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1.
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
2.
Michael Domjan 《Learning & behavior》1978,6(2):133-142
Taste aversions were conditioned by exposing subjects to a 1.0% saccharin solution 30 min after an injection of lithium chloride. The aversion learning was disrupted if subjects had also received an additional lithium injection some time earlier (Experiments 1–3). This interference effect of US preexposure was a decreasing function of the preexposure interval, beyond the optimal interval (105 min) for observing the phenomenon (Experiment 1), and was directly related to the dose of the preexposure injection (Experiment 2). No interference with conditioning occurred at short (e.g., 30-min) preexposure intervals (Experiment 1), probably because under these circumstances the preexposure injection itself conditioned a strong aversion (Experiment 4). At moderate (105-min) but not at short (30-min) preexposure intervals, the interference with aversions learned as a result of taste exposure following drug injection was comparable to the interference with learning in a more conventional forward conditioning procedure (Experiments 3 and 4). These findings are similar to previously documented effects of proximal CS- and US-preexposure and are consistent with recent stimulus rehearsal and opponent-process theories. 相似文献
3.
Experiment 1 investigated the effects of US habituation on the acquisition and extinction of learned taste aversions in rats. Subjects receiving five noncontingent LiCl intubations prior to conditioning failed to develop a conditioned taste aversion, while control subjects experiencing a single saccharin/LiCl pairing displayed a pronounced taste aversion which weakened during subsequent poisonings. Experiment 2 examined whether habituation, defined as a waning of responses to repeated presentation of an illness stimulus, was a possible mechanism for explaining the results of Experiment 1. Subjects showed a decrease in motor activity following an initial LiCl intubation, but less attenuation of activity with successive intubations. 相似文献
4.
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
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.
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
7.
Rescorla RA 《Learning & behavior》2008,36(2):67-74
Three experiments used a compound test procedure to evaluate whether superior conditioning results from the pairing of stimuli that are related to each other. In each case, a stimulus compound was tested after its component conditioned stimuli (CSs) had been conditioned by the same unconditioned stimuli (USs) arranged such that either related or unrelated CSs and USs were paired. Experiment 1 explored auditory and gustatory stimuli conditioned by LiCl or shock, using rats. Experiments 2 and 3 used second-order conditioning in pigeons to pair stimuli that were similar by virtue either of qualitative features or of shared physical location. In each case, the compound test provided clear evidence that pairing related stimuli produces superior associative learning. 相似文献
8.
In two experiments, we examined the conditions under which signaling an unconditioned stimulus (US) with a nominal conditioned stimulus (CS) interferes with the conditioning of situational cues in defensive freezing in the rat. Subjects received footshock USs that were (1) either signaled or unsignaled and (2) either varied or fixed in their temporal location within the conditioning session. Experiment 1, with only one trial per session, yielded no evidence that signaling affected pretrial freezing using either a fixed or variable interval between placement in the context and shock onset. In a test in which no CSs or footshocks were presented, groups that previously had received footshock at a fixed temporal location showed greatest freezing at around that same time. For groups that had received footshocks at various times, freezing declined across the test session. Experiment 2 showed overshadowing of pretrial freezing after more extensive conditioning with many trials per session, but only if the intershock intervals were variable rather than fixed. 相似文献
9.
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
10.
Michael Domjan 《Learning & behavior》1975,3(3):205-211
Rats repeatedly injected with lithium chloride were subsequently tested drinking novel and familiar solutions of both casein hydrolysate and vinegar. Injections in the absence of edibles result in only a small, and sometimes not reliable, increased avoidance of the novel casein and vinegar solutions. In contrast, if subjects acquired an aversion to saccharin as a result of the lithium injections, this learned aversion generalized to casein hydrolysate, with the generalization greatly enhanced by novelty of the casein flavor. However, the saccharin aversions did not generalize to the novel vinegar solution nearly as much as to the novel casein flavor. These results suggest that previous observations of poison-induced neophobia were probably in part a result of the stimulus generalization of conditioned taste aversions and that in addition to test stimulus novelty some other factor, such as stimulus salience or similarity to the conditioned aversive flavor, is also involved in the generalization of learned taste aversions. 相似文献
11.
Joseph W. Ternes 《Learning & behavior》1976,4(3):317-321
Sixteen rats were maintained out of doors in cages with natural light, temperature, and social stimulation for 3 months. Subsequently, by pairing the taste of sucrose with IP injections of LiCl, the rats were conditioned to avoid sucrose. Each of four groups of rats received the CS-US pairing at a different time of day. Times of conditioning were 6 a.m., 12 a.m., 6 p.m. and 12 p.m. EST. A two-bottle preference test between 4% sucrose solution and tap water was initiated 24-h after conditioning. Daily measurements of preference were continued for 16 consecutive days. Results indicated that, although all groups initially exhibited equivalent sucrose aversions, the groups conditioned at 12 a.m. and 6 p.m. extinguished within 12 days while the 6 a.m. and 12 p.m. groups continued to manifest profound aversions for sucrose throughout the 16 test days. 相似文献
12.
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
13.
Rats received either a small or a large amount of a novel saccharin solution prior to a conditioning episode in which the saccharin flavor was paired with lithium-induced toxicosis. When the time between the preexposure and the conditioning episode was 3.5 h, both the small and large amounts of saccharin decremented conditioning. However, when the time between the preexposure and the conditioning episode was 23.6 h, only the consumption of a large amount of saccharin decremented conditioning. In a second experiment, rats received either a short or a long exposure to the novel saccharin solution and were then given a choice test between the saccharin and water. Rats given the choice test immediately following their preexposure to saccharin avoided consuming it. If they received the choice test 4 h later, they consumed more of the saccharin irrespective of the length of the preexposure. In contrast, when they were given a choice test 24 h after the preexposure, only rats that had received a long preexposure displayed a significant preference for the saccharin. The present results demonstrate that the flavor preexposure effect and the attenuation of neophobia are both determined by the time between preexposure to the novel flavor and the conditioning episode or choice test and the amount of preexposure to the novel flavor. These findings are discussed in relation to the information-processing model developed by Wagner (1976, 1978) and are used to provide an account, in terms of this model, of the delay-gradient seen in flavor-aversion learning. 相似文献
14.
We showed, as had previous investigators, that young rats formed taste-sickness associations that were weaker than those of mature rats; associations were not formed over a delay greater than 45 min, and aversions did not survive a 60-min test session. The difficulty young rats had withholding consumption and their poor sensitivity to taste and sickness contributed to the weak aversions. Choice tests revealed aversions that had apparently extinguished during a no-choice test, and animals that were allowed to mature prior to the first test readily withheld consumption for 60 min. Furthermore, young rats formed an aversion over a delay of 2.5 h when the concentrations of saccharin and lithium chloride were increased. Aversions to the stronger saccharin did not extinguish over two one-bottle tests and were retained for 52 days. 相似文献
15.
Water-deprived rats were given a single exposure to saccharin and LiCl, either paired or unpaired. Half the subjects then received three saccharin-only exposures (extinction) in the training enclosure, followed by a single LiCl-only presentation (unconditioned stimulus reinstatement) 8 days after conditioning. The remaining subjects received six saccharin-only exposures, followed by LiCl reinstatement 13 days after conditioning. In both cases LiCl reinstatement occurred outside the training/test context. Appreciable recovery from extinction was observed after the partial loss of taste aversion obtained with three extinction sessions and the 8-day conditioning-reinstatement interval, but not after the asymptotic loss of taste aversion obtained with six extinction sessions and the 13-day conditioning-reinstatement interval. Conditioned taste aversions appear to be similar to more traditional associations with respect to both extinction and reinstatement-induced recovery from extinction. The results are discussed with reference to the event-memory, contextual-conditioning, and facilitated-retrieval hypotheses of postextinction reinstatement effects. 相似文献
16.
On four occasions, Holtzman rats drank saccharin in a distinctive environment prior to lithium-induced toxicosis. Preconditioning exposure to saccharin either in the home cage or in the distinctive environment interfered significantly with the establishment of an environmental aversion. Animals preexposed to the experimental environment, however, showed environmental aversions substantially stronger than those in animals preexposed to saccharin and only slightly higher than those with no preexposure to either the taste or the environment. Subsequent saccharin tests revealed significantly stronger aversions in the group that received environmental preexposure than in any of the other groups. This pattern of outcomes demonstrates taste-mediated potentiation of novel and familiar environmental stimuli as well as overshadowing of the taste by novel environmental stimuli. Furthermore, it indicates that previous demonstrations of taste-mediated environmental potentiation involve facilitated conditioning of the environmental stimuli and decremented conditioning of the taste stimuli. 相似文献
17.
Second-order conditioning of social approach to a female conspecific in male Japanese quail was investigated in four experiments. Subjects that received paired first- and second-order trials acquired second-order conditioning in both Experiments 1 and 2. In contrast, subjects that received paired first-order but unpaired second-order trials, and subjects that received unpaired first-order but paired second-order trials, did not acquire second-order conditioning. In Experiment 3, subjects for whom the first-order conditioned stimulus was presented in extinction showed second-order conditioning comparable to that shown by subjects in a control group that did not receive the extinction procedure. In Experiment 4, subjects approached a second-order stimulus less when sexually satiated than when sexually deprived. These findings suggest that second-order sexual conditioning in quail is mediated by an association of the second-order stimulus with a representation of the unconditioned stimulus. 相似文献
18.
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
19.
Anthony L. Riley David B. Peele Kathy D. Richard Paul J. Kulkosky 《Learning & behavior》1981,9(2):287-290
Animals poisoned following exposure to saccharin subsequently avoided the schedule-induced consumption of saccharin. While this suppression was transient for subjects who had access only to the saccharin solution during the free-food presentations, recovery of schedule-induced saccharin consumption was significantly retarded for subjects who had concurrent access to saccharin and a running wheel. It has been suggested that the transient suppression of schedule-induced polydipsia by conditioned taste aversions results from the pellet-induced tendency to drink within the schedule-induced polydipsia procedure. That access to the running wheel reduces schedule-induced polydipsia in general and prolongs the suppression of schedule-induced polydipsia by taste aversions supports this view. 相似文献
20.
Three experiments were conducted to determine the effectiveness of intravenous (IV) flavor injections in the formation of conditioned taste aversions and in the attenuation of neophobia. In Experiment 1, two groups of rats were permitted to drink either a .1% saccharin solution or tap water followed immediately by IV injections of lithium chloride (LiCl), and two more groups were given IV injections of a 2% saccharin solution followed immediately by IV injections of either LiCl or distilled water. Injected flavor did not serve as an effective CS for the conditioning of an aversion to .1% saccharin. The second experiment employed a two-bottle procedure to detect attenuation of neophobia using the injected-flavor technique. It was found that, whether saccharin had been injected intravenously (2%), injected intraperitoneally (2% IP), or orally consumed (.1%), neophobia for .5% saccharin was attenuated equally relative to controls. CS-US intervals were manipulated in the final experiment such that IP injections of 2% saccharin solution were followed 0–480 min later by IP injections of LiCl. In this case, it was shown that injected flavor (2% saccharin) could act as an effective CS if the US was delayed (optimally about 120 min) and when the test solution was .1% saccharin. The delay gradient found in Experiment 3 was interpreted as a generalization gradient where optimum conditioning was displayed at the point where the concentration of saccharin circulating in the animal at the time of illness onset most closely matched the concentration of the test solution. 相似文献