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1.
In these experiments, each rat received two different series of three runs each. The lone group in Experiment 1 received the series 10-0-10 and 10-0-0, where, for example, 10-0-10 means that the rat received three discrete runs (in a runway) that terminated in 10, 0, and 10 pellets, respectively. In Experiment 2, the series were 20-0-0 and 0-0-20 for one group and 20-0-20 and 0-0-0 for another. Of primary concern in both experiments was the rat’s anticipation, as measured by running speed, of 0 pellets on the middle, or second, run of each series. In each experiment, running speed to this 0-pellet event was independent of reinforcement magnitude on the first run of each series and was greater, the greater the reinforcement magnitude on the third run of each series. These results indicate that on the second run of each series the rat was anticipating not merely the 0 pellets associated with that run (intraevent anticipation), but also the reinforcement magnitude associated with the future, third run of each series (interevent anticipation). These results are shown to be consistent with an S-S cognitive view of anticipation and inconsistent with an S-R serial-chaining view of serial learning. 相似文献
2.
Conditioned lick suppression by water-deprived rats was used to elaborate on recent evidence that the attenuated conditioned response elicited by an overshadowed stimulus may be enhanced by extinction of the overshadowing stimulus with which it had been trained in simultaneous compound. Using a modified serial stimulus arrangement in which a light coexisted with the last half of a tone that terminated with footshock, it was found in Experiment 1 that the tone overshadowed the light. Extinction of the tone-shock association resulted in a virtually complete recovery of the response to the overshadowed light. Using this serial overshadowing procedure, the possibility that the strength of a conditioned response to an element trained in compound covaries as a function of the strength of the response to the other element was tested in Experiment 2. Following overshadowing training similar to that of Experiment 1, independent reinforcement of the overshadowed light, that is, associative inflation, was found to have no deleterious effect on the response to the overshadowing tone. This suggests that the effects of postconditioning extinction and inflation of one element do not have symmetrical effects upon responding to the other element. The results of Experiment 2 were replicated in Experiment 3 using a simultaneous compound stimulus as opposed to the serial compound of the previous studies. These results are discussed in terms of various associative and cognitive models of learning and performance. 相似文献
3.
Two experiments were conducted to examine the effects of redundant and relevant visual cues on spatial pattern learning. Rats searched for hidden food items on the tops of poles that formed a square (Experiment 1) or a checkerboard (Experiment 2) pattern. The experimental groups were trained with visual cues that specified the locations of the baited poles. All groups were tested without visual cues so that any overshadowing or facilitation of spatial pattern learning by visual cues could be detected. Spatial choices were controlled by the spatial pattern and by the visual cues in both experiments. However, there was no evidence of overshadowing or facilitation of spatial pattern learning by visual cues in either experiment. The results are consistent with the idea that the representation of the spatial pattern that guides choices is not controlled by the same learning processes as those that produce associations between visual cues and food locations. 相似文献
4.
Philippe Oberling Adam S. Bristol Helena Matute Ralph R. Miller 《Learning & behavior》2000,28(2):172-186
Miller and Matute (1996) showed that blocking is attenuated when the blocked conditioned stimulus (CS) is “biologically significant” (i.e., when the CS has the potential to elicit vigorous responding of any kind). To the extent that blocking is representative of cue competition, this finding suggests that biological significance protects CSs against cue competition effects in general. In the present experiments, we tested this possibility by examining the influence of biological significance of CSs on other examples of cue competition, namely, overshadowing, the relative stimulus validity effect, and the degraded contingency effect in rats. In Experiment 1, we found that intense auditory stimuli induced transient unconditioned lick suppression, thereby indicating that intense sounds were of high inherent biological significance. In Experiment 2A, we found that cues with high inherent biological significance were protected from overshadowing. In Experiment 2B, this finding was extended to cues with high acquired biological significance, which was obtained through prior pairings with a reinforcer of the valence opposite to that used in the overshadowing treatment. In Experiments 3 and 4, we found that cues with high inherent biological significance attenuated the relative validity effect and the degraded contingency effect, respectively. These results lend support to the view that biological significance (inherent and acquired) protects stimuli from cue competition effects, a finding that is problematic for many contemporary theories of learning. 相似文献
5.
In Experiment 1, three groups of rats were trained on one of three serial patterns consisting of different numbers of .045-g food pellets, either the simple strong monotonie pattern 14-7-3-1-0 (Group SM) or one of two complex weak monotonie patterns, 14-5-5-1-0 (Group 5-5) or 14-9-1-1-0 (Group 1-1). Learning to anticipate the terminal 0-pellet element occurred faster in Group 1-1 than in Group SM, which in turn learned faster than Group 5-5. In Experiment 2, Groups SM, 5-5, and 1-1 were trained on the first four elements of the patterns experienced by their Experiment 1 counterparts and then were tested for their ability to extrapolate the series to include the addition of a 0-pellet element in the fifth position. Extrapolation behavior was better in Group 1-1 than in Group SM, which in turn performed better than Group 5-5. The results were shown to be consistent with a memory-discrimination model of serial learning and inconsistent with a rule-learning model based on pattern complexity. 相似文献
6.
This experiment determined if rats could extrapolate a familiar serial sequence of diminishing food quantities by accurately anticipating a novel quantity added to the end of the sequence. In 13 days of training, rats ran in a straight runway to obtain quantities of food pellets presented in sequential order. A strongly monotonic group received repetitions of a formally simple pattern of 14-7-3-1 pellets of food, while weakly monotonic and nonmonotonic groups received formally more complex 14-5-5-1 and 14-3-7-1 patterns, respectively. In subsequent transfer, a 0-pellet quantity was added to each pattern, thus extending pattern length to five elements. Results of the very first pattern repetition containing the added 0-pellet element indicated that rats in the strongly monotonic condition, but not in the others, anticipated the reduced quantity before actually experiencing it. This result supports a cognitive, rule-learning hypothesis for serial learning by rats. 相似文献
7.
Rats, trained in a runway, were asked to anticipate, while running slowly, the last two events in repeating series of .045-g food pellets. The series were either weakly monotonic (14, 5, 5, 1, and then 0 pellets/run) or nonmonotonic (5-5-14-1-0). While the terminal 0-pellet event was better anticipated in the weakly monotonic series, the reverse was the case for the next-to-last 1-pellet event. These findings were expected from a memory-discrimination learning hypothesis of serial learning, which suggests that the memory of one event in a series can be used to signal the next event. However, the better anticipation of the 1-pellet event by the nonmonotonic group was inconsistent with the recently stated rule-encoding position of Hulse (1980). According to that view, difficult series of the sort employed in the present investigation are learned by encoding the rule structure of the series, with events in the series with the simple rule structure (the weakly monotonic series in this investigation) being better anticipated than events in the series with the complex rule structure. 相似文献
8.
Steven J. Haggbloom 《Learning & behavior》1985,13(4):370-374
Four groups of rats (n=6 per group) were trained in a runway on a serial learning task. Groups were treated identically in Phase 1, receiving two daily presentations of a five-element series consisting of decreasing numbers of .045-g food pellets over successive runs, for example, 14-7-3-1-0. All groups learned to anticipate, and run slowly to, the terminal 0-pellet element, behavior that has been attributed to learning of a less-than rule, stimulus-stimulus (S-S) associations, and knowledge of the serial position of items. In Phase 2, subjects were transferred to one of four test series: 20-14-7-3-0,20-7-3-14-0, 20-14-7-3-1-0, or 20-7-14-3-1-0. Anticipation was disrupted on the first two series, which maintained the integrity of serial position information and in the first case the less-than rule, but eliminated the terminal portion of the associative chain. Anticipation was unimpaired by transfer to either of the last two series. These series maintained the integrity of the terminal 3-1-0 portion of the associative chain but presented altered information about serial position, and in the last case also altered the less-than rule. The results, which supported the memory-discrimination model of rat serial learning, are discussed with reference to related transfer experiments in human serial learning. 相似文献
9.
This research focused on the changes in stimulus control that influence an animal’s ability to master a behavioral skill. We assessed stimulus control by (a) predictive environmental cues (panel lights) and (b) practice cues resulting from the subject’s own behavior, as rats learned to complete a left–right lever-press sequence. Following a demonstration of overshadowing by Reid, Nill, and Getz (Behavioural Processes 84: 511–515, 2010), in which stimulus control by the panel lights overshadowed control by practice cues, four additional experiments replicated and assessed this overshadowing effect. In Experiment 1, we discovered a powerful asymmetry: Rats failed to adapt to a lights → reversed-lights transition, but adapted immediately to a reversed-lights → lights transition. Experiment 2 was designed to measure the interactions between these stimulus conditions and practice cues. In Experiment 3, we measured the effect of these stimulus conditions on acquisition rates. Finally, in Experiment 4 an ABA design was used to assess the effects of prior exposure to condition A on B → A transitions, and we found that prior exposure generally reversed the effects observed in B → A transitions presented first or in isolation. We discuss feature-positive bias and spatial S–R compatibility as potential explanations of the observed insensitivity to cues that should be, at face value, highly predictive of food during the acquisition of a behavioral skill. Perfectly predictive cues in behavior chains do not always guide behavior. 相似文献
10.
Edward S. Redhead Derek A. Hamilton Matthew O. Parker Wai Chan Craig Allison 《Learning & behavior》2013,41(2):179-191
In three experiments, we examined whether overshadowing of geometric cues by a discrete landmark (beacon) is due to the relative saliences of the cues. Using a virtual water maze task, human participants were required to locate a platform marked by a beacon in a distinctively shaped pool. In Experiment 1, the beacon overshadowed geometric cues in a trapezium, but not in an isosceles triangle. The longer escape latencies during acquisition in the trapezium control group with no beacon suggest that the geometric cues in the trapezium were less salient than those in the triangle. In Experiment 2, we evaluated whether generalization decrement, caused by the removal of the beacon at test, could account for overshadowing. An additional beacon was placed in an alternative corner. For the control groups, the beacons were identical; for the overshadow groups, they were visually unique. Overshadowing was again found in the trapezium. In Experiment 3, we tested whether the absence of overshadowing in the triangle was due to the geometric cues being more salient than the beacon. Following training, the beacon was relocated to a different corner. Participants approached the beacon rather than the trained platform corner, suggesting that the beacon was more salient. These results suggest that associative processes do not fully explain cue competition in the spatial domain. 相似文献
11.
In each of two investigations, rats ran in a runway to obtain varying quantities of food pellets presented in a fixed order, such as 20-0-20. The major finding was that rats ran faster on a 0-pellet trial if that trial was followed shortly by a 20-pellet trial (e.g., 20-0-20 series) than if it was not (e.g., 20-0 series). This finding was obtained both within groups (Experiment 1) and between groups (Experiment 2), and suggested that the memory of 20 pellets arising from the first trial of the 20-0-20 series was retrieved not only on the second trial of the series, thereby signaling 0 pellets, but on the third trial as well, thereby also signaling 20 pellets. Retrieving the memory of 20 pellets on Trial 3 of the 20-0-20 series apparently resulted in that memory’s elevating speed on Trial 2 of that series. 相似文献
12.
Three experiments examined human processing of stimuli as predictors and causes. In Experiments 1A and 1B, two serial events
that both preceded a third were assessed as predictors and as causes of the third event. Instructions successfully provided
scenarios in which one of the serial (target) stimuli was viewed as a strong predictor but as a weak cause of the third event.
In Experiment 2, participants’ preexperimental knowledge was drawn upon in such a way that two simultaneous antecedent events
were processed as predictors or causes, which strongly influenced the occurrence of overshadowing between the antecedent events.
Although a tendency toward overshadowing was found between predictors, reliable overshadowing was observed only between causes,
and then only when the test question was causal. Together with other evidence in the human learning literature, the present
results suggest that predictive and causal learning obey similar laws, but there is a greater susceptibility to cue competition
in causal than predictive attribution. 相似文献
13.
Carla J Posnansky 《Contemporary educational psychology》1976,1(3):247-256
The present studies examined the effectiveness of explicit and implicit Forget cues for enhancing memory of to-be-remembered items within a directed forgetting paradigm. Such a paradigm may be viewed as a laboratory analogue to a classroom testing situation where students read through an examination before beginning in order to cue themselves as to which information is important to remember. Subjects were third- and seventh-grade children. Evidence was provided that directed forgetting processes were operative at the time of recall so that memory enhancement did not merely reflect differential rehearsal of the to-be-remembered items during study. When easy partitioning of items into Remember and Forget sets was possible, subjects as young as third graders could benefit from postpresentation Forget cues. The data suggest that postpresentation Forget cues permit a selective search during recall and a consequent reduction in interference from to-be-forgotten items. Applications of these findings to a classroom testing situation were discussed. 相似文献
14.
In two experiments, rats were presented with a taste conditioned stimulus (CS) alone, an odor CS alone, or an odor-taste compound followed by lithium chloride injection. When tested 1 day following conditioning, there was evidence that the odor cue overshadowed conditioning to the taste; however, there was no indication of overshadowing following a longer (21-day) retention interval, despite undiminished strength of the aversion in animals conditioned with only the single element (taste). The overshadowing observed at the 1-day retention interval was not reciprocal. Rats conditioned with the odor CS alone or with the compound CS expressed odor aversions of comparable strength—that is, no overshadowing. However, in contrast to the taste aversion, overshadowing of conditioning to the odor by taste was evident following a 21-day retention interval. Rather than reflecting a failure of the overshadowed stimulus to acquire associative strength, these data suggest that overshadowing may be expressed, or not expressed, as a result of changes in the relative retrievability of learned associations over time. 相似文献
15.
When rats receive a sequence of rewards of different magnitudes for traversing a runway, they learn to “track” the sequence, showing anticipation of the forthcoming reward by appropriate running speed. There is disagreement as to whether this behavior depends on rats’ encoding and recalling a complete sequence of foregoing hedonic events or just the immediately preceding one. The present experiments showed that rats can remember more hedonic events than the most recent one. In Experiment 1, when exposed concurrently to the sequences 10-1-0 (pellets) and 0-1-10, they were faster on Run 3 of the increasing than of the decreasing sequence, a discrimination which cannot be made on the basis of the preceding (1-pellet) reward alone. Experiment 2 showed that this behavior reflects genuine anticipation of the Run 3 reward, not simultaneous contrast or other simple aftereffects of Runs 1 and 2. It is argued, however, that these results, together with related findings by Capaldi and Verry (1981), show merely that rats can recall a hedonic event other than the most recent one, not that a sequence of such events is fully recalled in order. 相似文献
16.
The effects of signaled reward were examined using DRL and DRH schedules of reinforcement. In each case, one group of rats received a brief cue between the reinforced response and the reward, and a second group received brief cues at random times. With the DRL schedule (Experiment 1), signaled reward decreased response rate, increased response efficiency (number of responses per reinforcer), and increased resistence to satiation relative to the control group. With the DRH schedule (Experiment 2), signaled reward increased response rate, efficiency, and resistance to satiation. These results refute an overshadowing explanation of the effects of signaled reward and suggest that food-correlated cues enhance learning of the reinforcement contingencies. 相似文献
17.
Two experiments with rats tested independent predictions from cognitive theories of serial pattern learning. The animals learned to anticipate, as measured by running times in a straight alley, different quantities of food pellets organized into formally defined, five-element serial patterns. In Experiment 1, for some animals the patterns were all formally structured according to a monotonic “less than” relationship in which any quantity was always less than its predecessor. For others, no consistent formal rule was applied. Results of a transfer test with a new pattern showed positive transfer if the formal structure of the new pattern was identical to that used initially, but negative transfer if the new pattern was formally different. In Experiment 2, two groups learned the monotonic patterns 18-10-6-3-1 or 18-10-6-3-0 food pellets, while two others learned the nonmonotonic patterns 18-3-6-10-1 or 10-3-6-10-0 food pellets. We asked if the difference in value of the terminal element, 1 or 0 food pellets, would affect the facility with which the patterns were learned. The results showed that learning rate and the qualitative response to the elements of the monotonie and nonmonotonic patterns were independent of the value of the terminal element. Both experiments lend additional support to the utility of using cognitive models of human serial-pattern learning for an analysis of the sequential behavior of nonhuman animals. 相似文献
18.
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
19.
Todd R. Schachtman Wesley J. Kasprow Robert C. Meyer Mark J. Bourne Julie A. Hart 《Learning & behavior》1992,20(3):207-218
Using a conditioned taste aversion preparation overshadowing of flavor-illness association was produced through the presentation of a second flavor during the interval between the first flavor and illness. The modulatory effects of extinguishing the association between the second (over-shadowing) flavor and illness on conditioned responding to the target flavor was investigated. In Experiment 1, we found that, following one-trial overshadowing, extinction of the overshadowing flavor had no effect on conditioned responding to the target flavor. In Experiment 2, we found a similar absence of an effect of extinction of the overshadowing stimulus in a multitrial over-shadowing paradigm. Experiment 3 confirmed the results of Experiments 1 and 2 using conditioning parameters that were designed to weaken the association between the overshadowed flavor and illness. In Experiments 4 and 5, we used simultaneous presentation of the flavors during conditioning and obtained a weakened aversion to the overshadowed flavor when the overshadowing CS was extinguished. These findings are inconsistent with previous observations in conditioned fear preparations that suggest that extinction of the association between the overshadowing stimulus and the unconditioned stimulus attenuates overshadowing. Possible reasons for the discrepant results are discussed. 相似文献
20.
In four experiments using rat subjects, we investigated the effects of presenting a novel flavor cue at the time of pairing an environmental context with illness. In each experiment, the subjects were allowed to spend time in a distinctive cage before receiving an injection of LiCl. For some, plain water was made available on these conditioning trials; for others, a novel taste (HCl) was presented. We measured the strength of the context aversion by assessing the ability of the contextual cues to block the acquisition of an aversion to sucrose in a further phase of training. We found that initial training with HCl present made the context less effective as a blocking cue and concluded that the HCl had overshadowed learning about the context. We suggest that this blocking procedure provides a more accurate assessment of contextual aversion than does the consumption test that has more usually been used and that taste-context overshadowing may be a more robust phenomenon than has thus far been thought. 相似文献