共查询到20条相似文献，搜索用时 40 毫秒
1.
Two experiments were conducted to investigate functional similarities between “hunger CRs” of Konorski’s (1967) model of appetitive classical conditioning and sign-tracking behavior in rats. Konorski’s model predicts that hunger CRs will be facilitated (1) when a nonrein-forced stimulus similar to the reinforced CS is introduced, and (2) when some CS presentations are unexpectedly nonreinforced. In Experiment 1, hungry rats acquired a leverpress response to a retractable lever that was paired with response-independent food. Following this training, a second lever was introduced whose presentation was not followed by food. The effect of the presence of this second lever was to facilitate responding to the original lever. In Experiment 2, single-lever autoshaping training was followed by a shift from 100% pairing of the lever with food to only 50% of the lever presentations being followed by food. The introduction of partial reinforcement produced an immediate and durable increase in leverpressing. The findings of both experiments are consistent with predictions from Konorski’s model of classical conditioning if sign-tracking is considered as a “hunger CR.” 相似文献
2.
Two experiments are described, which involved the investigation of interactions between the nature of the conditioned stimulus (CS) and the nature of the unconditioned stimulus (UCS) in producing signal-centered behavior. In Experiment 1, rats received response-independent heat reinforcement in a cold environment. For some groups, this heat UCS was signaled by presentations of a standard aluminum retractable lever; for other groups, it was signaled by a retractable lever covered in acrylic fur (furry lever CS). Only the subjects that received the furry lever CS paired with heat exhibited differential CS-contact behavior, when compared with unpaired, aluminum lever, and warm control subjects. In Experiment 2, hungry rats received pairings of either an aluminum or a furry lever with food (UCS). When compared with unpaired controls, only the subjects that received the aluminum lever paired with food showed differential signal-directed behavior; the subjects receiving the furry lever CS did not show differential contact with the CS, but instead exhibited differential food tray entry behavior during CS presentation. In the two studies, the signal-directed behavior exhibited by subjects resembled either thermoregulatory or feeding behaviors characteristic of rats. The results suggest that signal-directed behavior is determined by a complex interaction between the ecological relevance of the CS and the nature of the UCS—an interaction that can best be described in terms of a behavior systems model of conditioned responding. 相似文献
3.
Peter C. Holland Judith S. A. Asem Connor P. Galvin Caitlin Hepps Keeney Melanie Hsu Alexandra Miller Vivian Zhou 《Learning & behavior》2014,42(1):1-21
Rats will approach and contact a lever whose insertion into the chamber signals response-independent food delivery. This “autoshaping” or “sign-tracking” phenomenon has recently attracted considerable attention as a platform for studying individual differences in impulsivity, drug sensitization, and other traits associated with vulnerability to drug addiction. Here, we examined two basic stimulus selection phenomena—blocking and overshadowing—in the autoshaped lever pressing of rats. Blocking and overshadowing were decidedly asymmetrical. Previously reinforced lever-extension conditioned stimuli (CSs) completely blocked conditioning to auditory cues (Exps. 1 and 2), and previously nonreinforced lever-extension CSs overshadowed conditioning to auditory cues. By contrast, conditioning to lever-extension CSs was not blocked by either auditory (Exp. 3) or lever-insertion (Exp. 4) cues, and was not overshadowed by auditory cues. Conditioning to a lever-insertion cue was somewhat overshadowed by the presence of another lever, especially in terms of food cup behavior displayed after lever withdrawal. We discuss several frameworks in which the apparent immunity of autoshaped lever pressing to blocking might be understood. Given evidence that different brain systems are engaged when different kinds of cues are paired with food delivery, it is worth considering the possibility that interactions among them in learning and performance may follow different rules. In particular, it is intriguing to speculate that the roles of simple cue–reinforcer contiguity, as well as of individual and aggregate reinforcer prediction errors, may differ across stimulus classes. 相似文献
4.
Four experiments examined the influence of a stimulus presented after one response in a two-lever choice task. In Experiment 1, food-deprived rats trained on a concurrent variable-interval extinction schedule responded more often on the extinction lever when such responding periodically produced a visual stimulus than when it did not. In Experiments 2 and 3, a similar signal-induced enhancement effect was found even when food was delivered randomly with respect to responding on both levers or when no food was presented. In Experiment 4, a response-contingent visual stimulus elevated responding to the lever on which it was presented, but an auditory cue suppressed responding. These findings indicate that visual stimuli may possess intrinsically reinforcing properties for rats. 相似文献
5.
In four experiments, we examined how the spatiotemporal proximity to food of the two elements of a serial conditioned stimulus (CS) influenced the pattern of CS-directed versus food-site-directed behavior in rats. Experiment 1 showed that only temporal proximity affected responding when the serial CS consisted of two successive 4-sec presentations of either a spatially near or a spatially far lever (NN or FF). However, Experiment 2 showed that behavior depended markedly on whether rats received a near followed by a far lever (NF) or a far followed by a near lever (FN). Experiment 3 showed that the effects of Experiment 2 could be changed by increasing the duration of the second CS element, and Experiment 4 showed that these changes were not related to previous training. We concluded that behavior produced by the spatiotemporal qualities of the lever elements can be attributed to a mapping between the temporal qualities of the CS elements and an underlying sequence of search modes related to finding food. 相似文献
6.
John H. Hull 《Learning & behavior》1977,5(2):207-212
Experiments 1, 2, and 3 showed that food-deprived rats responding for food pellets made significantly more long-duration leverpresses than water-deprived rats responding for water drops. These experiments further showed that this difference in instrumental response topography is long-lived, and depends neither upon idiosyncrasies of the experimental chamber nor upon severity of deprivation conditions. In Experiment 4, food-deprived rats responding for food pellets made significantly more long-duration leverpresses than did either food- or water-deprived rats responding for sucrose solution. Human judges in Experiment 5 were able to correctly identify instrumental leverpress responses by rats as being for food or water based solely on previous viewings of other rats drinking water or eating food pellets. It appears that instrumental response topographies in rats vary depending principally upon the reinforcer received, and that these instrumental response topographies resemble consummatory response topographies. 相似文献
7.
William Timberlake 《Learning & behavior》1983,11(3):309-320
The present experiments compared rats’ responses to a moving object (a rolling ball bearing) related to either food or water under both Pavlovian and operant contingencies. In Experiment 1, food-restricted rats contacted food-related bearings more frequently and with more complex response patterns than water-restricted rats contacted water-related bearings. Food-related contacts occurred with shorter latency, longer average duration, and increased likelihood of dig, carry, and chew. Experiment 2 revealed that once contact with the bearing had been established, its form persisted despite changes in the type of reward and restriction. In Experiment 3, rats that were simultaneously food and water restricted learned to discriminate between painted and unpainted bearings related to food versus no food, water versus no water, and food versus water. Again, food-related bearings produced more complex, although not more frequent, interactions than did water-related bearings. In none of the experiments did rats lick the ball bearing related to water. The results supported a behavior-system approach, but not the stimulus-substitution or arbitrary-operant accounts of conditioned-response topography. 相似文献
8.
Rats were trained on an interval time-place learning (TPL) task in which the location of food availability depended on the
time since the start of the session. Each of four levers (numbered 1, 2, 3, 4) provided food on an intermittent schedule for
two nonconsecutive 3-min periods. The order in which the levers provided food was 1, 2, 4, 3, 2, 3, 1, 4. This order was consistent
across sessions. Previous research conducted in our lab has shown that when only four “places” are used, rather than the eight
in the present study, rats use a timing strategy to track the location of food. Pizzo and Crystal (2004) recently trained
rats on an interval TPL in which each of eight arms of a radial arm maze provided food. They found evidence suggesting that
rats used both spatial and temporal information. In the present study, in which a revisiting strategy was used (i.e., each
lever provided food on more than one occasion), the rats tracked both the spatial and the temporal availability of food for
the first half of the session. Interestingly, in the second half of the sessions, the rats appeared to be timing the availability
of food even though they did not know where it would occur. That is, the rats knew the temporal, but not the spatial, contingencies
for the second half of the session. It appears that the requirement of revisiting a previously reinforced lever resulted in
rats' no longer being able to solve the spatial aspect of the task. 相似文献
9.
Alba E. Mustaca Fabian Gabelli Mauricio R. Papini Peter Balsam 《Learning & behavior》1991,19(2):125-138
Appetitive contextual conditioning in rats and ringdoves was investigated in six experiments. In Experiment 1, differential contextual training produced greater anticipatory activity in rats in the presence of a context paired with food than it did in rats in the presence of a different context in which food was never presented. Furthermore, the rats showed a preference for the context associated with food when they were given a simultaneous choice test between contexts. In Experiment 2, rats were more active in and preferred a context associated with a variable-time 30-sec (VT30) schedule as opposed to a VT180 schedule. Experiment 3 was a between-subjects replication of the previous experiment. As expected, rats exhibited significantly more anticipatory activity in a context in which food had been presented on a VT30 schedule than they did in a context in which food had been presented on a VT180 schedule. Experiment 4 showed that anticipatory activity was a reflection of context-US associations in ringdoves, and in Experiments 5 and 6, ringdoves also exhibited an inverse relationship between the. amount of anticipatory activity and the length of the interreinforcement interval (IRI). These results reveal a relation between ERI and contextual conditioning opposite from that obtained in studies of aversive conditioning. 相似文献
10.
Rescorla RA 《Learning & behavior》2004,32(4):401-408
Four experiments found the magnitude of spontaneous recovery after extinction to be greater with a shorter interval between
initial conditioning and extinction. Experiments 1 and 2 used a Pavlovian magazine approach procedure with rat subjects, Experiment
3 used an instrumental training procedure with rats, and Experiment 4 used a sign-tracking procedure with pigeons. These results
are not anticipated by many accounts of spontaneous recovery that attribute it to the fading of learning that occurred during
extinction. 相似文献
11.
We conducted three experiments to investigate the associative structure underlying the reinstatement of instrumental performance
after extinction. In each experiment, rats were initially rewarded on two responses with different outcomes. At test, both
responses were extinguished in order to assess the impact of a single noncontingent outcome delivery on response selection.
Experiment 1 found evidence of outcome-selective reinstatement (i.e., more responses were performed on the lever that was
trained with the reinstating outcome than on the other lever). Experiment 2 demonstrated that the outcome’s capacity to reinstate
performance was not affected by a reduction in its motivational value. Experiment 3 found evidence that the reinstating outcome
selectively retrieved the response it signaled rather than the response it followed during training. Together, these findings
are consistent with the view that instrumental reinstatement depends on the discriminative stimulus properties of the reinstating
outcome. 相似文献
12.
In seven experiments, an effect of the intertriai interval (ITI) duration on barpressing by rats was studied. A stimulus signaled a 15-sec variable-interval trial. The first response after the interval elapsed turned the stimulus off and was rewarded with food. Trials were separated by long (about 300 sec) or short (about 10 sec) ITIs. A within-subjects design established that response rate on trials after long ITIs was lower than that after short ITIs (Experiments 1 and 3–7). The effect was not cumulative (the effect of one and five consecutive short ITIs was the same). Response rate after short and long ITIs was the same when a between-subjects design was used (Experiment 2). Response rate was higher after 160-sec ITIs than after 300-sec ITIs, suggesting that the ITI duration at which all longer ITIs are treated the same (i.e., the upper limit) is greater than 160 sec (Experiment 3). When food, the trial stimulus, a novel stimulus, or a familiar stimulus never paired with food, was presented 10 sec before the next trial during some of the long ITIs, response rate on the next trial was similar to that found after 10-sec ITIs (Experiments 4–6). This similarity suggested that these events could mark the start of the ITI. However, the familiar stimulus did so only when it reliably predicted that the next trial would occur after a short interval. The effect of ITI duration on responding was apparently attributable to response latency. Response latency was greater after long ITIs, but once responding began, it was similar after long and short ITIs (Experiment 7). 相似文献
13.
Peter C. Holland 《Learning & behavior》2014,42(4):365-382
Initially neutral conditioned stimuli paired with food often acquire motivating properties, including serving as secondary reinforcers, enhancing instrumental responding in Pavlovian-instrumental transfer procedures, and potentiating food consumption under conditions of food satiation. Interestingly, cues associated with the cancellation of food and food cues may also potentiate food consumption (e.g., Galarce and Holland, 2009), despite their apparent negative correlations with food delivery. In three experiments with rats, we investigated conditions under which potentiation of feeding by such “interruption stimuIi” (ISs) develops, and some aspects of the content of that learning. Although in all three experiments ISs enhanced food consumption beyond control levels, they were found to act as conditioned inhibitors for anticipatory food cup entry (Experiment 1), to serve as conditioned punishers of instrumental responding (Experiment 2), and to suppress instrumental lever press responding in a Pavlovian instrumental transfer procedure (Experiment 3). Furthermore, when given concurrent choice between different foods, an IS enhanced consumption of the food whose interruption it had previously signaled, but when given a choice between performing two instrumental responses, the IS shifted rats’ choice away from the response that had previously yielded the food whose interruption had been signaled by IS (Experiment 3). Thus, the effects of an IS on appetitive responses were opposite to its effects on consummatory responding. Implications for our understanding of learned incentive motivation and the control of overeating are discussed. 相似文献
14.
Three experiments explored responses to molar and local schedule constraints. Thirsty rats pressed a lever for access to a water spout. In Experiment 1, response totals were unaffected by two local schedule characteristics—the variability of the instrumental requirement and the variability of the magnitude of contingent reward. Experiment 2 manipulated the correlation between the instrumental requirement and the magnitude of reward. This correlation did not affect the behavioral price ratio (presses per lick) at a molar level. At a local level, the positive correlation created a lower mean lick price than did the negative correlation. The rats licked more, and licked less efficiently, under the positive correlation than under the negative correlation. Experiment 3 compared two ways of manipulating the molar presses/lick ratio: The instrumental (contingent) series varied the instrumental (contingent) requirement, but held the other requirement constant. As the ratio increased, total leverpresses increased, and total licks decreased linearly; the two series did not differ significantly. At higher lick prices, the rats licked more efficiently and made more extra licks at the spout as it closed. The results help delimit the applicability of molar models of the organism’s response to schedule constraints. 相似文献
15.
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. 相似文献
16.
Anthony Dickinson 《Learning & behavior》1976,4(4):416-420
In Experiment 1, four groups of rats received conditioned suppression training in which a tone was reinforced with shock. If the tone had been previously paired with response-independent food, aversive conditioning was slightly facilitated by comparison to control groups preexposed either to the tone randomly associated with food or to the tone and food unpaired. However, by comparison to a control which was not preexposed to the tone, animals receiving prior pairings of the tone and food showed retarded aversive conditioning. Experiment 2 replicated the facilitation in aversive conditioning after the tone had been paired with food relative to the random control condition and demonstrated that this difference occurred even if the tone and background stimuli continued to be associated with response-independent food during aversive conditioning. This result suggests that pairing a stimulus with an appetitive reinforcer reduces the retardation of aversive conditioning produced by stimulus preexposure. 相似文献
17.
In two experiments, we examined whether or not a loss of control over food availability would interfere with subsequent two-way shuttle-escape learning. Rats that had experienced loss of control over food delivery were impaired in their acquisition of a shuttle-escape response, relative to the response-contingent and the continuous-reinforcement control rats (in Experiments 1 and 2) and to the lack-of-control and home cage control rats (in Experiment 2). Rats that had received noncontingent food delivery without a prior history of control over food exhibited poorer performance than did the home cage control rats. Moreover, loss of control resulted in a larger interference effect than did lack of control, supporting the view that the learning of response-outcome noncontingency is the main determinant of the interference effect. 相似文献
18.
Second-order conditioning (SOC) in pigeons, but not rats, appears to involve an association between the second-order stimulus (S2) and the first-order stimulus (SI). Nairne and Rescorla (1981) suggested it was the use of stimuli from the same modality that promoted an association between S2 and SI in pigeon SOC studies. In support of their hypothesis, they demonstrated that pigeons, like rats, did not form an association between S2 and SI when these stimuli were from different modalities. In this study, we sought to determine whether rats, like pigeons, would associate S2 with SI when these stimuli shared the same modality. Female Lister rats injected with LiCl after consuming .12M saline solution (SI) showed an aversion to a 15% sucrose solution (S2) that was subsequently paired with the saline. This was so regardless of whether S2 and SI had been presented sequentially (Experiment 1) or simultaneously (Experiment 2). Only in Experiment 2, however, did extinction of the aversion to saline diminish the aversion to sucrose; that is, employing stimuli from the same modality was not a sufficient condition, of itself, to allow rats to associate S2 with SI. 相似文献
19.
John Karpicke 《Learning & behavior》1978,6(2):216-224
Three experiments evaluated an alternative to accounts of positive conditioned suppression that stress central (i.e., motivational or emotional) states. This “competing-response” interpretation was tested by analyzing directed movements that develop in rats during a visual or an auditory stimulus (CS) that signals an appetitive reinforcer (US) in a situation where the subject is also emitting an instrumental response for food. In each experiment, positive conditioned suppression (i.e., a reduction in the rate of such instrumental responding during CS presentations) was accompanied by responses directed toward the CS source and/or the US-delivery site. In Experiment 1, a diffuse (auditory) CS signaled a US delivered at some specific place in the chamber and rats approached the US-delivery site during CS. In Experiments 2 and 3, the spatial proximity of a localized visual CS and US-delivery site determined whether CS-directed or US-directed behavior predominated during the CS. The results suggest that the topographies of conditioned responses on any positive conditioned suppression procedure depend upon the spatial arrangements of features that elicit and support these behaviors. They further suggest that the identification of these features and their spatial arrangements is necessary for the analysis of appetitive classical-instrumental interactions. 相似文献
20.
The ability of visual CSs previously paired with flavored substances to substitute for those substances as conditional discriminative cues was examined in two Pavlovian appetitive conditioning experiments using rat subjects. In Experiment 1, a visual stimulus was first paired with the delivery of a sucrose solution. Then the rats were trained in conditional discrimination tasks in which sucrose delivery alone served as a conditional cue signaling whether or not a subsequent tone would be reinforced with food pellets. Subjects rapidly acquired discriminative performance to the tones, especially in a feature-negative condition in which sucrose delivery signaled when the tone would not be reinforced. In a subsequent test in which neither food nor sucrose was delivered, presentation of the visual CS also controlled discriminative performance to subsequently presented tones. Experiment 2 showed the ability of a visual CS to substitute for a flavored substance as a conditional cue to be highly stimulus specific. Experiment 2 also showed that a flavored substance was less effective as a conditional cue when it was made to be expected by preceding it with a previously associated visual signal than when it was made to be surprising by preceding it with a visual stimulus signaling another flavored liquid. These results indicate that CS-evoked representations of events can substitute for those events themselves in the control of previously established conditional discrimination performance. 相似文献