共查询到20条相似文献，搜索用时 47 毫秒
1.
Adult rats were injected with lithium chloride (LiCl) after consumption of a novel flavor (chocolate milk) that either was or was not presented together with a novel ambient odor (banana) as a compound conditioned stimulus (CS). In Experiment 1, the adults’ consumption of the flavor 24 h after conditioning was compared with that of weanling rats given the same conditioning treatment on Postnatal Day 21. The results confirmed previous indications that the reduction in aversion observed for adults conditioned with the compound CS (overshadowing) was weak or nonexistent in weanlings. After a longer retention interval (21 days), there was no evidence of overshadowing in adults despite maintained retention of the basic conditioned aversion. In Experiment 2 this decrease in overshadowing after a long retention interval was replicated with adult animals and extended to a different method of testing. The form of the effect was the same as in Experiment 1: The decrease in overshadowing occurred over the retention interval without loss in retention of the basic taste aversion; the decrease in overshadowing was a consequence of anincrease in the flavor aversion displayed by animals conditioned with the compound CS. The impaired flavor aversion (i.e., the overshadowing) observed shortly after conditioning apparently was due to factors associated with memory retrieval, rather than to reduced attentional or associative strength. 相似文献
2.
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
3.
The effects of flavor preexposure and retention interval were assessed in 6- and 12-day-old rats. Conditioned aversions to a flavor appeared at both ages. The conditioning of the younger pups was unaffected by conditioned stimulus (CS) preexposure and was not evident after a 10-day retention interval. For the 12-day-old rats, preexposure to either the flavor CS or a different flavor attenuated aversion strength when the rats were tested soon after conditioning. Other 12-day-old rats that were tested 10 days after conditioning also expressed substantial aversions, but with a retention interval of this length, the aversions were equivalent for animals preexposed to the CS and those not preexposed before conditioning. This loss of the CS-preexposure effect over a long interval, which has also been observed in adult rats, identifies the locus of this effect as postacquisition and perhaps at the stage of memory retrieval. 相似文献
4.
In two experiments, rats (n = 228) received pretraining access to a distinctive novel flavor (saline) followed by aversion conditioning to a different novel conditioned stimulus (CS) (saccharin). Then the rats were tested for aversion to the CS (saccharin) or for conditioning-enhanced neophobia to a third novel flavor (casein hydrolysate). Pretraining access to a distinctive novel flavor that differed from the CS reliably reduced the magnitude of conditioning-enhanced neophobia to casein, but did not reliably affect conditioned aversion effects to the CS. Pretraining access to the CS reduced aversion effects to the CS and reduced postconditioning neophobia to casein to the performance level shown by ingestion-toxin controls. Results were consistent with the view (Braveman & Jarvis, 1978) that conditioned aversion and neophobia may be independent phenomena with separable underlying mechanisms. 相似文献
5.
In two experiments, the influence of exposure to a CS? on the acquisition and retention of a conditioned odor aversion was examined. Preweanling rats were given exposure to the CS? either prior to (CS?/CS+) or following (CS + /CS?) the pairing of a second odor (the CS+) with footshock. The results of Experiment 1 indicated that subjects in both of the treatment conditions acquired aversions of comparable strength to the odor paired with footshock and that retention of the odor aversion was not affected by order of stimulus presentation during conditioning. Experiment 2 indicated, however, that the effectiveness of pretest exposure to various elements of the conditioning episode in reactivation of the memory for conditioningwas dependent on the order of stimulus presentation during conditioning. This differential effectiveness of the various reactivation treatments is discussed in terms of their relationship to the associative “status” of the stimuli present during conditioning and in terms of the information provided to the animal by the reactivation treatment. 相似文献
6.
Batsell WR Wakefield E Ulrey LA Reimink K Rowe SL Dexheimer S 《Learning & behavior》2012,40(2):180-194
The present series of five flavor aversion experiments with rat subjects examined compound conditioning at varying CS-US intervals. Using a taste-taste design, Experiments 1A and 1B demonstrated overshadowing at a 0-min CS-US interval and potentiation at a 120-min CS-US interval, and these effects occurred with both tastes of the compound. Experiment 2 showed that the aversion to a single element is reduced when the CS-US interval is increased to 120 min, but the aversion for a compound taste is not. Experiments 3A and 3B explored odor + taste compound conditioning; the results demonstrated odor potentiation across the trace interval and a transition from taste overshadowing to taste potentiation. Collectively, the data show that the change from overshadowing to potentiation was not due to changes in the aversions produced by compound conditioning but, instead, was due to a more rapid loss of conditionability across a trace interval prior to the US in single-element conditioning. These experiments suggest that following compound conditioning, the aversion to each element represents generalization decrement from the configured compound, but the designation of overshadowing or potentiation actually depends on the status of conditioning in the single-element control. 相似文献
7.
Although a number of studies have demonstrated nearly complete retention of fear in a conditioned suppression task, they provide little information about the nature of the memory for the CS. The purpose of the present experiment was to investigate the retention of an attribute of a tonal CS that had been paired with shock and was thus capable of eliciting a conditioned emotional response (CER) in rats. The Kamin blocking effect was utilized to detect changes in the memory of CS attributes. Either 1 or 21 days following conditioning to a tone, separate groups of rats received compound conditioning in which either the original or a novel tone was combined with a light. Subsequent measurement of suppression to the added element (light) indicated that only the original CS produced blocking at the short delay, but that both original and novel tones resulted in blocking at the 21-day interval. This increase in the extent of blocking suggests that memory for specific attributes of the CS does diminish as a function of time. 相似文献
8.
Two experiments examined the effects of nonreinforced flavor exposure on the strength of a conditioned taste aversion. Rats were conditioned by pairing maple flavor with LiC1. Prior to or subsequent to this pairing, some animals received nonreinforced exposure to either maple or saccharin. In separate subjects, preference for maple was tested 1 or 21 days after the last training episode. In the first experiment, the nonreinforced stimulus exposure occurred before conditioning (latent inhibition, or LI, procedure); in the second experiment, the nonreinforced exposure occurred after conditioning (extinction, or EXT, training). In both experiments, nonreinforced exposure to maple or saccharin reduced the magnitude of a conditioned maple aversion when testing occurred soon after conditioning. When testing was delayed, however, the attenuation due to nonreinforced saccharin exposure dissipated, both with the LI procedure and with EXT. In contrast, the nonreinforced exposure to maple was found to attenuate conditioned reactions at both short and long retention intervals. The release from generalized LI and spontaneous recovery following generalized EXT training are discussed in terms of retrieval processing. The possibility that the same mechanism may underlie LI and EXT is considered. 相似文献
9.
Joint presentations of a conditioned stimulus (CS) and an unconditioned stimulus (US) strengthen the contingency between them, whereas presentations of one stimulus without the other degrade this contingency. For example, the CS can be presented without the US either before conditioning (CS–no US and then CS–US; latent inhibition) or after conditioning (CS–US and then CS–no US; extinction). In vertebrate subjects and several invertebrate species, a time lapse usually results in a return of the conditioned response, or spontaneous recovery. However, in land mollusks, spontaneous recovery from extinction has only recently been reported, and response recovery after latent inhibition has not been reported. In two experiments, using conditioned aversion to a food odor as a measure of learning and memory retention, we observed contingency degradation via latent inhibition (Experiment 1) and extinction (Experiment 2) in the common garden slug, Lehmannia valentiana. In both situations, the contingency degradation procedure successfully attenuated conditioned responding, and delaying testing by several days resulted in recovery of the conditioned response. This suggests that the CS–US association survived the degradation manipulation and was retained over an interval of several days. 相似文献
10.
Richard V. Krane 《Learning & behavior》1980,8(4):513-523
The types of conditioned properties acquired by novel (i.e., nonpreexposed) or familiar (i.e., preexposed) exteroceptive cues that were paired with toxicosis, in the absence of a flavor CS, were evaluated in four experiments. In Experiment 1, the conditioned properties of novel exteroceptive cues served to block the acquisition of an aversion to a flavor CS during flavor conditioning and to suppress the ingestion response during flavor testing; animals failed to suppress their ingestion of either the flavor CS or a neutral flavor when tested in the absence of the exteroceptive CS, but suppressed their ingestion of both the flavor CS and the neutral flavor when tested in the presence of the exteroceptive CS. In Experiment 2, preexposed exteroceptive cues that had been paired with toxicosis failed to provide evidence of such conditioned properties. Experiment 3 demonstrated that preexposed contextual cues that were reinforced in compound with novel exteroceptive cues failed to acquire the conditioned properties acquired by nonpreexposed contextual cues under the same conditions of reinforcement. Finally, in Experiment 4, the conditioned properties of the novel exteroceptive cues served to evoke a conditioned gastrointestinal response that gradually extinguished as a function of repeated nonreinforced exposures to the exteroceptive cues, and, in the absence of such extinction, the conditioned properties served to block the acquisition of a flavor aversion. 相似文献
11.
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
12.
In six experiments, we examined taste and compound taste/taste aversions at different retention intervals. In Experiment 1, saccharin aversions were significantly weaker 1 day after conditioning than 21 days after conditioning. This effect was determined not to be caused by the aftereffects of illness or differential hydration. With the use of a saccharin/denatonium compound, Experiment 2 demonstrated overshadowing of a denatonium aversion at 21- and 1-day retention intervals, Experiment 4 showed a potentiated saccharin aversion only at the 21-day retention interval, and both Experiments 2 and 4 revealed that the aversion of the taste-only controls was stronger at the later retention interval. Experiments 3 and 5 demonstrated that the differences at the two retention intervals were not caused by unconditioned changes in taste preference. Finally, Experiment 6 showed that extinction of the conditioning environment prior to testing results in stronger saccharin aversions than occur in nonextinguished controls. Collectively, these experiments suggest that testing within a 24-h period after conditioning will result in significantly weaker taste aversions. Also, these results support a retrieval-competition explanation that may account for the weakened aversions at the 1-day testing interval of both groups conditioned to single elements and those conditioned to compounds. 相似文献
13.
In three experiments with rats, taste + odor interactions in compound aversion conditioning were investigated. In Experiment 1, two odors (0.02% almond and 0.02% orange) were compared on single-element odor aversions, taste (denatonium) potentiated odor aversions, and potentiated odor aversions following taste extinction. Although no odor differences were seen following single-element conditioning, both types of potentiated orange odor aversions were stronger than their almond odor counterparts. These data show that odors of similar conditionability are differentially potentiated by the same taste. To determine whether these differences were due to unique perceptual representations, the effects of elemental extinction or compound extinction on aversions to the compound were investigated in Experiments 2 and 3. In Experiment 2, orange odor extinction weakened responding to the compound significantly more than taste extinction did. In contrast, almond odor extinction and taste extinction produced similar decrements in responding to the compound in Experiment 3. These results suggest that the perceptual representation of these specific taste + odor compounds are different, and they are discussed in regard to configural and within-compound association accounts of potentiation. 相似文献
14.
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
15.
A series of experiments was conducted to examine the phenomenon of potentiation. Experiment 1 demonstrated potentiation of odor aversions by taste when morphine served as the unconditioned stimulus (US). Experiment 2 provided evidence that the observed potentiation was due to a within-event association between odor and taste stimuli, rather than reflecting an enhanced odor-morphine association. In Experiment 3, morphine supported place conditioning to contextual cues and aversive conditioning to a taste cue, but potentiation of place conditioning by a taste cue was not obtained. Apparently the absence of potentiation was due to the dual nature of the morphine US, as potentiation of a contextual aversion by taste was obtained in Experiment 4 when a strictly aversive US (lithium) was used. These data suggest that potentiation depends on (1) an initially weak association between the to-be-potentiated conditioned stimulus (CS) element and the US, and (2) the elicitation of qualitatively similar responses by the individual elements of the CS compound. Collectively, these results support an explanation of potentiation based on within-event learning. 相似文献
16.
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
17.
Animals were first conditioned to expect lithium treatment following exposure to one taste solution (the CS+) and to expect no drug treatment following exposure to another flavor (the CS?). All subjects then received a saccharin taste-aversion conditioning trial. In Experiment 1, this conditioning trial was preceded 0, 1, 2, 4, or 6 h earlier by exposure to the CS+ flavor for independent groups. The CS+ exposure attenuated saccharin aversion learning if it occurred immediately before the saccharin conditioning trial but not if it occurred 1 h or more before conditioning. In Experiment 2, the saccharin conditioning trial was preceded 3 or 4.5 h earlier by a lithium injection. This proximal US preexposure injection was either unannounced (Li) or preceded by exposure to the CS+ (CS+Li) or the CS? (CS?Li) stimuli. The US preexposure attenuated saccharin aversion learning in all cases. However, the interference effect was less when the preexposure injection was expected (CS+Li) than when it was unexpected (CS?Li). This outcome could not be explained in terms of direct effects of the CS+ and CS? stimuli on the saccharin conditioning trial, and shows that the proximal US preexposure effect is a function of not only the drug dosage and preexposure interval, but also the anticipation of the drug pretreatment. 相似文献
18.
Rats were used in a conditioned taste aversion procedure in order to examine the effects of context exposure duration during
the conditioning sessions on conditioned responding. One flavor was paired with lithium chloride during a long session in
one context, whereas another flavor was conditioned during a short session in another context. Testing occurred in the home
cage. The results showed that conditioning during short sessions produced strong conditioned taste aversions. Conditioning
during long sessions produced strong conditioned taste aversions when the conditioned-stimulus-unconditionedstimulus (CS-US)
pairing occurred at the end of the lengthy session. Other results showed that context-US associations were formed during the
short duration sessions and that these associations supported conditioned responding to the CS trained in that context. The
results are discussed with respect to the different influences that contextual cues can exert on conditioned responding. 相似文献
19.
Rats were used to examine the extent to which extinction of an acquired conditioned taste aversion retards subsequent reacquisition. A saccharin-flavored solution (sac) was paired with LiCl and then followed by CS-alone extinction trials with this flavor. A control group received a different flavor, decaffeinated-coffee (coff), during initial conditioning and extinction. Sac was then paired with LiCl for all rats during a second conditioning phase. Reacquisition of the aversion to sac was retarded relative to the acquisition of an aversion to sac by the control group. A similar experiment with fewer extinction trials, but still with complete loss of the initial aversion, did not obtain slow reacquisition. The results are discussed with respect to an interference view of extinction and the slow-reacquisition effect. 相似文献
20.
In three experiments using rats as subjects, we investigated the degree to which a conditioned flavor aversion transfers from one context to another. Experiment 1, using a one-trial conditioning procedure, found no effect of a change of context on a conditioned aversion. Experiment 2 employed a multitrial procedure and demonstrated that a conditioned aversion was extinguished more rapidly after a change of context. Experiment 3 showed that context change decreased the effectiveness with which a conditioned flavor could block acquisition of an aversion by a second flavor. It is argued that these data cannot be explained in associative terms, and that they constitute evidence of conditionality in a simple aversive conditioning procedure. 相似文献