共查询到20条相似文献，搜索用时 765 毫秒
1.
Anthony S. Rauhut Janice E. Mcphee Norma T. Dipietro John J. B. Ayres 《Learning & behavior》2000,28(1):92-108
In each of two experiments, we studied Pavlovian fear conditioning (as assessed by barpress conditioned suppression) in 32 albino rats. Following a two-stage cue-competition procedure (A+ then AX+), we subjected the competing cue (A) to conditioned inhibition training (B+, BA?) before testing the target cue (X). Conditioned inhibition training was designed to weaken the putative A-unconditioned stimulus (US) association, perhaps changing it to an A-no-US association. Performance-deficit theories of cue competition, such as comparator theory and retrieval-interference theory, predict that such procedures should weaken cue competition, causing Conditioned Stimulus X (CS X) to evoke strong responding. The same prediction can be deduced from recent acquisition-focused models (Dickinson &; Burke, 1996; Van Hamme &; Wasserman, 1994). In opposition to this prediction, however, we found in both experiments that conditioned inhibition training had no detectable effect on cue competition even though it successfully abolished conditioned responding to CS A. In Experiment 2, moreover, we found evidence against the hypothesis that the weak response to CS X was due to generalization decrement rather than to cue competition. Results favor early learning-deficit theories of cue competition over performance-deficit theories and over the recent acquisition-focused models. 相似文献
2.
C. H. Bennett V. L. Scahill D. P. Griffiths N. J. Mackintosh 《Learning & behavior》1999,27(3):333-345
Preexposure to two compound flavors (AX and BX) typically enhances their discriminability: An aversion conditioned to AX will generalize less to BX, especially if the preexposure regime has involved alternated presentations of AX and BX rather than presenting all AX trials before BX trials (or vice versa). One possible explanation of this finding is that alternating preexposure establishes inhibitory associations between the two unique features A and B, thus counteracting the generalization produced by excitatory associations between X and A and between X and B, which might result in either the retrieval of B on a conditioning trial to AX, or the retrieval of A on a test trial to BX. Three experiments on flavor aversion conditioning in rats tested these predictions. Experiment 1 suggested that the more important of these excitatory associations was that which allowed X to retrieve A on the test trial to BX. Experiment 2 suggested that the more important inhibitory association was that which allowed B to inhibit the representation of A on this test trial. Experiment 3 provided direct evidence of the role of this inhibitory B⊣A association. 相似文献
3.
Using a light or backshock as the reinforced CS (A) and a tone or backshock as the conditioned inhibitor (X), rabbits experienced conditioned inhibition training in an A+/AX? paradigm. Following training, the amplitude of the unconditioned nictitating membrane response elicited by a mild (.5-mA) paraorbital shock was measured in the presence of X and AX and expressed as a percentage of the amplitude of the UR to the shock presented alone. In Experiment 1, the effect of X and AX on UR amplitude for conditioned inhibition animals was compared with that of control animals treated to a variety of pretest procedures. In general, UR amplitude in the presence of X exceeded that observed to the US presented alone. There was no consistent difference between the experimental and control groups. In Experiments 2–5, A test trials were added as an alternative reference point. Again, UR amplitude increased rather than decreased UR amplitude. In addition, X as a conditioned inhibitor enhanced the facilitating effect of A on UR amplitude in four out of five experiments. These findings have implications for theories of the “locus of action” of conditioned inhibitors. 相似文献
4.
Michael J. Detke 《Learning & behavior》1991,19(4):345-354
Extinction of inhibition was examined in three pigeon autoshaping experiments. In Experiment 1, a sequential conditioned inhibitor (CI) lost inhibitory power after extinction trials. In Experiment 2, this loss of inhibition was replicated, and the effect was general to both the original target and a transfer target that was separately trained in an inhibition design. In Experiment 3, two CIs were trained simultaneously and two sequentially, and one of each was extinguished; all were tested simultaneously and sequentially. The results show that sequential testing is a necessary component for observing loss of inhibition. This is not consistent with an actual loss of inhibitory associations. It is suggested that the extinction trials either decrease processing of the CI, or extinguish its excitatory properties, to which some of the inhibition may be conditioned. 相似文献
5.
Four experiments examined generalization of latent inhibition (LI) as a function of the length of preexposure in a conditioned
taste aversion procedure with rats. Experiment 1 showed that one or four nonreinforced presentations of a flavor compound (BX) retarded subsequent conditioning to another
compound (AX). However, after eight presentations of BX, conditioning to AX occurred at the same rate as with no preexposure.
These results indicate that generalization of LI decreased as the length of preexposure to BX increased. Experiment 2 replicated this effect of reducing generalization, as well as demonstrating that LI actually increased as the length of preexposure
to AX increased. Experiment 3 extended the generality of the effect to a procedure in which both BX and AX were preexposed. Experiment 4 demonstrated a similar reducing-generalization effect when generalization of LI from BX to X was assessed. All of these data
are consistent with the notion that prolonged preexposure to BX enhances its discriminability. Different learning mechanisms
that might be responsible for this perceptual learning effect are discussed. 相似文献
6.
Three experiments examined inhibitory learning in rats, using Pavlovian and differential inhibitory eyeblink conditioning
procedures. Experiment 1 was designed to compare summation and retardation effects following Pavlovian conditioned inhibition
(A1/XA) or differential inhibition (A1/X) training using auditory and visual conditioned stimuli (CSs). After ten 100-trial
sessions of training, both Pavlovian conditioned inhibition and differential inhibition produced a retardation effect. However,
a summation effect was obtained only for rats given Pavlovian conditioned inhibition training. Experiment 2 showed that increasing
differential inhibition training to twenty 100-trial sessions produced summation and retardation effects. In Experiment 3,
rats were trained with either ten or twenty 100-trial sessions of intramodal inhibitory training with two tone CSs (2 kHz
vs. 8 kHz). Summation and retardation effects were obtained after only 20 sessions of differential conditioning. The findings
indicate that extensive training is needed to establish conditioned inhibition with intermodal or intramodal differential
conditioning. 相似文献
7.
In Experiments 1 and 2, rats were exposed to two compound flavors, AX and BX, containing one flavor in common (X). Following this exposure phase, an aversion was conditioned to A in the experimental group by pairing its consumption with an injection of lithium, while a control group drank A without being poisoned. The effect of this treatment was to establish B as a conditioned inhibitor. In Experiment 1, experimental animals were slower than controls to condition an aversion to B when its consumption was paired with lithium (a retardation test of conditioned inhibition). In Experiment 2, B alleviated the suppression of intake of another flavor previously paired with lithium (a summation test). Experiments 3 and 4 established that these effects depended upon prolonged prior exposure to AX and BX. 相似文献
8.
Overshadowing and associability change: Examining the contribution of differential stimulus exposure
In two appetitive conditioning experiments with rats, we investigated the mechanisms responsible for demonstrations of the superior associability of overshadowed conditioned stimuli (CSs) relative to control CSs. In Experiment 1, we investigated whether previous demonstrations were a consequence of differences in the relationship between the CSs and the unconditioned stimulus (US) or of differences in the conditions of exposure to the CSs. Rats received trials with X, Y, and an AB compound, but no delivery of the US (X–, Y–, AB–). A subsequent AY–, AX+, BY + test discrimination revealed that the AY/BY component of the discrimination was solved more readily than the AY/AX component—suggesting the contribution of an exposure effect. In Experiment 2, we better equated the conditions of exposure between A and Y by using AB+, XY+, X– training in Stage 1. In Stage 2, instrumental responses were rewarded during an AY compound. A final test revealed that Y took better control of instrumental responding than did A. The results of these experiments are discussed in terms of classical and contemporary theories of learning and attention. 相似文献
9.
Four experiments explored various applications of the retardation test of inhibition following discriminative autoshaping. In all studies, discriminative autoshaping consisted of food-reinforced presentations of a green key-light CS+ and nonreinforced presentations of a vertical white line on a green background CS?. In Experiment 1, the inhibitory properties of the vertical Une CS? were assessed by comparing the acquisition of keypecking to the now-reinforced vertical line CS in groups previously receiving discriminative autoshaping (as above), discriminative autoshaping with a red key CS?, and nondiscriminative autoshaping. The results indicated that the former CS? was retarded in being transformed into a CS+. In Experiment 2, the discriminative autoshaping procedure was followed by testing for acquisition with independent groups receiving one of four different CSs differentiated by line orientation. The results indicated that the orientation attribute of the CS? was inhibitory, in that a between-subjects resistance-to-reinforcement gradient of inhibition was obtained. In Experiment 3, discriminative autoshaping was followed by a within-subjects resistance-to-reinforcement generalization test based on line orientation, which failed to yield an orderly gradient. The implementation of a DRO contingency in the within-subjects test (Experiment 4) was ineffective in generating an incremental gradient. Implications for inhibitory assessment methodology are discussed. 相似文献
10.
Robert A. Rescorla 《Learning & behavior》1999,27(2):140-151
In four experiments, rat subjects were used in appetitive Pavlovian magazine-approach and instrumental conditioning procedures. Experiments 1 and 2 found successful blocking of the Pavlovian conditioning of X when it was reinforced in an AX compound after prior conditioning of A. This occurred whether the outcome following AX was the same as or qualitatively different from what followed A. Experiment 3 repeated those findings but also used a transfer procedure to identify the individual associations between X and outcomes. Stimulus X developed an association with the outcome following AX when that outcome differed from that following A alone but not when it was the same as that following A alone. Experiment 4 repeated that pattern of observations for the case of an X that was an instrumental discriminative stimulus. These results suggest that different associative structures may result from a qualitatively changed and unchanged outcome in a blocking experiment. The results are related to comparable findings for the case of overexpectation. 相似文献
11.
In three experiments, rats were given concurrent exposure to a compound flavor (AX) and to one of the elements of the compound
(X). The perceptual effectiveness of A was then assessed by a test involving generalization of a conditioned aversion. Comparison
was made with a preexposure procedure in which the compound and the common element were presented on separate trials, either
in alternation or in separate blocks of trials. The effectiveness of the unique cue was less after blocked preexposure than
after either of the other procedures; concurrent preexposure did not produce a greater effect than did alternating preexposure.
These results challenge the suggestion that concurrent preexposure engages a special comparison process that will facilitate
this form of perceptual learning. 相似文献
12.
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
13.
Philipp J. Kraemer Christopher K. Randall Timothy J. Carbary 《Learning & behavior》1991,19(2):139-145
A conditioned emotional response procedure was used to study the interactive effects of stimulus preexposure and retention interval in rats. In Experiment 1, the subjects were conditioned by presenting a light CS paired with mild footshock as the US. Half of the subjects were given nonreinforced preexposure to the CS, and the others were not. Separate preexposed and nonpreexposed groups were then tested 1,7, or 21 days after conditioning. Suppression of ongoing activity was used to assess the degree of conditioned fear. Latent inhibition was found at the 1-day retention interval; the preexposed subjects displayed less conditioned fear than did the nonpreexposed subjects. In contrast, equally strong conditioned fear was expressed by the preexposed and the nonpreexposed groups tested after the 7- and the 21-day retention intervals. These results indicate a release from latent inhibition similar to that obtained with conditioned taste aversions (Kraemer & Roberts, 1984). The results of Experiment 2 suggest that retention-interval-induced increases in sensitization, pseudoconditioning, or neophobia cannot account for the release from latent inhibition effect obtained in Experiment 1. The implications of these findings for a retrievaloriented view of latent inhibition are discussed. 相似文献
14.
Three experiments demonstrated Pavlovian appetitive discrimination learning in the marine mollusc,Aplysia californica. In each experiment, subjects were exposed to two conditioned stimuli; one stimulus (CS+) was paired with food presentations and the other stimulus (CS?) was never followed by food. In Experiments 1 and 3 different chemosensory stimuli were used, and in Experiment 2 different tactile stimuli were used. For both types of conditioned stimuli, bite responses occurred significantly more often to the CS+ than to the CS?. Experiment 2 also showed thatAplysia could learn a reversal of this discrimination. Experiment 3 showed that nonreinforced presentations of CS+ resulted in a decline in the frequency of conditioned biting. The implications of these results for neurobiological analyses of learning are discussed. 相似文献
15.
Two conditioned lick suppression experiments with rats used feature-negative training (A-footshock trials intermixed with
nonreinforced XA presentations) to analyze the role of the number of XA compound presentations and the temporal relationship
of the elements within the compound (simultaneous or serial) as determinants of the resulting behavioral control. Second-order
conditioning (i.e., excitatory behavioral control by X) was observed to decline as the number of XA compound trials was increased.
This decline was more rapid if X and A were presented simultaneously, as opposed to serially (i.e., X before A; Experiment
1). Conditioned inhibition to X, as assessed by a summation test (Experiment 1) and a retardation test (Experiment 2), increased
with the number of XA trials and did so more quickly for simultaneous than for serial pairings of X and A. The results help
to clarify previously discrepant findings regarding factors that promote excitation versus inhibition with this protocol. 相似文献
16.
In two experiments, rats received preexposure to three compound flavor stimuli, AX, BX, and CX, where X represents a saline
solution. AX and BX were presented in alternation; CX, on a separate block of trials. The value of X was then modified, being
devalued by aversive conditioning in Experiment 1, and rendered valuable by the induction of a state of salt need in Experiment
2. When given a choice between BX and CX, the rats consumed more of BX than of CX in Experiment 1, and more of CX than of
BX in Experiment 2, suggesting that B and C differed in their ability to modulate the response governed by the X element.
It was suggested that blocked preexposure to CX reduces the salience of the C stimulus but that the salience of B is maintained
by preexposure in which BX is alternated with AX. The implications of this result for the phenomenon of perceptual learning
are discussed. 相似文献
17.
Two lick suppression experiments using rats were conducted to determine whether extinction of a punctate excitor in a particular
context would result in that context becoming a conditioned inhibitor, as defined by passing both summation and retardation
tests. The role of extinction trial spacing was investigated as a possible determinant of whether the extinction context would
become inhibitory. Experiment 1 demonstrated that, although inhibition was evident using either massed or spaced extinction trials, spaced trials reduced
measurable inhibition as assessed by the summation test, but trial spacing had no influence on retardation test performance.
Experiment 2 confirmed Experiment 1’s conclusions while controlling for the influence of latent inhibition on the retardation test. In Experiment 2, the context proved inhibitory only following massed extinction trials. These data suggest that, at least with select parameters,
an extinction context can become inhibitory. 相似文献
18.
Prior cuing treatments intended to alleviate the forgetting of a conditioned avexsion-to an odor were tested with 18-day-old rats. Previous experiments had shown that when such pups were conditioned with the use of a CS?/CS+ procedure, pretest presentation of the CS? or US, but not the CS+, alleviated the forgetting otherwise seen after a 3-h retention interval. In Experiment 1, it was determined that the forgetting was not alleviated if the GS? was either preceded or followed by presentation of the CS+, despite the fact that the CS?/CS+ ordering mimicked that of original conditioning. Experiment 2 was an examination of the balance of extinction and reactivation effects caused by presenting the CS+ for varying durations following the 3-h retention interval. The forgetting over this interval was alleviated if the CS+ was presented for 5 or 15 sec, but not 30 sec. With an increase in duration of exposure from 15 to 30 sec, the consequences of the CS+ as a prior cuing treatment apparently shifted from reactivation to extinction. Experiment 3 was a test of the interaction between the consequences of different lengths of CS+ exposure and the effectiveness of adding CS? to the CS+ as a reactivation treatment. The varied effectiveness of reactivation treatments is discussed interms of a change in stimulus conditions from training to reactivation. 相似文献
19.
Two experiments were conducted to examine the effects of US preexposure on differential conditioning of the rabbit’s nictitating membrane response. Both experiments consisted of three phases: a 10-day US preexposure phase, a 7-day differential conditioning phase, and a 3-day retardation of learning test for inhibition. In Experiment 1, US preexposures retarded the development of excitation to CS+ but facilitated the development of inhibition to CS?. In Experiment 2, half of the preexposed subjects received the preexposures in one experimental environment and differential conditioning in a second environment. The remaining preexposed subjects received both phases in a single environment. Retarded excitatory and facilitated inhibitory conditioning were observed only in the preexposed subjects that received both phases in the same environment. Rabbits that received a context shift performed at control levels. The results are discussed in terms of current theories of US preexposure effects, and the best account was provided by a modified associative theory. 相似文献
20.
The within-compound association approach has been proposed as an account of synergistic conditioning in flavor aversion learning.
One prediction from the within-compound association approach is that following taste + odor compound conditioning, postconditioning
inflation of one element of the compound should increase responding to the second element. In four experiments with rats,
the AX+/A+ design was used to determine whether postconditioning inflation of A would increase responding to X. In Experiments
1 and 3, responding to X was significantly stronger after AX+/A+ conditioning, as compared with AX+ conditioning. In Experiments
2 and 4, the specificity of the inflation effect was demonstrated, because AX+/A+ conditioning produced a stronger aversion
to X than did AX+/B+ conditioning. Furthermore, it appears that the taste + odor association is symmetrical because inflation
of the taste aversion increased responding to the odor (Experiments 1 and 2) and inflation of the odor aversion increased
responding to the taste (Experiments 3 and 4). 相似文献