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1.
Three experiments showed a savings procedure to be an effective and sensitive alternative to sensory preconditioning procedures as a measure of associations among neutral stimuli. Experiment 1 showed that within-compound associations developed more rapidly in reinforced appetitive serial compound conditioning when nonreinforced preexposure to the serial compound was given than when separate element or no preexposure was given. Experiment 2 showed the savings effect to be highly stimulus specific. Experiment 3 examined the facilitation of serial compound conditioning after either simultaneous or serial nonreinforced preexposure to the elements of the compound. The results of that experiment were consistent with those of analogous sensory preconditioning experiments. When preexposure involved only the two elements of the subsequently reinforced compound, serial preexposure produced more savings than simultaneous preexposure. But when preexposure involved a three-stimulus procedure like that used by Rescorla (1980b), simultaneous preexposure resulted in more savings. Advantages of the savings procedure over sensory preconditioning as a measure of association among neutral stimuli are discussed. 相似文献
2.
Three experiments with rat subjects examined the development of simultaneous and serial feature-positive discriminations in appetitive conditioning. In Experiment 1, reinforced presentations of a simultaneous light-tone compound were intermixed with nonreinforced presentations of either the light or the tone. The compound stimulus acquired conditioned behaviors of a form characteristic of the predictive feature alone; the element common to reinforced and nonreinforced trials did not evoke conditioned behavior. In Experiment 2, reinforced presentations of a serial light-trace-tone compound were intermixed with nonreinforced tone-alone presentations. The light feature stimulus acquired conditioned behaviors characteristic of visual CSs. The tone stimulus, common to reinforced and nonreinforced trials, evoked conditioned behaviors characteristic of auditory CSs, but only when preceded by the light. In Experiment 3, variations in the interval between the light and tone on reinforced trials had little effect on responding to the light CS but substantially altered the pattern of responding to the tone CS. These results suggested that simultaneous and serial feature-positive discriminations may be solved differently. Performance in simultaneous feature-positive discriminations may be determined solely by associations between the feature stimulus and the reinforcer, but performance in serial discriminations may also involve the acquisition of a conditional cue function to the feature. 相似文献
3.
Pigeons were given successive discrimination training in which pecking during a choice period when the key was white was either reinforced or not, depending upon the prior presence or absence of a discriminative stimulus, which was a two-element serial compound. The compound consisted of a keylight and food, with food presented second or first in a forward or backward pairing for different groups of pigeons. In Experiment 1, the sequence was an S+ indicating reinforced trials, while in Experiment 2, the sequence was an S? indicating nonreinforced trials. Following acquisition of discriminated operant behavior, a sequence generalization test was administered during which all possible orders of the two stimuli were presented on test trials prior to the onset of the choice period. The results showed that food overshadowed stimulus control by the color of the light on the key on the sequence-generalization test, independently of whether food was presented first or second during training and independently of whether food was associated with reinforcement or nonreinforcement. The similarity of results for the two experiments suggests that overshadowing occurs independently of whether the compound is a discriminative stimulus for reinforcement or nonreinforcement. Simultaneous presentation of elements of a compound stimulus is not necessary for overshadowing because the phenomenon was captured with sequentially presented stimuli. 相似文献
4.
Three experiments examined rats’ ability to discriminate a compound conditioned stimulus (CS) from the individual elements of that compound in a flavor aversion conditioning paradigm. In Experiment 1, presentations of a compound of sucrose and saline solutions were followed by lithium chloride injections, but presentations of those elements individually were nonrein-forced (positive patterning). Conversely, in Experiments 2 and 3, presentations of the individual elements were followed by lithium chloride injection, but compound presentations were non-reinforced (negative patterning). The discriminations were acquired in all three experiments. In addition, all three experiments investigated the effects of preexposure of the discriminative stimuli on subsequent acquisition of the patterned discriminations. In positive patterning, preexposure had no measurable effect on the acquisition of responding (suppression) to the reinforced compound stimulus, but slowed the loss of suppression to the nonreinforced elements. In negative patterning, preexposure slowed the acquisition of suppression to the reinforced elements but had little effect on the loss of suppression to the nonreinforced compound. 相似文献
5.
In Experiment 1, rats were trained to leverpress on a variable ratio (VR) 30 schedule with a 500-msec delay between the reinforced response and food delivery. Subjects that experienced a signal during the delay responded faster than did control subjects that received the stimulus un-correlated with reinforcement. Higher response rates were obtained when the stimulus used to signal reinforcement was auditory rather than visual. Experiments 2 and 3 compared the effects of signaling reinforcement with either a localized or a diffuse light on responding maintained by VR schedules of reinforcement. Elevated response rates were observed with the diffuse stimulus, but the localized stimulus failed to produce such potentiation. Experiment 3 also examined the conditioned reinforcing power of localized and diffuse visual stimuli. These results are discussed with reference to (1) theories of selective association and sign tracking and (2) their implications for current theories of signaling reinforcement. 相似文献
6.
Robert A. Rescorla 《Learning & behavior》1997,25(2):200-209
In five experiments, rats were given Pavlovian pairings of auditory and visual stimuli with delivery of food pellets. Experiment 1 found greater responding to an AB compound after training with the individual A and B stimuli, compared with responding both to the A and B elements and to a separately trained CD compound. Experiment 2 found this enhanced responding to depend on the associative strengths of A and B. In Experiment 3, responding was greater to a CD compound than to the other compounds after an AB-, AD+, BC+ training procedure. In Experiment 4, responding to an AB compound was greater than that to the elements after A was reinforced on a 100% schedule and B on a 50% schedule. In Experiment 5, responding to an AC compound was greater than that to either A or C after an AB+, CD+, A-training procedure. A configural theory, such as that proposed by Pearce (1987), anticipates summation in none of these procedures, unless the conditioned context is assumed to have a salience greater than zero. In order to predict summation in Experiments 3, 4, and 5, a context salience greater than that of the elements must be assumed. However, such an assumption also anticipates that extinction of a 100% stimulus should eliminate responding to a 50% stimulus. The results of Experiment 3 contradicted that prediction. These results conform better to the expectations of elemental models of conditioning. 相似文献
7.
Nonreinforced exposure to a nontarget stimulus that was followed by nonreinforced exposure to a target/nontarget simultaneous
compound stimulus resulted in enhanced latent inhibition of the target. Conditioning was slower after this treatment than
after nonreinforced exposure to the target stimulus alone (Experiment 1). However, a salient auditory stimulus presented immediately
after the compound in the second phase reduced levels of latent inhibition, relative to the enhanced latent inhibition produced
when no such extracompound stimulus was presented (Experiments 2 and 3). This effect was not noted if the salient auditory
cue was presented 10 sec after the termination of the compound stimulus (Experiment 4). In Experiment 5, there was no disruption
of simple latent inhibition produced by a salient stimulus. These results are consistent with enhanced latent inhibition’s
being produced by the formation of within-compound associations, which are disrupted by the salient extracompound stimuli. 相似文献
8.
Foraging honeybees were trained in a concurrent blocking design with a compound stimulus (AX) reinforced and one of its components (A) either reinforced for a blocking group or nonreinforced for a control group. In Experiment 1, a compound of two colors was used; in Experiment 2, a compound of two odors was used; in Experiment 3, a color-position compound, with position defined in terms of proximity to a distinctive visual landmark, was used; and, in Experiment 4, an odor-position compound was used. In each of the first three experiments, the blocking group responded less than did the control group in a subsequent test with X; in the fourth experiment, the two groups did not differ. The results are in accord with expectations based on those of previous experiments with honeybees in which the independence assumption was found to hold for intermodal compounds but not for intramodal compounds. 相似文献
9.
An attempt was madeto manipulate the strength of internal stimulus representations by exposing pigeons to brief delays between sample offset and comparison onset in a delayed conditional discrimination. In Experiment 1, pigeons were first trained on delayed conditional discrimination with either short (0.5-sec) delays or no delays. When delays were increased by 2.0 sec, birds trained with a delay performed at a higher level than did birds trained with no delays. In Experiment 2, subjects were first trained on a delayed simple discrimination. Following a circle stimulus, responses to a white key were reinforced; however, following a dot stimulus, responses to the white key were not reinforced. The pigeons were then trained on a delayed conditional discrimination involving hue samples and line-orientation comparisons with differential outcomes. Choice of vertical following red yielded food; choice of horizontal following green yielded no food. Mixed delays were then introduced to birds in Group Delay, whereas birds in the control group received overtraining. When tested on a delayed simple discrimination with hue stimuli (red and green initial stimuli followed by white response stimulus), pigeons in Group Delay tended to perform at a higher level than did birds in the control group (i.e., although the birds in both groups responded more following red than following green, birds in Group Delay did this to a greater extent than did birds in the control group). Thus, experience with delays appears to strengthen stimulus representations established during training. 相似文献
10.
Three experiments on classical differential conditioning of the human skin conductance response to elemental and compound stimuli are reported. Subjects in Experiment 1 received both positive and negative patterning training, followed by either positive or negative patterning transfer tests on new stimuli. In positive patterning, a compound of two stimuli is reinforced and its elements are nonreinforced. In negative patterning, the elements are reinforced and the compound is nonreinforced. Subjects in Experiments 2 and 3 received either positive or negative patterning during training, followed by transfer tests on new stimuli. In Experiment 2, the transfer series began with new elements, after which their compound was presented; in Experiment 3, the new compound was presented first in the transfer series, and then the separate elements were administered. All three experiments provided evidence of the acquisition of positive patterning, while negative patterning was found only in Experiments 2 and 3. Positive patterning transferred to new stimuli, indicating that it was not attributable solely to summation of sub-threshold excitation conditioned to the elements on reinforced compound trials. This finding, coupled with the negative patterning found in Experiments 2 and 3, provided support for the unique cue hypothesis. It was concluded that the assumed unique cue constituted a learned “rule,” and that the actual elemental stimuli were neither perceptually nor otherwise modified during the conditioning process. 相似文献
11.
In Experiment 1, it was shown that generalization testing following successive discrimination training between two closely spaced wavelengths results in a sharp gradient with a peak of responding shifted from S+ so as to be further removed from S?. Testing after a 24-h delay resulted in a flatter gradient with greater peak (and area) shift. A 5-min pretest exposure to S+, reinforced or unreinforced, or to S? (unreinforced) reinstated immediate test performance; free reinforcement with no discriminative stimulus present had no such effect. Experiment 2 replicated the flattening of generalization gradients and enhanced peak shift in delayed testing. Free feeding in a pretest treatment with a distinctive food uniquely associated with the wavelength discrimination problem failed to reinstate immediate test performance. Experiment 3 tested the hypothesis that free feeding failed as a reactivation treatment because it did not engender keypecking. Subjects were trained to peck a vertical line stimulus before being given wavelength discrimination training. Again, the enhanced peak shift and greater flattening with delayed wavelength generalization testing was found. A pretest exposure to the vertical line stimulus elicited pecking but had no effect on subsequent wavelength generalization. Thus, only a reactivation treatment that included one of the discrimination training stimuli was effective in producing delayed test performance comparable to that obtained in an immediate test. 相似文献
12.
Ruth M. Colwill 《Learning & behavior》1991,19(4):326-336
Three experiments using rats examined whether a signal for the nonreinforcement of an instrumental response (S-) provided information about the identity of the omitted outcome. In all three experiments, one stimulus was established as a signal for the nonreinforcement of a response that earned food pellets and another stimulus signaled the nonreinforcement of a response that earned liquid sucrose. Experiment 1 found that each S-suppressed another instrumental response trained with the same outcome significantly more than a response trained with a different outcome. Using a variant of this transfer design, Experiment 2 demonstrated that an S- was slower to develop discriminative control over a new response reinforced in its presence with the same outcome compared with an outcome different from the one whose omission-the S- had previously signaled. Experiment 3 examined transfer of the S- stimuli to a response trained with two outcomes, one of which had subsequently been devalued. Performance of this response significantly increased in the presence of a signal for the omission of the devalued outcome, but decreased in the presence of a signal for the omission of the valued outcome. These results suggest that S-s do provide information about the identity of omitted response-contingent outcomes. 相似文献
13.
Two experiments with rat subjects examined conditioning of an aversion to a compound flavor stimulus after preexposing the compound, its constituent elements, or no explicit flavor stimulus. Experiment 1 used a short-term procedure in which preexposure and conditioning treatments occurred on the same day; Experiment 2 used a long-term procedure in which more extensive preexposure was administered several days before conditioning. In both experiments, preexposure of the elements slowed conditioning to the compound more than did preexposure of the compound itself. These effects were apparently not mediated by changes in pseudoconditioned or neophobic responses. The results were related to Lubow’s conditioned attention theory of stimulus preexposure effects. 相似文献
14.
James V. Couch 《Learning & behavior》1975,3(4):347-358
Two experiments examined the presumed relationship between behavioral contrast and inhibitory stimulus control. In Experiment I, pigeons were exposed to mult VI 1-min VI 1-min or mult VI 5-min VI 5-min during baseline training prior to mult VI 1-min VI 5-min discrimination training. Half of the subjects received a timeout (TO) component during baseline in order to reduce the degree of contrast during discrimination training. Only 3 of 8 subjects receiving the TO showed contrast while all other subjects showed various degrees of contrast. Postdiscrimination generalization gradients indicated excitatory rather than inhibitory control by the stimulus associated with the VI 5-min schedule. During baseline training in Experiment II, responding to all the generalization stimuli was reinforced. In addition, some subjects received the TO stimulus. The subjects were next exposed to mult VI 1-min EXT, mult VI 1-min VI 5-min, or just the VI 5-min component. Generalization gradients indicated inhibitory control by the stimulus associated with EXT or VI 5-min for 19 of 20 subjects even though some subjects did not show contrast. These results question the presumed relationship between behavioral contrast and inhibitory stimulus control. 相似文献
15.
In two experiments, a maintained generalization procedure was employed to examine stimulus control of pigeons’ responses to a visual wavelength continuum. For both experiments, pigeons’ responses were periodically reinforced during wavelength values from one end of a continuum, while responses during other stimulus values were extinguished. In Experiment 1, the set of positive stimulus values remained constant, while the spacing of the set of negative stimuli varied. In Experiment 2, the set of negative stimulus values remained constant, while the spacing of positive stimuli varied. Positive dimensional contrast effects were obtained in both experiments. In general, the results indicated that variation in the spacing of negative stimuli had little effect on positive dimensional contrast. However, variation in the spacing of positive stimuli produced changes in the peak of the dimensional contrast gradient, without apparent change in the magnitude of the effect. 相似文献
16.
In four experiments, rats were trained on different patterning discriminations before being tested with compounds composed of novel combinations of the trained stimuli. In Experiment 1, rats were trained on a negative-patterning schedule (A+ B+ AB-) intermixed with reinforced presentations of a second compound (CD+). On a subsequent test, the rats responded more to two novel compounds, AC and BD, than to A and B, but less than to CD. In Experiment 2, rats were trained on two concurrent negative-patterning discriminations (A+ B+ AB-, C+ D+ CD-). On test, they responded more to AC and BD than to AB and CD, but less than to the single stimuli. In Experiment 3, rats were trained on two concurrent positive-patterning discriminations (A-B- AB+, C- D- CD+). On test, their response rates to AC and BD were not different from the response rates to the trained compounds (AB and CD). Finally, in Experiment 4, rats were trained on a positive- and negative-patterning discrimination concurrently. Once again, on test, response rates to AC and BD were not different from responding on reinforced trials of the trained discriminations (A+, B+, and CD+). We discuss the implications of these findings for elemental and configural models of stimulus representation. 相似文献
17.
In the present experiments, we examined the role of within-compound associations in the interaction of the overshadowing procedure
with conditioned stimulus (CS) duration, using a conditioned suppression procedure with rats. In Experiment 1, we found that,
with elemental reinforced training, conditioned suppression to the target stimulus decreased as CS duration increased (i.e.,
the CS duration effect), whereas, with compound reinforced training (i.e., the overshadowing procedure), conditioned suppression to the target stimulus
increased as CS duration increased. In subsequent experiments, we replicated these findings with sensory preconditioning and
demonstrated that extinction of the overshadowing stimulus results in retrospective revaluation with short CSs and in mediated
extinction with long CSs. These results highlight the role of the duration of the stimulus in behavioral control. Moreover,
these results illuminate one cause (the CS duration) of whether retrospective revaluation or mediated extinction will be observed. 相似文献
18.
Blough DS 《Learning & behavior》2004,32(2):157-172
In three experiments with pigeons, the similarity of unreinforced test stimuli to a reinforced stimulus and the frequency
of reinforcement associated with a stimulus were varied. The stimulus on each trial was a small spot that appeared in different
hues or, in Experiment 3, different forms. Differential response frequency and reaction time (RT) patterns emerged: Changes
in similarity affected the percentage of stimuli responded to but left the shape of RT distributions about the same, whereas
changes in reinforcement shifted RT distributions but had little effect on the percentage of responses. When the similarity
and reinforcement variables were applied to the same stimuli (Experiment 2), their effects were largely independent. A generalization
procedure (Experiment 3) replicated the similarity effects of the initial discrimination procedure. The RT distributions were
modeled by a diffusion process, and implications for a memory-instance model were suggested. 相似文献
19.
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
20.
In two conditioned lick suppression experiments with rats, we examined the permanence of the overshadowing effect as a function of the number of compound reinforced training trials. In Experiment 1, robust overshadowing was observed following 4 compound-US pairings but dissipated with 36 pairings. Overshadowing decreased because responding to the overshadowed stimulus increased, not because responding by the control group decreased. This dissipation was stimulus specific and not attributable to a response ceiling. Experiment 2 extended the generality of the effect to a sensory preconditioning design and further demonstrated that overshadowing lost through many compound-US pairings was restored by posttraining extinction of the training context. The results are explicable in terms of the extended comparator hypothesis (Denniston, Savastano, & Miller, 2001) under the assumption that the impacts of first- and second-order comparator processes grow differentially as a function of number of trials. 相似文献