Evidence for inhibitory associations between the unique elements of two compound flavours

In each of two experiments, rats were pre-exposed to two flavoured solutions, saline-lemon and sucrose-lemon. For group ALT, trials with one solution alternated with trials with the other. Group BLK received all trials with one solution in a block, before any trials with the other. An associative theory suggests that the alternating, but not the blocked, schedule would establish an inhibitory association between sucrose and saline. To provide a retardation test of this inhibition, some animals in each group were then given a single pairing of saline and sucrose, experienced sodium depletion, and were finally tested for their consumption of sucrose. Sodium depletion increased consumption of sucrose more in group BLK than in group ALT. In groups given no saline-sucrose pairing, sodium depletion had only a small effect on sucrose consumption, which was the same in both groups. After multiple pairings of saline and sucrose, sodium depletion had an equally large effect on sucrose consumption in both ALT and BLK groups. These results imply that alternating pre-exposure to two compound solutions does establish an inhibitory association between their unique elements, and thus provide support for an associative theory of perceptual learning.     

Perceptual learning in flavour aversion conditioning

In each of four experiments, rats drank a solution of saline or of lemon and saline shortly before receiving an injection of lithium chloride, and the generalization of the resulting aversion to sucrose or to lemon and sucrose was measured. There was little generalization from saline alone to sucrose alone, and prior exposure to the two solutions had no effect on their discriminability. An aversion conditioned to lemon-saline, however, did generalize to lemon-sucrose, and the extent of this generalization was substantially reduced by prior exposure to the two compound solutions. This perceptual learning effect was partly, but not entirely, attributable to the latent inhibition of the common element, lemon, produced by exposure to the two compounds: animals pre-exposed to lemon alone discriminated between lemon-saline and lemon-sucrose better than animals pre-exposed to saline and sucrose alone; but exposure to the three elements in isolation was not as effective as exposure to the two compound solutions in enhancing their discriminability. The final experiment established that one critical feature of compound pre-exposure is that it involves experience of saline and sucrose in the presence of the same common element. According to an associative theory of perceptual learning, this would result in the establishment of inhibitory associations between saline and sucrose, thus reducing generalization between the two compound solutions.     

Incentive properties of sucrose and saccharin under different deprivation conditions

In Expt 1 it was found that hungry rats developed a 100% preference for 8% sucrose over water in a maze-choice situation, whereas thirsty rats developed no preference. When deprivation conditions for the two groups were reversed the pattern of preference relations also reversed. In a 2nd experiment nondeprived rats developed a preference for either 8% sucrose or 0.2% saccharin over water while thirsty Ss did not develop a preference for either of these over water. The results are discussed in terms of incentive theory.     

Effects of solution viscosity on perceived saltiness and sweetness

Subjects used magnitude estimation to judge the perceived saltiness or sweetness of a series of aqueous solutions containing five suprathreshold concentrations of NaCl or sucrose and thickened with sodium carboxymethylcellulose (CMC). In the first experiment, CMC-H (high viscosity form) was used to thicken a series of sucrose and NaCl solutions to six viscosity levels (1–2,025 centistokes). At the highest viscosity levels, significant decreases occurred in the perceived taste intensity of only the lower concentrations of sucrose and NaCl. A second experiment determined that variations in the quantity of solution sampled from cups did not systematically influence judgments of saltiness when the starting volume was 10 ml. In the third experiment, aqueous solutions containing sucrose or NaCl were thickened with the low (L), medium (M), or high (H) viscosity form of CMC (1–1,296 centistokes). CMC-L-thickened solutions produced little or no suppression of perceived taste intensity, whereas viscous CMC-H solutions produced significant reductions in perceived saltiness and sweetness.     

The effects of feature type in operant serial feature-positive discriminations

In two experiments, rats were trained on two operant serial feature positive discriminations in which one feature was a flavored solution and the second feature was a visual or auditory cue. As in a previous study ([Goddard and Holland, 1996]), transfer of a feature’s control to the target of the other discrimination was not observed when the flavor feature and the reinforcer were flavored sucrose solutions (Experiment 1). The performance of comparison groups showed that this lack of transfer was not due to confounded differences in the event contingencies resulting from having similar stimuli serve as feature and reinforcer. By contrast, in Experiment 2, transfer was observed between visual and flavor features when the flavor feature was unsweetened and the reinforcer was plain sucrose. These results suggest that the lack of transfer in Experiment 1 and in [Goddard and Holland, 1996] study were related to the biological significance or hedonic properties of the sucrose feature.     

The amygdala but not the hippocampus is involved in pattern separation based on reward value

A total of 32 male Long-Evans rats were tested on a modified version of Flaherty, Turovsky, and Krauss's (1994) anticipatory contrast paradigm to assess pattern separation for reward value. Prior to testing, each rat received either a control, a hippocampal, or an amygdala lesion. In the home cage, each rat was allowed to drink a water solution containing 2% sucrose for 3 min followed by a water solution containing 32% sucrose for 3 min. Across 10 days of testing, the rats in each lesion group showed significantly increased anticipatory discriminability as a function of days. To assess the operation of a pattern separation mechanism, each rat was then tested using the same procedure except the 2% solution was followed by a 16% solution for 10 days and then by an 8% solution for 10 days. Control and hippocampal-lesioned rats continued to show high discriminability when the 2% solution was followed by a 16% solution; however, the amygdala-lesioned rats showed low anticipatory discriminability. On trials where the 2% sucrose solution was followed by an 8% sucrose solution, all groups showed low discriminability scores, suggesting that when two reward values are very similar even control animals are not able to separate the reward values in memory. However, the results of a preference task revealed that all groups can perceptually discriminate between a 2% and an 8% sucrose solution. The data suggest that the amygdala but not the hippocampus is involved in the separation of patterns based on reward value.     

Caloric balancing and sucrose intake of hamsters and gerbils

In Experiment 1, hamsters and gerbils were randomly assigned to groups that were given a choice between pairs of sucrose solutions differing in concentration. The groups consisted of a control along with the following pairs: 2% and 6%; 2% and 8%; 2% and 12%; 2% and 18%; 6% and 8%; 6% and 12%; 6% and 18%; 12% and 18%. They were tested for 15 days, and the results indicated that the animals drank more from the cylinder containing the higher concentration. The principle of "least consummatory effort" appeared to be substantiated by these results. In Experiment 2, other hamsters and gerbils were randomly assigned to one of six groups receiving either 0.5%, 2%, 6%, 10%, 14%, or 18% sucrose solution. Analysis of their intake of sucrose and Purina Lab Chow indicated that their total caloric intake was relatively constant, reflecting the fact that an increase of consumption of the solutes in the sucrose solution reduced their intake of the stock diet. The results from both experiments indicated that although the caloric intake of hamsters relative to body weight was greater than that of gerbils, the proportion of total calories taken from sucrose was greater for the latter than for the former.     

网络成瘾者不同情绪状态下的认知加工特征

取在校大学生454人,通过《青少年病理性互联网使用量表》（Adolescent Pathological Internet Use Scale, APIUS),筛查出网络成瘾者31名为实验组,随机抽取样本中其他非成瘾大学生31人为对照组。使用词首－词尾对应三重意义组合图片60个为实验材料,用人物图片为情绪启动刺激,研究被试在不同情绪状态下的认知选择,记录被试选择词组性质和反应时间。研究发现,所有被试对积极词语的选择最多,对消极词语的选择最少,表现出“趋乐避苦”的认知选择倾向;成瘾组被试对积极词语的选择比对照组少,但是对消极词语选择比对照组多。悲伤启动情况下,成瘾组被试对积极词语的选择比对照组少,但是对消极词语的选择则比对照组多。成瘾组被试对积极信息的选择速度比对照组慢,但是对中性信息和消极信息的选择速度则比对照组快。愉快情绪启动下,成瘾组被试的反应时间比对照组短,在悲伤情绪启动下,成瘾组被试的反应时间比对照组长。悲伤情绪启动下,成瘾组被试对积极词语的反应时间比对照组慢,但是对消极词语的反应时间比对照组快。这些研究结果对网络成瘾的治疗有重要的参考价值。     

Development of an ethanol model using social insects: III. Preferences for ethanol solutions

Experiments are designed to assess whether free-flying honey bees have an aversion to an ethanol solution when given a choice between targets containing an ethanol solution in sucrose or sucrose only. Animals given a choice between a 1% ethanol solution and sucrose only show no aversion to the ethanol solution either in acquisition or extinction. Honey bees given a choice between a 5% ethanol solution and sucrose only show no differences in the initial choice of targets but some ees do switch over to the sucrose-only target. Performance during extinction indicates that bees landed on the previously reinforced sucrose-only target more than the target previously containing the 5% ethanol solution. An experiment in which bees were given a single 5%, ethanol target showed that of 20 bees, 11 returned for the entire 12 trials of the experiment. All bees returned at least 6 times to the 5% ethanol target. Additional experiments were run on harnessed foragers in a palatability study of alcoholic beverages consumed by humans. The results of the palatability experiment indicate that in general, bees prefer more sweet drinks with less alcohol.     

Disruption of conditioned taste aversion: evidence that ECS weakens the gustatory engram

Two experiments are reported concerning the neural substrate of conditioned taste aversion (CTA) and the amnesic mechanisms involved when such learning is disrupted by electroconvulsive shock (ECS). Subjects were adult male rats. In the first experiment it is demonstrated that an aversion established to a 2.5% sucrose solution can simulate the learning loss reported in earlier studies which was caused by interpolating ECS between tasting and illness when the aversion was established using a 10% sucrose cue. It is concluded that if ECS acts to disrupt the memory of the taste cue, it possibly reduces it to only about one-quarter of its original strength, a substantial deficit not readily apparent simply from the degree of aversion displayed. In the second experiment, CTAs were established using either a 2.5% sucrose cue or a 10% cue with ECS interpolated during the taste-illness interval. Animals in the two groups were subsequently confronted with a range of sucrose stimuli and their respective aversions were compared. Near identical responses were observed under all conditions tested. These findings are consistent with the theory that ECS disrupts CTA by weakening the gustatory engram.     

Effects of sucrose concentration and goal units on runway behavior in the rat

Experiment 1 investigated the between-S and within-S effects of sucrose concentration (32 and 6%) and number of goal units (equal volumes of sucrose presented in single or multiple goal cups). The goal-unit variable had no effect on behavior under any of several test conditions employed. Within-S effects of sucrose concentration were approximately equal to between-S effects; no contrast effects were found. When 64 and 6% sucrose solutions were used as reinforcers in Experiment 2, a simultaneous, but not a successive, negative contrast effect was found. Results were discussed in terms of possible functional differences between the successive and simultaneous contrast paradigms and between sucrose solutions and solid food as reinforcers.     

Overshadowing of a context aversion by a novel incentive in operant conditioning

Two experiments examined the processes underlying the suppression of instrumental behaviours by lithium in rats, as reported by Meachum (1988 and this issue). Experiment 1 examined whether presenting a novel sucrose solution prior to lithium chloride administration would overshadow aversion learning to either the stimuli of the operant chamber or to familiar food pellets. After lever pressing had been established, and in the absence of responding, animals received free deliveries of a novel sucrose solution, familiar food pellets, or both, or they were exposed to only the cues of the operant chamber, prior to lithium injections. Lever pressing for food pellets was then assessed. It was found that the animals receiving the novel sucrose, either alone or with the familiar food pellets, pressed more for pellets than either the group receiving only food pellets or the group exposed to only the context. In addition, there was no appreciable difference in the response rates between the context-only group and the group that received the familiar food pellets. These outcomes were interpreted in terms of the novel sucrose overshadowing aversion learning to the context. Experiment 2 investigated whether in fact aversive contextual conditioning could be obtained using the present parameters. This was accomplished by directly manipulating the contexts. In this experiment animals were trained to lever press in two distinctive contexts. Subsequently, one context was paired with the novel sucrose, and the second was experienced in the absence of reinforcement prior to toxicosis. During a subsequent non-reinforced test it was found that responding in the context paired with the novel sucrose was considerably higher than responding in the context that was experienced alone. These findings stand in contrast to the taste-mediated contextual potentiation observed when a consumatory response is used to assess aversive contextual conditioning.     

Effects of Devil′s Advocacy and Dialectical Inquiry on Individuals versus Groups

There is a long history of research that has investigated the effects of cognitive conflict on group and individual decision making. No study has simultaneously compared the effects of two techniques, devil′s advocacy and dialectical inquiry, on the performance of individuals versus groups. In this paper, we report the results of a laboratory experiment that makes this comparison. Artificial groups (groups formed by pooling individuals working independently) obtained an overall lower-quality solution for a case analysis problem than intact groups. However, there were no performance differences between intact groups and the performance of the best member of artificial groups. When artificial and intact groups were examined together, those given the devil′s advocacy treatment produced higher-quality solutions than those given the dialectical inquiry treatment and a simpler expert-based approach involving no conflict. Intact groups given the devil′s advocacy treatment produced higher-quality solutions than those given the expert treatment. Artificial groups given devil′s advocacy produced higher-quality solutions than those given the expert or dialectical inquiry treatment. Overall, the results suggest that the devil′s advocacy treatment has a slightly greater advantage over the dialectical inquiry with individuals than with groups.     

The effect of normative models on individual and group choice

Studied the effect of a normative model (maximization of expected value) upon group and individual choice. 109 MBA students in a Lain square research design chose between two alternatives differing in expected value and in range of outcomes. Group choices were significantly (p < .05) closer to those predicted by the normative model than were individual choices. This difference was not due only to information about the presence and applicability of the normative model but rather it was due to the persuasiveness of the model in a group as a cogent and correct solution to the choice dilemma. Task instructions emphasizing the rewards from risk taking produced significantly more choices (p < .05) of the riskier alternative, particularly by individuals as opposed to groups, than did instructions emphasizing the penalties of risk taking. ‘Risky’ and ‘conservative’ shifts in choice between groups and individuals were explicable through knowledge of the influence of the normative model in individual and group choice.     

Test of a Level of Aspiration model of group decision making: Non-obvious group preference reversal due to an irrelevant alternative

We conducted two experiments that investigated a non-obvious prediction of a Level of Aspiration (LOA) model of group decision making. In both experiments, groups chose among three alternatives, A, B, and C, with C always being least preferred by all of the group members. In each experiment, by manipulating the nature of alternative C, we created two conditions differing in whether only A or only B was acceptable to all members. In support of the LOA model, groups tended to choose the alternative acceptable to all members, even when (Experiment 2) a majority of members most preferred a different alternative. Implications of the results for the LOA model are discussed in the context of social choice theory.     

Positive contrast obtained in reacquisition following interpolation of nonreinforced or partially reinforced trials

Two experiments investigated the effects of shifting from either nonreinforcement or partial reinforcement (PRF) to continuous reinforcement conditions (CRF). In the first experiment, three groups of rats were given food reinforcement under CRF conditions in a runway followed by regular extinction trials (RE), extinction trials where Ss were delayed for 30 sec before entering the empty goal box (DE), or CRF trials where Ss were delayed for 30 sec before entering the baited goal box (DF). Then all Ss were run on the delayed reinforcement condition (DF). In the final delayed reinforcement condition, group DE ran significantly faster than group DF, reflecting positive contrast. In the second experiment, four groups of rats were trained in a runway to receive either 4% or 18% sucrose reinforcers under either PRF or CRF conditions. Then all Ss were transferred to a Skinner box and bar presses were continuously reinforced, with each S continuing to receive the same sucrose concentration as before. The former PRF Ss, regardless of the reinforcer, bar pressed at a significantly higher rate in the Skinner box than the former CRF Ss. The evidence seemed to favor the view that the effectiveness of a reinforcer is not an absolute, unchanging quantity but rather depends on the historical context in which the reinforcer occurs.     

Preference as a function of the correlation between stimuli and reinforcement outcomes

Pigeons' preferences for stimuli that were to varying degrees correlated with outcomes were studied in two experiments using a concurrent-chain procedure. The pigeons chose between two terminal links, each ending with food reinforcement and with blackout on half of the trials. In the first experiment, one terminal link (nonpredictive or unreliable link) provided stimuli completely uncorrelated with the outcomes while the other terminal link (predictive or reliable link) provided stimuli that were, to varying degrees, correlated with these outcomes. All pigeons showed increasing preferences for the predictive link as the reliability of the stimuli in that link increased. In the second experiment, stimuli in both terminal links were differentially correlated with the outcomes. The pigeons again preferred the more reliably correlated terminal link. The relation between these results and the delay-reduction hypothesis and conditioned reinforcement account is noted. The behavioral value of predictive stimuli may lie in their permitting the organism to more effectively apportion its time between interim activities and terminal responses.     

Secrets and Disclosures: How Young Children Handle Secrets

The authors examined the influence of content and verbal cues on young children's understanding of secret information and of its disclosure. Participants were 209 5- and 6-year-old children in an experiment where a puppet, named Zinc, was the protagonist. Children were asked to whom Zinc would disclose a list of pieces of information, some of which are considered secrets. Children could choose between Zinc's friend, a nonfriend, both friend and nonfriend, or nobody. Participants were divided in 2 experiment groups: In the first group a prior verbal cue was given to the participants that some information might be secret, whereas in the second group no prior cue was presented. Results showed that young children, similar to older individuals, differentiated between secrets and nonsecrets partly on the basis of content, and chose to withhold secrets more than nonsecrets or to share secrets more with friends than with nonfriends, following the restrictive self-disclosure pattern. In contrast, young children did not withhold nonsecret information, but they shared it with friends and nonfriends. However, when given verbal cues regarding potential secrecy of the information, young children chose more restrictive disclosure patterns for all types of content.     

Simultaneous contrast: evidence from licking microstructure and cross-solution comparisons

The microstructure of rats' licking responses was analyzed to investigate both "classic" simultaneous contrast (e.g., Flaherty & Largen, 1975) and a novel discrete-trial contrast procedure where access to an 8% test solution of sucrose was preceded by a sample of either 2%, 8%, or 32% sucrose (Experiments 1 and 2, respectively). Consumption of a given concentration of sucrose was higher when consumed alongside a low rather than high concentration comparison solution (positive contrast) and consumption of a given concentration of sucrose was lower when consumed alongside a high rather than a low concentration comparison solution (negative contrast). Furthermore, positive contrast increased the size of lick clusters while negative contrast decreased the size of lick clusters. Lick cluster size has a positive monotonic relationship with the concentration of palatable solutions and so positive and negative contrasts produced changes in lick cluster size that were analogous to raising or lowering the concentration of the test solution respectively. Experiment 3 utilized the discrete-trial procedure and compared contrast between two solutions of the same type (sucrose-sucrose or maltodextrin-maltodextrin) or contrast across solutions (sucrose-maltodextrin or maltodextrin-sucrose). Contrast effects on consumption were present, but reduced in size, in the cross-solution conditions. Moreover, lick cluster sizes were not affected at all by cross-solution contrasts as they were by same-solution contrasts. These results are consistent with the idea that simultaneous contrast effects depend, at least partially, on sensory mechanisms.     

Effect of various discriminative stimuli on choice behavior in male siamese fighting fish (Betta splendens)

The current experiment was an exploratory study empirically comparing three discrimination methodologies proposed for use in choice preparations with food rewards. Subjects were thirty-five, healthy, adult male Siamese fighting fish (Betta splendens). Subjects were randomly assigned to one of three discrimination groups: a Direction group (using left or right as discriminative stimuli), a Color group (using red or green as discriminative stimuli), and a Bubble group (using the presence or absence of air bubbles as discriminative stimuli). For all three discrimination groups, subjects chose between one or three food pellets in a submerged T-maze. The results from the experiment indicated a statistically significant preference for the three pellets of food over one pellet of food only for the Bubble group. Of particular note is the effect size and observed power obtained for the Bubble group, which was the only group which supported a reasonably powerful test for discrimination, given a sample size of 12 subjects and 0.94 effect size.