in the same context as that subsequently used for stimulus-food pairings and some in a different context. Those experiencing the change of context acquired the response more readily. It is argued that these results demonstrate a latent inhibition effect that is attenuated by contextual change. 相似文献
10.
Rats injected with lithium chloride after ingesting familiar food pellets presented in textured metal sleeves learned aversions to the sleeved food. In a choice between sleeved and unsleeved food, the aversions were evident following conditioning with toxicosis delayed as long as 120 min after exposure to the sleeved food (Experiment 1). Texture-specific aversions resulted from procedures in which rats were exposed to food in both rough- and smooth-textured sleeves but were injected with lithium only in conjunction with one of the textures (Experiments 2–4). This differential aversion learning occurred when lithium treatment was delayed 30 min after exposure to the sleeved food (Experiments 3 and 4) and was equally evident in rats conditioned and tested in total darkness or in normal room-level illumination (Experiment 4). However, differential texture aversion learning was not observed with 90- or 300-min delayed toxicosis (Experiment 3). The present experiments highlight the importance of tactile cues in the poison-avoidance learning of species that handle their food during the course of ingestion. 相似文献
11.
Rick Richardson Tania Q. Duffield Glynis K. Bailey R. Frederick Westbrook 《Learning & behavior》1999,27(4):399-415
Rats were shocked in the black but not the white compartment of a shuttlebox and then exposed to the black compartment in the absence of the shock unconditioned stimulus (US) to extinguish fear responses (passive avoidance). In five experiments, rats were then shocked in a reinstatement context (distinctively different from the shuttlebox) to determine the conditions that reinstate extinguished fear responding to the black compartment. Rats shocked immediately upon exposure to the reinstatement chamber failed to show either reinstatement of avoidance of the black compartment or fear responses (freezing) when tested in the reinstatement chamber. In contrast, rats shocked 30 sec after exposure to the reinstatement chamber exhibited both reinstatement of avoidance of the black compartment and freezing responses in the reinstatement chamber (Experiment 1). Rats shocked after 30 sec of exposure to the reinstatement chamber but then exposed to that chamber in the absence of shock failed to exhibit reinstatement of the avoidance response and did not freeze when tested in the reinstatement chamber (Experiment 2). Rats exposed to a signaled shock in the reinstatement chamber and then exposed to that chamber in the absence of shock also failed to exhibit reinstatement of the avoidance response (Experiment 5). These rats showed fear responses to the signal but not to the reinstatement chamber. Finally, rats exposed for some time (20 min) to the reinstatement chamber before shock exhibited reinstatement of the avoidance response but failed to freeze when tested in the reinstatement chamber (Experiments 3 and 4). These results are discussed in terms of the contextual conditioning (Bouton, 1994) and the US representation (Rescorla, 1979) accounts of postextinction reinstatement. 相似文献
12.
Nancy A. Marlin 《Learning & behavior》1981,9(4):519-523
Rats were given tone-footshock pairings with a 0-, 10-, or 30-sec trace interval between tone offset and shock onset. Half the rats within each trace interval were tested for their conditioned fear of the tone through a lick suppression procedure; the remaining rats were evaluated for their fear of the background or contextual cues through their avoidance of the compartment in which conditioning had occurred. Less conditioning was observed to the tone with increasing trace intervals. However, conditioned fear of the context increased with increases in the trace duration. The ability of the more predictive stimulus, the tone, to overshadow the contextual cues was determined by the tone’s temporal contiguity with the footshock. The need to incorporate temporal parameters within current theories of conditioning is discussed. 相似文献
13.
Ben A. Williams 《Learning & behavior》2002,30(1):1-20
Behavioral contrast is defined as a change in response rate during a stimulus associated with a constant reinforcement schedule,
in inverse relation to the rates of reinforcement in the surrounding stimulus conditions. Contrast has at least two functionally
separable components: local contrast, which occurs after component transition, and molar contrast. Local contrast contributes
to molar contrast under some conditions, but not generally. Molar contrast is due primarily to anticipatory contrast. However,
anticipatory contrast with respect to response rate has been shown to be inversely related to stimulus preference, which challenges
the widely held view that contrast effects reflect changes in stimulus value owing to the reinforcement context. More recent
data demonstrate that the inverse relation between response rate and preference with respect to anticipatory contrast is due
to Pavlovian contingencies embedded in anticipatory contrast procedures. When those contingencies are weakened, anticipatory
contrast and stimulus preference are positively related, thus reaffirming the view that the reinforcing effectiveness of a
constant schedule is inversely related to the value of the context of reinforcement in which it occurs. The underlying basis
of how the context of reinforcement controls reinforcement value remains uncertain, although clear parallels exist between
contrast and the effects of contingency in both Pavlovian and operant conditioning. 相似文献
14.
Robert A. Rescorla 《Learning & behavior》1997,25(2):200-209
In five experiments, rats were given Pavlovian pairings of auditory and visual stimuli with delivery of food pellets. Experiment 1 found greater responding to an AB compound after training with the individual A and B stimuli, compared with responding both to the A and B elements and to a separately trained CD compound. Experiment 2 found this enhanced responding to depend on the associative strengths of A and B. In Experiment 3, responding was greater to a CD compound than to the other compounds after an AB-, AD+, BC+ training procedure. In Experiment 4, responding to an AB compound was greater than that to the elements after A was reinforced on a 100% schedule and B on a 50% schedule. In Experiment 5, responding to an AC compound was greater than that to either A or C after an AB+, CD+, A-training procedure. A configural theory, such as that proposed by Pearce (1987), anticipates summation in none of these procedures, unless the conditioned context is assumed to have a salience greater than zero. In order to predict summation in Experiments 3, 4, and 5, a context salience greater than that of the elements must be assumed. However, such an assumption also anticipates that extinction of a 100% stimulus should eliminate responding to a 50% stimulus. The results of Experiment 3 contradicted that prediction. These results conform better to the expectations of elemental models of conditioning. 相似文献
15.
The problem was to determine how rats adjust the times of their lever responses to repeating sequences of interfood intervals. In Experiment 1, rats were trained on an interval schedule of reinforcement with a 12-element Fleshler-Hoffman series with a mean of 60 sec; the order was as follows: ascending, random with repetition, random with replacement, random without replacement. In Experiment 2, rats were trained with a 10-element ascending or descending series (from 20 to 29 sec), and in a ramp procedure in which these intervals increased and then decreased repeatedly. In the ascending, descending, and ramp conditions (but not in the random conditions), postreinforcement pause (PRP) was a function of the interval. PRP was most highly correlated with an interval later in the series. Theories of conditioning and timing based on the averaging of past experience must be modified to account for such anticipatory behavior. 相似文献
16.
Two experiments were run in order to investigate the influence of external contextual cues on the interaction between two conflicting memories. Rats were trained, in the same apparatus, on a passive-avoidance task and, 10 min later, on an active-avoidance task, then submitted to a 24-h delayed test (without reinforcement). When contextual cues remained unchanged throughout these three phases, the animals exhibited proactive interference, as shown by longer response latencies than those of control animals that had learned only the active-avoidance task (Experiment 1). When training contexts were made slightly different from one task to the other (by the presence of a continuous tone during either the first or the second task), the animals behaved at subsequent testing in accordance with the response contingencies present in the context exactly similar to the test context; this control of behavior by testing context was demonstrated both when the tone was absent (Experiments 1 and 2) and present (Experiment 2) at testing. A cuing procedure—a 90-sec exposure to the tone in the experimental room 5 min prior to testing—led the animals to behave in accordance with the response previously acquired in the presence of the tone (Experiments 1 and 2), exactly in the same way as animals tested in the presence of the tone (Experiment 2). The same cuing treatment was ineffective when administered 1 h before testing (Experiment 2). These results are interpreted in terms of a dual function of contextual cues at the time of retrieval: the general contextual information present during testing or during pretest cuing is assumed to induce concurrent reactivation of both memories. Consequently, the experimentally manipulated contextual cue (the tone) would have a discriminative function, leading the animals to choose between the two equally available representations. 相似文献
17.
In two experiments, the hypothesis that frustration mediates the production of schedule-induced polydipsia was tested. In Experiment I, a group in which reward was reduced from 6 to 2 pellets of food in an operant chamber was found to increase water intake compared to a group maintained at 2 pellets reward. In Experiment II, rats trained to approach food on a partial reinforcement schedule in a runway subsequently showed lower levels of water intake in the operant test for polydipsia than rats given continuous reinforcement during runway training. The results are interpreted as supporting a frustration hypothesis of schedule-induced polydipsia and are discussed within the context of persistence theory. 相似文献
18.
Jesus Landeira-Fernandez Michael S. Fanselow Joseph P. Decola Jeansok J. Kim 《Learning & behavior》1995,23(3):335-339
Theimmediate shock deficit refers to the failure of a shock to become associated with contextual stimuli when the shock is presented simultaneously with the rat’s placement in a context. The basic procedure consists of a presentation of the shock as soon as the animal is placed in an observation chamber. Handling of the animal, which immediately precedes the shock, and the novelty of the chamber in which the immediate shock is delivered are potential variables that might be responsible for this associative deficit. In Experiment 1, handling reduced context conditioning but was not responsible for the immediate shock deficit. Experiment 2 revealed that the novelty of the chamber was not a significant factor. These results discount the possibility that handling and the novelty of the chamber are responsible for the deficit produced by the immediate shock. It is suggested that immediate shock could be employed as a control procedure for the study of context conditioning. 相似文献
19.
In two experiments, the marine molluskHermissenda crassicornis was exposed to context discrimination training. In one context, defined by the presence of a diffuse chemosensory stimulus (shellfish extract A), brief, unsignaled, unconditioned stimuli (USs; high-speed rotation) were presented; in a second context, defined by the presence of shellfish extract B, no USs were presented. Animals were then tested (at both 1.5 and 24 h) by exposing them to small pieces of the shellfish meat used to define the two contexts. The latency to strike at the meat served as an index of the context-US association. In Experiment 1, the latency to strike at the cue associated with rotation was reduced relative to both preconditioning strike latencies and the associatively neutral cue. However, in a two-choice test where the animals could approach the conditioned or neutral stimulus, the animals regularly avoided the stimulus paired with rotation. Moreover, if, following conditioning, the animals were presented with an unsignaled rotation in the conditioned context or the neutral context, the animals exhibited more effective defensive clinging (an unconditioned reflex normally elicited by rotation) in the conditioned context, suggesting that it “prepared” the animal for the aversive US. In total, these results demonstrate thatHermissenda is capable of making associations to diffuse background (contextual) stimuli. Moreover, the results suggest that pairing the chemosensory cue with an aversive US elicits a strike response inHermissenda when the animal is placed in forced contact with the cue and an active avoidance response when the animal can choose between that cue and a neutral cue. 相似文献
20.
Four experiments were performed to explore the role of context in operant extinction. In all experiments, leverpressing in
rats was first reinforced with food pellets on a variable interval 30-s schedule, then extinguished, and finally tested in
the same and a different physical context. The experiments demonstrated a clear ABA renewal effect, a recovery of extinguished
responding when conditioning, extinction, and testing occurred in contexts A, B, and A, respectively. They also demonstrated
ABC renewal (where conditioning extinction and testing occurred in contexts A, B, and C) and, for the first time in operant
conditioning, AAB renewal (where conditioning, extinction, and testing occurred in contexts A, A, and B). The latter two phenomena
indicate that tests outside the extinction context are sufficient to cause a recovery of extinguished operant behavior and,
thus, that operant extinction, like Pavlovian extinction, is relatively specific to the context in which it is learned. AAB
renewal was not weakened by tripling the amount of extinction training. ABA renewal was stronger than AAB, but not merely
because of context A’s direct association with the reinforcer. 相似文献