共查询到20条相似文献，搜索用时 46 毫秒
1.
In four experiments, the once daily availability of saccharin (.15%) preceded the availability of sucrose (32% or 2%). Experiment 1 showed that the intake of saccharin was reduced when it preceded 32% sucrose but not when it preceded 2% sucrose, as compared with saccharin-alone conditions. Experiment 2 showed that less saccharin was consumed when the saccharin preceded sucrose by 5 min than when there was a 30-min intersolution interval. Experiment 3 replicated this finding and showed that the presentation of the two solutions through the same or different access holes in the apparatus was not relevant to the result. Experiment 4 showed that there was an inverse relationship between saccharin intake and the length of the intersolution interval in the range of 1 to 30 min. These data were interpreted to indicate that the animals learn the predictive relationship between the saccharin and sucrose solutions and that the intake of the saccharin is reduced by an anticipatory contrast mechanism—a mechanism that may have restricted temporal parameters. 相似文献
2.
Charles F. Flaherty Patricia S. Grigson Cynthia Coppotelli Colin Mitchell 《Learning & behavior》1996,24(1):68-81
Intake of a 0.15% saccharin solution was suppressed when it was followed by a 32% sucrose solution in brief daily pairings. With equal access durations to the two solutions, intervals of intermediate duration (2 or 3 min) produced a larger contrast than more extreme intervals (1 or 10 min). There was no evidence of inhibition of delay with the 10-min interval (Experiments 1A and 1B). When access times were asymmetrical, longer access time to the first solution reduced contrast, whereas longer access time to the second solution enhanced contrast (Experiment 2). Contrast was greater when the two solutions were presented at consistent and separate spatial locations than when location was changed randomly or when both solutions were presented in sequence at the same location. However, a degree of contrast occurred in all conditions (Experiment 3). Experiment 4, conducted with the solutions in opposite arms of a T-maze, showed that anticipatory approach to the location correlated with the 32% sucrose solution developed prior to lick suppression on the saccharin solution. However, within daily sessions, there was a reliable increase in contrast without correlated changes in anticipatory-approach behavior. Access-time effects were attributed to altered reward values, whereas spatial-separation effects suggest that goal-directed responses contribute to, but do not cause, anticipatory contrast. 相似文献
3.
Contrast in consummatory behavior occurs readily when a less preferred substance follows a preferred substance. A previous experiment indicated that contrast in consummatory behavior may also develop when a less preferred substance precedes a preferred substance in brief daily exposures. In the present experiment, the same animals sometimes received 0.15% saccharin followed, 15 sec later, by 32% sucrose (.15–32) and sometimes received 0.15% saccharin followed by the same 0.15% saccharin solution (.15-.15). One solution pair was given each day, and the two conditions, .15–32 and .15-.15, occurred in alternation across days. The two different solution conditions were correlated with different cues. Saccharin intake from the first tube was lower when the second tube contained 32% sucrose than when it contained .15% saccharin, both in original discrimination training and following a reversal of the cue-solution pairings. These results support the conclusion that contrast in this situation is based on the anticipation of the impending 32% sucrose each day, rather than on a retrograde comparison with the 32% sucrose received the previous day. These data are considered in terms of Pavlovian conditioning outcomes when the CS is a stimulus with hedonic value. 相似文献
4.
Previous experiments have shown that the intake of a 0.15% saccharin solution is suppressed if saccharin access is followed by access to 32 % sucrose in brief daily pairings. The present experiments found that: (1) the degree of suppression was not altered when no time elapsed between presentation of the two solutions each day (15 sec had been the minimum in previous experiments and was used as the control in this experiment); (2) the degree of suppression was not altered by chlordiazepoxide (6, 12, or 20 mg/kg), although the drug had large appetite-stimulating effects; (3) suppression was not influenced by amphetamine (0.25 or 0.50 mg/kg); and (4) contrast could be established or eliminated, even after extended training, by manipulating the sequences of solutions presented (saccharin-saccharin or saccharin-sucrose). The results were interpreted in terms of a contrast effect based on the learned anticipation of a preferred substance. The chlordiazepoxide data suggest that this contrast is different from successive negative contrast, and the intersolution interval data suggest that the occurrence of contrast rather than a reinforcement effect is not due to a time gap between presentations of the two solutions. 相似文献
5.
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
6.
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
7.
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
8.
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
9.
Rats were selectively bred for high versus low saccharin ingestion, a putative measure of enhanced stress and emotionality (Dess, 1991). In Experiment 1, third-generation Occidental high-saccharin (HiS) and low-saccharin (LoS) rats were tested for saccharin ingestion and emotionality. The saccharin test confirmed that the lines differed on the selection phenotype. In addition, LoS rats were more emotional, as evidenced by longer emergence latencies and more defecation in a modified open-field test. In Experiment 2, LoS rats had lower quinine preference scores and drank saccharin-adulterated glucose less avidly. These outcomes are reminiscent of the behavior shown by inescapably shocked rats. Unlike helpless rats, however, LoS rats drank less avidly during a dilute sucrose test, an effect more reminiscent of chronic mild stress. The lines did not differ reliably on intake of concentrated glucose or Polycose, even when the latter was mixed with saccharin. In Experiment 3, LoS rats preferred saccharin less strongly than did HiS rats at concentrations of 0.05% to 0.7% and had an aversion to a 1.0% solution. In Experiment 4, LoS rats were affected more by shock, as assessed by stress-induced anorexia. These and other recent findings support the notion of shared mechanisms for taste, emotionality, and stress vulnerability. 相似文献
10.
Luís Gonzalo De la Casa Auxiliadora Mena Juán Carlos Ruiz-Salas Esperanza Quintero Mauricio R. Papini 《Learning & behavior》2018,46(1):49-59
Three experiments explored the link between reward shifts and latent inhibition (LI). Using consummatory procedures, rewards were either downshifted from 32% to 4% sucrose (Experiments 1–2), or upshifted from 4% to 32% sucrose (Experiment 3). In both cases, appropriate unshifted controls were also included. LI was implemented in terms of fear conditioning involving a single tone-shock pairing after extensive tone-only preexposure. Nonpreexposed controls were also included. Experiment 1 demonstrated a typical LI effect (i.e., disruption of fear conditioning after preexposure to the tone) in animals previously exposed only to 4% sucrose. However, the LI effect was eliminated by preexposure to a 32%-to-4% sucrose devaluation. Experiment 2 replicated this effect when the LI protocol was administered immediately after the reward devaluation event. However, LI was restored when preexposure was administered after a 60-min retention interval. Finally, Experiment 3 showed that a reward upshift did not affect LI. These results point to a significant role of negative emotion related to reward devaluation in the enhancement of stimulus processing despite extensive nonreinforced preexposure experience. 相似文献
11.
Lynn J. Hammond 《Learning & behavior》1995,23(3):349-356
Three experiments were conducted to demonstrate that the place where an organism has been, before the organism is moved to a place with aversive consequences, can also become aversive through classical conditioning. In Experiment 1, two groups of 8 mice were exposed to three different contexts in succession, with a single shock occurring in the third context. The distal context was a putative 3-min conditioned stimulus (CS) for freezing; the second context was a delay manipulation; and the unconditioned stimulus (US) occurred in the proximal context. The group delayed for 15 sec showed significantly more freezing to the distal CS context than did the group delayed for 3 h. In a second experiment, conditioning to the distal context was demonstrated with a discrimination procedure for 8 more mice by using two different distal contexts as CS+ and CS? for the proximal context with shock. On CS+ days, 3 min of exposure to the distal context was followed within 5 sec by placement in the proximal box where shock occurred, whereas on CS? days, exposure to a second distal context was followed immediately by return to the home cage. Very strong differences in freezing between the CS+ and CS? distal contexts were found in all 8 mice after 14 days of conditioning. In a third experiment, the discriminative procedure was repeated for 9 more mice, with two changes. More objective stabilometertype activity measures were substituted for observed freezing, and, in addition to the CS+ and CS? distal context trials, each mouse was also exposed to a third discriminative distal context, which was followed by 15 min in a delay chamber followed by shock in the proximal context. This discrimination procedure with the activity suppression measure again resulted in significant differences between the contexts. The CS+ context and the context followed by a 15-min delay did not differ, but both of them differed from the CS? context. 相似文献
12.
Four experiments examined whether or not spontaneous recovery could occur after extinction in the conditioned taste-aversion paradigm. After three extinction trials, spontaneous recovery was obtained over an 18-day retention interval (Experiments 1, 2, and 3). The effect was not due to changes in the unconditioned preference for saccharin over the retention interval (Experiment 2) or to an increase in a nonextinguished aversion over time, as indicated by tests with both the original, nonextinguished aversion (Experiment 1) and with a weaker one (Experiment 3). Spontaneous recovery was not obtained when extinction was overtrained (eight trials) and a 49-day retention interval was used (Experiment 4). However, saccharin intake at asymptote reached the level of baseline water intake, and not the highly preferred level shown by never-conditioned controls. Results of all four experiments suggest that extinction does not return an averted taste to the status of an unconditioned one. 相似文献
13.
Anthony L. Riley Richard L. Hyson Cory S. Baker Paul J. Kulkosky 《Learning & behavior》1980,8(2):211-217
In Experiment 1, rats poisoned following schedule-induced saccharin consumption showed a moderate reduction in the schedule-induced consumption of saccharin. With repeated poisoning, schedule-induced saccharin polydipsia was markedly reduced. Acquisition of conditioned aversion under the schedule-induced procedure was significantly slower than acquisition under water deprivation. In addition, recovery of consumption of the previously poisoned solution during extinction was more rapid under schedule-induced polydipsia. Experiment 2 revealed that schedule-induced polydipsia was less sensitive to suppression by conditioned aversions than a prandial drinking condition in which subjects were equally food deprived but were given a mass feeding instead of spaced pellet deliveries, suggesting that the relative insensitivity of schedule-induced polydipsia to conditioned taste aversions is not simply a function of different levels of food deprivation. This relative insensitivity is offered as a partial basis for the occurrence and maintenance of schedule-induced alcohol polydipsia. 相似文献
14.
Discrimination and memory for video films of women performing different activities was investigated in 5.5 month-old infants. In Experiment 1, infants (N = 24) were familiarized to the faces of one of three women performing one of three repetitive activities (blowing bubbles, brushing hair, and brushing teeth). Overall, results indicated discrimination and memory for the actions but not the faces after both a 1-min and a 7-week delay. Memory was demonstrated by a visual preference for the novel actions after the 1-min delay and for the familiar actions after the 7-week delay, replicating prior findings that preferences shift as a function of retention time. Experiment 2 (N = 12) demonstrated discrimination and memory for the faces when infants were presented in static poses at the 1-min delay, but not the 7-week delay. In Experiment 3 (N = 18), discrimination of the actions was replicated, but no discrimination among the objects embedded in the actions (hairbrush, bubble wand, toothbrush) was found. These findings demonstrate the attentional salience of actions over faces in dynamic events to 5.5 month-olds. They highlight the disparity between results generated from moving versus static displays in infancy research and emphasize the importance of using dynamic events as a basis for generalizing about perception and memory for events in the real world. 相似文献
15.
Elizabeth D. Capaldi David E. Myers David H. Campbell Joan Denise Sheffer 《Learning & behavior》1983,11(1):107-115
In five experiments, rats’ preference for a flavor was greater if the flavor had previously been consumed under low rather than high deprivation. This preference was conditioned in as few as three flavor-deprivation pairings (Experiment 1), and persisted through 28 test days, half under each deprivation level (Experiment 2). Rats never preferred the flavor associated with high deprivation even when calories were increased by giving 40 ml of 8% sucrose or when caloric density was increased to the equivalent of 20% sucrose. The preference for the low-deprivation flavor was greater when saccharin solutions were used rather than sucrose solutions, but the preference did emerge when sucrose solutions were used as testing proceeded and when a lower concentration of sucrose was used. We suggest that these preferences may be a result of flavor-taste associations rather than associations between flavors and postingestive consequences, and that the taste of the solutions under low deprivation is preferred to the taste under high deprivation. 相似文献
16.
Fred P. Valle 《Learning & behavior》1990,18(4):387-392
For 2 h prior to their daily meal of Purina Chow, rats (which were 14% below ad-lib weight levels) had access to a sucrose solution. For half (Group 16-4), the solution was alternated daily between 18% and 4%; for the other half (Group 4-4), the solution was always 4%. On 18% days, Group 16-4 consumed significantly more calories and gained significantly more weight than did Group 4-4, because of a greater consumption of sucrose calories (Purina intake was similar for the two groups). On 4% days, however, Group 16-4 consumed both significantly fewer sucrose calories and significantly fewer Purina calories than did Group 4-4. These two contrast effects resulted in a 17% shortfall in total caloric intake for Group 16-4 on 4% days. As a consequence, Group 16-4 showed a significant drop in body weight, compared to Group 4-4, on 4% days. A second experiment was carried out to investigate whether the contrast-induced reduction in Purina intake shown by Group 16-4 on 4% days would be eliminated if (1) a 30-min interval separated sucrose ingestion from Purina ingestion, or (2) a 25-min interval plus 5-mmn exposure to 16% sucrose separated ingestion of 4% sucrose from Purina ingestion. Purina intake was still suppressed in Group 16-4 under both conditions. 相似文献
17.
It has been reported previously that rats prefer a flavor they consumed under high deprivation to a flavor they consumed under low deprivation (Revusky, 1967). Here it was found that this preference occurs only if nutritive solutions are used and the flavors are given preceding and following eating. If flavors are given separately from the daily feeding, rats prefer the flavor given under low deprivation, whether or not a nutritive solution is used (Experiment 3). If flavors are given before and after the daily feeding, rats prefer the flavor they had under high deprivation (before feeding) more if sucrose solutions are used than if saccharin solutions are used and more on a high-deprivation test than on a low-deprivation test (Experiments 1 and 2). It was concluded that the “incentive value” of consumption is not necessarily higher under high deprivation than under low deprivation. The preference for the low-deprivation flavor obtained here may reflect a greater proportional rewarding effect of consumption under low deprivation or may reflect an aversion to the flavor consumed under high deprivation. Perhaps a small taste of flavor under high deprivation initiates responses of digestion that are unsatisfied and thus aversive, and the more so the higher the deprivation level. 相似文献
18.
Rats injected with lithium chloride after ingesting familiar food pellets presented in textured metal sleeves learned aversions to the sleeved food. In a choice between sleeved and unsleeved food, the aversions were evident following conditioning with toxicosis delayed as long as 120 min after exposure to the sleeved food (Experiment 1). Texture-specific aversions resulted from procedures in which rats were exposed to food in both rough- and smooth-textured sleeves but were injected with lithium only in conjunction with one of the textures (Experiments 2–4). This differential aversion learning occurred when lithium treatment was delayed 30 min after exposure to the sleeved food (Experiments 3 and 4) and was equally evident in rats conditioned and tested in total darkness or in normal room-level illumination (Experiment 4). However, differential texture aversion learning was not observed with 90- or 300-min delayed toxicosis (Experiment 3). The present experiments highlight the importance of tactile cues in the poison-avoidance learning of species that handle their food during the course of ingestion. 相似文献
19.
Following ingestion of either water (Experiment 1) or saccharin (Experiment 2), experimental groups of rats were poisoned with lithium chloride and acquired an aversion to the ingested fluid. This aversion gradually extinguished and, in both experiments, was not reacquired when fluid intake was again followed by poisoning. These results are in marked contrast to usual findings of very rapid relearning following extinction with conditioning preparations other than taste-aversion learning. 相似文献
20.
In three experiments, water-deprived rats were preexposed to a novel saccharin solution. The neophobic response to this flavor was then assessed in a choice test involving saccharin and water, administered either immediately or 24 h after preexposure. Subjects displayed a significantly greater preference for saccharin at the 24-h test than at the immediate test (Experiments 2 and 3). This “incubation” effect was eliminated if the subjects were more water-deprived at the delayed test than at the immediate test (Experiment 1), and enhanced if the amount of saccharin consumed during preexposure was increased (Experiment 3). Possible ways in which current theories of habituation might be amended in order to accommodate this finding are discussed. 相似文献