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1.
The associative learning effect called blocking has previously been found in many cue-competition paradigms where all cues
are of equal salience. Previous research by Hall, Mackintosh, Goodall, and dal Martello (1977) found that, in animals, salient
cues were less likely to be blocked. Crucially, they also found that when the to-be-blocked cue was highly salient, the blocking
cue would lose some control over responding. The present article extends these findings to humans and suggests that shifts
in attention can explain the apparent loss of control by the previously learned cue. A connectionist model that implements
attentional learning is shown to fit the main trends in the data. Model comparisons suggest that mere forgetting, implemented
as weight decay, cannot explain the results. 相似文献
2.
Dickinson and Burke (1996) proposed a modified version of Wagner’s (1981) SOP associative theory to explain retrospective
revaluation of human causal judgments. In this modified SOP (MSOP), excitatory learning occurs when cue and outcome representations
are either both directly activated or both associatively activated. By contrast, inhibitory learning occurs when one representation
is directly activated while the other is associatively activated. Finite node simulations of MSOP yielded simple acquisition,
overshadowing, blocking, and inhibitory learning under forward contingencies. Importantly, retrospective revaluation was predicted
in the form of unovershadowing and backward inhibitory learning. However, MSOP did not yield backward blocking. These predictions
are evaluated against the relevant empirical evidence and contrasted with the predictions of other associative theories that
have been applied to retrospective revaluation of human causal and predictive learning. 相似文献
3.
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
4.
In four trace-conditioning experiments with rats, the influence on the blocking of differences between the blocking cue-unconditioned
stimulus (US) and the blocked cue-US trace intervals was explored. Experiment 1 demonstrated blocking despite the blocked
cue’s having a shorter trace interval than the blocking cue in both elemental (Phase 1) and compound (Phase 2) training. In
Experiment 2, blocking was attenuated when the blocked cue had a longer trace interval than did the blocking cue in both elemental
and compound training. In Experiments 3 and 4, the trace intervals of the two cues during compound training were matched (i.e.,
unlike in Experiments 1 and 2, neither had temporal priority). Blocking was attenuated when the blocking cue trace interval
in the elemental phase was shorter (Experiment 3) or longer (Experiment 4) than the compound cue trace during compound training.
The findings indicate that subjects encode interstimulus intervals, and they further suggest that cue competition is greatest
when the competing cues have the same temporal information as the US. 相似文献
5.
The dominant theoretical approach to causal learning postulates the acquisition of associative weights between cues and outcomes.
This reduction of causal induction to associative learning implies that learners are insensitive to important characteristics
of causality, such as the inherent directionality between causes and effects. An ongoing debate centers on the question of
whether causal learning is sensitive to causal directionality (as is postulated by causal-model theory) or whether it neglects
this important feature of the physical world (as implied by associationist theories). Three experiments using different cue
competition paradigms are reported that demonstrate the competence of human learners to differentiate between predictive and
diagnostic learning. However, the experiments also show that this competence displays itself best in learning situations with
few processing demands and with convincingly conveyed causal structures. The study provides evidence for the necessity to
distinguish between competence and performance in causal learning. 相似文献
6.
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
7.
Pigeons were trained in two experiments with negative patterning discriminations that were accompanied by an irrelevant cue.
For Experiment 1, the discriminations were of the form AX+ BX+ ABX–, where A and B were relevant, X was irrelevant, and +
or – indicate whether or not reinforcement was delivered. The discriminations for Experiment 2 were of the form A+ B+ AX+
BX+ ABX–. A subsequent test phase in both experiments revealed that the associability of A and B, and hence the attention
paid to these stimuli, was less than the associability of X. The results are explained with a modified version of a configural
theory of associative learning. 相似文献
8.
Two experiments investigated extinction and blocking of a conditioned inhibitor in a human contingency learning task. Lotz
and Lachnit (2009) and Melchers, Wolff, and Lachnit (2006) reported extinction of inhibition only when participants experienced
outcome levels lower than those used in training. In Experiment 1, which used more neutral instructions than the previously
mentioned studies, we found that extinction of inhibition occurred, whether or not participants experienced lower outcome
levels. In Experiment 2, we applied this outcome manipulation to blocking of a conditioned inhibitor. We found blocking of
inhibition both when participants had experience with lower outcomes and when they did not. The results of our two experiments
are consistent with Rescorla and Wagner’s (1972) associative model, and inconsistent with an inferential account of causal
learning (De Houwer, Beckers, & Vandorpe, 2005). 相似文献
9.
Are humans unique in their ability to interpret exogenous events as causes? We addressed this question by observing the behavior of rats for indications of causal learning. Within an operant motor–sensory preconditioning paradigm, associative surgical techniques revealed that rats attempted to control an outcome (i.e., a potential effect) by manipulating a potential exogenous cause (i.e., an intervention). Rats were able to generate an innocuous auditory stimulus. This stimulus was then paired with an aversive stimulus. The animals subsequently avoided potential generation of the predictive cue, but not if the aversive stimulus was subsequently devalued or the predictive cue was extinguished (Exp. 1). In Experiment 2, we demonstrated that the aversive stimulus we used was in fact aversive, that it was subject to devaluation, that the cue–aversive stimulus pairings did make the cue a conditioned stimulus, and that the cue was subject to extinction. In Experiments 3 and 4, we established that the decrease in leverpressing observed in Experiment 1 was goal-directed instrumental behavior rather than purely a product of Pavlovian conditioning. To the extent that interventions suggest causal reasoning, it appears that causal reasoning can be based on associations between contiguous exogenous events. Thus, contiguity appears capable of establishing causal relationships between exogenous events. Our results challenge the widely held view that causal learning is uniquely human, and suggest that causal learning is explicable in an associative framework. 相似文献
10.
Additivity-related assumptions have been proven to modulate blocking in human causal learning. Typically, these assumptions are manipulated by means of pretraining phases (including exposure to different outcome magnitudes), or through explicit instructions. In two experiments, we used a different approach that involved neither pretraining nor instructional manipulations. Instead, we manipulated the causal structure in which the cues were embedded, thereby appealing directly to the participants’ prior knowledge about causal relations and how causes would add up to yield stronger outcomes. Specifically, in our “different-system” condition, the participants should assume that the outcomes would add up, whereas in our “same-system” condition, a ceiling effect would prevent such an assumption. Consistent with our predictions, Experiment 1 showed that, when two cues from separate causal systems were combined, the participants did expect a stronger outcome on compound trials, and blocking was found, whereas when the cues belonged to the same causal system, the participants did not expect a stronger outcome on compound trials, and blocking was not observed. The results were partially replicated in Experiment 2, in which this pattern was found when the cues were tested for the second time. This evidence supports the claim that prior knowledge about the nature of causal relations can affect human causal learning. In addition, the fact that we did not manipulate causal assumptions through pretraining renders the results hard to account for with associative theories of learning. 相似文献
11.
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
12.
The blocking phenomenon was investigated in the sexual response system of male Japanese quail. Access to a live female quail served as the unconditioned stimulus (US). The same audiovisual cue served as the pretrained stimulus in all of the experiments. Following asymptotic conditioning of the audiovisual cue, a second conditioned stimulus (CS2) was added. In Experiment 1, CS2 was a rectangular wood block that had little or no resemblance to a female quail and could not support copulatory behavior. In Experiment 2, CS2 was a terrycloth object that had no quail parts but could support copulatory behavior, and, in Experiment 3, CS2 was a terrycloth object that had a taxidermically prepared head of a female quail added. The terrycloth-only object supported more rapid conditioning than did the wood block, but the blocking effect was obtained with both kinds of stimuli. Approach responding to the terrycloth + head object required pairing it with copulatory opportunity, and the terrycloth + head object supported at least as rapid conditioning as did the terrycloth-only object. However, responding to the terrycloth + head object was not blocked by the pretrained audiovisual cue. These results indicate that the blocking effect occurs in sexual conditioning even with stimulus objects that can support copulation. However, the addition of species-typical head cues to an object makes that object such a powerful stimulus that conditioned approach responding to it cannot be blocked by a previously conditioned arbitrary audiovisual cue. 相似文献
13.
Cognitive map theory assumes that novel environmental information is automatically incorporated into existing cognitive maps
as a function of exploration. Reports of blocking in place learning cast doubt on this claim. In these studies, subjects were
first trained to find a place, using a set of landmarks (Set A). Then novel landmarks (Set B) were added for additional trials.
Subsequent removal of the Set A landmarks showed that the novel landmarks alone were insufficient for successful navigation.
We investigated whether instructing human subjects to explore the environment can moderate blocking. First, we demonstrated
that blocking is absent in a computer implementation of the Morris water maze (MWM) in which subjects are instructed to explore.
We then studied why others found blocking in a different MWM implementation, in which the task instructions did not suggest
exploration. In experiments that faithfully replicated this MWM variant, we found that subjects did not acquire cognitive
maps and that blocking was attenuated when instructions were provided that encouraged exploration. Together, these findings
indicate that blocking in human place learning may reflect a performance deficit, not a learning deficit, and that instructions
can moderate blocking. Our results thus support the automatic update assumption of cognitive map theory. 相似文献
14.
Rats were trained in a triangular-shaped pool to find a hidden platform that maintained a constant relationship with two sources
of information, an individual landmark and one part of the pool with a distinctive shape. In Experiment 1, shape learning overshadowed landmark learning but landmark learning did not overshadow shape learning in males, while landmark
learning overshadowed shape learning but shape learning did not overshadow landmark learning in females. In Experiment 2,
rats were pretrained either with the single landmark relevant or with the shape relevant, in the absence of the alternative
cue. Final test trials, without the platform, revealed reciprocal blocking only in females; in males, shape learning blocked
landmark learning, but not viceversa (Experiment 2a). In Experiment 2b, male rats received a longer pretraining with the single landmark relevant, and now landmark learning blocked shape learning.
The results thus confirm the claim that males and females partially use different types of spatial information when solving
spatial tasks. These results also agree with the suggestion that shape learning interacts with landmark learning in much the
same way as does learning about any pair of stimuli in a Pavlovian conditioning experiment. 相似文献
15.
In three experiments, we used the allergist task to examine the role of error correction mechanisms in the acquisition and extinction of causal judgments in people. Consistent with existing human and animal studies, acquisition of causal judgments was influenced by the discrepancy between the allergenic outcome and that predicted by all of the cues present on a trial (the "common error" term). However, in the present experiments, we failed to detect any evidence for the use of a common error term in extinction learning: Judgments of the allergenic properties of a cue were unaffected by the predictive value of the other cues present on a trial. This asymmetry in the use of a common error term in acquisition and extinction learning is inconsistent with previous animal studies and also with most models of associative learning. However, approaches that allow learning to be specific to a particular arrangement of elemental cues (context specific and state based) offer some explanation of the observed asymmetry. 相似文献
16.
Thorwart and Lachnit (2009) found reliable symmetrical decrements in two generalization tasks: Removing an already trained
component from a compound did not result in larger decrements than adding a new one did. In two contingency learning experiments,
we investigated first whether time pressure during stimulus processing, as well as the degree of perceptual grouping, was
effective in controlling the symmetry of the decrements (Experiment 1); and second, whether the symmetry was affected by the
causal versus predictive nature of the relationship between the cue and the outcome (Experiment 2). The experiments generated
unexpected results, since both revealed asymmetrical decrements independent of the manipulations introduced. They therefore
demonstrate that more research is needed in order to understand the variables influencing stimulus representation in human
associative learning. 相似文献
17.
It is said that “absence makes the heart grow fonder.” But, when and why does an absent event become salient to the heart or to the brain? An absent event may become salient when its nonoccurrence is surprising. Van Hamme and Wasserman (1994) found that a nonpresented but expected stimulus can actually change its associative status—and in the opposite direction from a presented stimulus. Associative models like that of Rescorla and Wagner (1972) focus only on presented cues; so, they cannot explain this result. However, absent cues can be permitted to change their value by assigning different learning parameters to present and absent cues. Van Hamme and Wasserman revised the Rescorla-Wagner model so that the α parameter is positive for present cues, but negative for absent cues; now, changes in the associative strength of absent cues move in the opposite direction as presented ones. This revised Rescorla-Wagner model can thus explain such otherwise vexing empirical findings as backward blocking, recovery from overshadowing, and backward conditioned inhibition. Moreover, the revised model predicts new effects. For example, explicit information about the absence of nonpresented cues should increase their salience (that is, their negative α value should be larger), leading to stronger associative changes than when no explicit mention is made of cue absence. Support for this prediction is detailed in a new causal judgment experiment in which participants rated the effectiveness of different foods’ triggering a patient’s allergic reaction. Overall, these and other findings encourage us to view human causal learning from an associative perspective. 相似文献
18.
Several experiments on human causal reasoning have demonstrated “discounting”-that the presence of a strong alternative cause
may decrease the perceived efficacy of a moderate target cause. Some, but not all, of these effects have been shown to be
attributable to subjects’ use of conditional rather than unconditional contingencies (i.e., subjects control for alternative
causes). We review experimental results that do not conform to the conditionalizing contingency account of causal judgment.
In four experiments, we demonstrate that there is “nonnormative discounting” above what is accounted for by conditionalization,
that discounting may depend on the nature of the question put to the subjects, and that discounting can be affected by motivation.
We conclude that because nonnormative discounting occurs for summary presentations as well as trial-by-trial presentations
of information and because nonnormative discounting depends on motivation, it is not a necessary result of cue competition
during the contingency learning process. 相似文献
19.
In three experiments, we show that people respond differently when they make predictions as opposed to when they are asked
to estimate the causal or the predictive value of cues: Their response to each of those three questions is based on different
sets of information. More specifically, we show that prediction judgments depend on the probability of the outcome given the
cue, whereas causal and predictivevalue judgments depend on thecue-outcome contingency. Although these results might seem problematic for most associative models in their present form, they can be explained by
explicitly assuming the existence of postacquisition processes that modulate participants’ responses in a flexible way. 相似文献
20.
In three experiments, we investigated the contextual control of attention in human discrimination learning. In each experiment, participants initially received discrimination training in which the cues from Dimension A were relevant in Context 1 but irrelevant in Context 2, whereas the cues from Dimension B were irrelevant in Context 1 but relevant in Context 2. In Experiment 1, the same cues from each dimension were used in Contexts 1 and 2, whereas in Experiments 2 and 3, the cues from each dimension were changed across contexts. In each experiment, participants were subsequently shifted to a transfer discrimination involving novel cues from either dimension, to assess the contextual control of attention. In Experiment 1, measures of eye gaze during the transfer discrimination revealed that Dimension A received more attention than Dimension B in Context 1, whereas the reverse occurred in Context 2. Corresponding results indicating the contextual control of attention were found in Experiments 2 and 3, in which we used the speed of learning (associability) as an indirect marker of learned attentional changes. Implications of our results for current theories of learning and attention are discussed. 相似文献