Apparent disinhibition of successive but not of simultaneous negative contrast

In a series of three experiments, rats shifted from a 32% to a 4% sucrose solution, after 10 days’ exposure to the 32% solution, exhibited a negative contrast effect in lick rate. In each experiment, shifted rats that received a novel stimulus (tone) during the postshift period exhibited a higher lick rate (smaller contrast effect) than shifted subjects not receiving the tone. This increase in lick rate resembles Pavlovian disinhibition and is interpreted as supporting an inhibitory view of successive negative contrast effects. Control conditions included in Experiments 2 and 3 favored the disinhibition interpretation of the effect of the tone, as opposed to a rate-dependency hypothesis or to the nonspecific energization of behavior. In Experiments 4–6, the tone was introduced coincident with the occurrence of a simultaneous negative contrast effect. Rather than disinhibition, a decrease in licking occurred. These results were discussed in terms of differences between successive and simultaneous contrast.     

Extended exposure to environmental cues,but not to sucrose,reduces sucrose cue reactivity in rats

In the present study, we examined the effects of extinction of sucrose-predictive contextual cues and/or sucrose satiation on the expression of sucrose cue reactivity in a rat model of relapse. Context extinction was imposed by housing rats in their home cage or in the operant conditioning chamber for 17 h prior to testing. For sucrose satiation, rats were allowed unlimited access to water or sucrose for 17 h prior to testing. Cue reactivity was assessed after either one (Day 1) or 30 (Day 30) days of forced abstinence from sucrose self-administration. An abstinence-dependent increase in sucrose cue reactivity was observed in all conditions (“incubation of craving”). Context extinction dramatically reduced lever responding on both Day 1 and Day 30. Sucrose satiation had no significant effect on cue reactivity in any condition. These results demonstrate that the context in which self-administration occurs maintains a powerful influence over cue reactivity, even after extended forced abstinence. In contrast, the primary reinforcer has little control over cue reactivity. These findings highlight the important role of conditioned contextual cues in driving relapse behavior.     

Repeated successive contrast in consummatory behavior with repeated shifts in sucrose concentration

Contrast in consummatory behavior was investigated following repeated shifts from 32% to 4% sucrose. In Experiment 1, contrast in licking and in open-field measures of activity occurred following the second and third downshifts. In Experiments 2a and 2b, equivalent contrast effects occurred following the first and second downshifts in sucrose. In Experiment 3, negative contrast remained unabated following nine downshifts in animals shifted between 32% and 4% sucrose on alternate days. Similar results were found for five downshifts in animals shifted every 2 days. In both of these latter conditions, positive contrast occurred over the first few shifts and was then lost as the 32% control group reached asymptote. These data show that repeated negative contrast effects in consummatory behavior are robust and enduring and occur under several different sets of experimental parameters. The results are discussed in terms of reinforcement level and emotional interpretations of contrast effects, and the possibility was suggested that the causal mechanism of contrast changes with repeated shifts.     

Positive and negative contrast effects obtained following shifts in liquid sucrose reward in thirsty rats

In a repeated shifts experiment four independent groups of thirsty rats received the following treatments: LSLS, LLLS, SSLS, and SSSS, with each letter denoting the magnitude (large or small) of sucrose reward received in each of the four phases of the experiment. While no negative contrast effect (NCE) was obtained in Phase 2, a very reliable positive contrast effect (PCE) was found in Phase 3. Moreover, a significant NCE was obtained in Phase 4. The results were explained in terms of the relative rather than absolute effects of reinforcement.     

Social interactions in male gerbils,Meriones unguiculatus: Ultrasounds and open-field behavior

Relationships among ultrasonic vocalizations and several other behaviors (aggression, locomotion, ventral-scent-gland marking, sniffing, and autogrooming) were examined during single 15-min interactions within 12 different pairs of adult male gerbils. Behaviors were assessed before and after social dominance was established within each pair. Ultrasound emissions were associated with fight severity (r=?.66), locomotion was associated with scent marking (r=.86) and with autogrooming (r=.68), and scent marking was associated with sniffing (r=.67). Dominant and subordinate animals showed different patterns of behavior both before and after dominance was established. Primary predictors of intrapair dominance were priority and latency of scent marking. After dominance was established, gerbils with the higher ranks showed significantly greater locomotion, sniffing, and autogrooming.     

Bidirectional contrast,matching, and power functions obtained in sucrose consumption by rats

Rats were given alternating 1-min access to two tubes containing sucrose solutions that varied in concentraton (32% vs. 2%, 32% vs. 4%, 32% vs. 8%, and 32% vs. 16%). Lick rate for 32% sucrose was higher when the alternative tube contained a lower concentration solution than when both tubes contained 32% (a positive-contrast effect), and lick rate for the lower concentration solution (2%, 4%, 8%, or 16%) was lower when the alternative tube contained 32% than when both tubes contained the lower concentration solution (negative contrast effect). Proportion of licks made for 32% under contrast conditions tended to match the proportion of concentration available from that tube. Regression analysis of the ratio of licks made to the two tubes under contrast conditions as a function of ratio of concentrations available indicated a good fit to a power function with an exponent of 1.13, within the range of those typically found in human magnitude estimation studies of relative sweetness.     

Partial reward,the negative contrast effect,and incentive averaging

A total of 169 rats, distributed across six experiments, received training in a straight runway with a 5-min intertrial interval. A variety of shifts in reward schedules, to and from partial reward, were employed to assess the effects of partial reward on the successive negative contrast effect. The results were seen as supportive of an incentive averaging approach to partial reinforcement.     

《素问》"生而勿杀、予而勿夺、赏而勿罚"语义辨析

《素问·四气调神大论》是古代医家在“天人相应”观指导下,根据四季气候变化对人体的影响,提出如何顺应四时阴阳变化规律而养生防病的一篇极为重要的文献。正确地译释该文,对继承、发掘前人的学术思想,拓展与丰富养生保健的方法与措施十分重要。但对原文中“生而勿杀、予而勿夺、赏而勿罚”句的语义,自唐、明、清代至今,历代注家见解不一。或言其意指应“顺时待物”;或言其意为“勿伐天时”;或言其意是指人不同的“神志活动”;或言其意仅为春生之气的“形容词”等等。本文从原文的主旨、语言逻辑、语法规律、词义注释、中医理论等方面提出了自己全新的看法。认为“生、予、赏”三句是古人对如何顺应春生之气养生防病的具体要求;并由此提出春季养生防病应重在调肝护肝和顺时序治疗肝病的新观点。     

The relations among child negative interactive behavior,child temperament,and maternal behavior

Negative behavior toward the mother during toddlerhood might be a marker of increased risk for maladjustment. The aim of the present study was to examine the possible antecedents of toddler boys’ negative behavior observed in interaction with the mother: child temperament, and maternal behavior toward the child. We studied the moderating and mediating role of two dimensions of maternal behavior, sensitivity and intrusiveness, in the relationship between children's temperamental traits (frustration, soothability and activity level), on the one hand, and child negative behavior, on the other hand. The sample consisted of 112 mother–son dyads observed when the child was 17 months old. A temperament questionnaire was completed by the mothers. Child negative interactive behavior, maternal sensitivity and intrusiveness were observed at home during a 13-min play session. Maternal sensitivity was negatively related to child negative interactive behavior regardless of child temperament. Maternal intrusiveness, however, moderated the relation between activity level and negative behavior, i.e., children with high activity level showed higher levels of negative behavior especially when the mother was highly intrusive. Furthermore, maternal intrusiveness acted as a mediator in the relation between soothability and negative behavior, i.e., low soothability was linked to higher maternal intrusiveness, which in turn was associated with higher negative behavior.     

Observing birth and placentophagia affects placentophagia but not maternal behavior of virgin rats

To determine whether observing components of periparturitional behavior affects the manifestation of those behaviors in virgin rats, virgins selected for nonplacentophagia and for the absence of spontaneous maternal behavior toward pups were exposed to stimulus rats that were giving birth, eating donor placenta, or eating lab chow. During observations, subjects could either eat donor placenta or just see and smell it. The subjects were tested subsequently for placentophagia and for the rate of onset of pup-induced maternal behavior. The results indicated that: (1) access to placenta in the presence of other rats led to placentophagia; (2) when such placentophagia occurred in conjunction with exposure to other rats that were giving birth or eating donor placenta, the subjects became permanent placentophages (otherwise, the subjects reverted and did not eat on subsequent placentophagia tests); (3) none of the observation conditions, regardless of the availability of placenta during observation, affected the maternal sensitization latency. The results are discussed in terms of social facilitation, exposure learning, and desensitization to exteroceptive stimuli.     

Dyslexic children show deficits in implicit sequence learning,but not in explicit sequence learning or contextual cueing

Dyslexia is a specific learning disability characterized by difficulties with accurate and/or fluent word recognition and by poor spelling abilities. The absence of other high level cognitive deficits in the dyslexic population has led some authors to propose that non-strategical processes like implicit learning could be impaired in this population. Most studies have addressed this issue by using sequence learning tasks, but so far the results have not been conclusive. We test this hypothesis by comparing the performance of dyslexic children and good readers in both implicit and explicit versions of the sequence learning task, as well as in another implicit learning task not involving sequential information. The results showed that dyslexic children failed to learn the sequence when they were not informed about its presence (implicit condition). In contrast, they learned without significant differences in relation to the good readers group when they were encouraged to discover the sequence and to use it in order to improve their performance (explicit condition). Moreover, we observed that this implicit learning deficit was not extended to other forms of non-sequential, implicit learning such as contextual cueing. In this case, both groups showed similar implicit learning about the information provided by the visual context. These results help to clarify previous contradictory data, and they are discussed in relation to how the implicit sequence learning deficit could contribute to the understanding of dyslexia.     

Cognitive regulation,not behavior regulation,predicts learning

Although inquiry learning has increasingly been a topic of empirical research, there has been little investigation of individual differences in this regard. What makes some students more effective inquiry learners than others? We examined two kinds of self-regulation – cognitive regulation and behavior regulation – as possible predictors of individual differences in middle-school students’ inquiry learning performance. Across two studies, one involving middle-class students (n = 135) and one involving students from a lower socioeconomic status underachieving population (n = 21), results were consistent. Cognitive regulation, but not behavior regulation, was associated with more successful inquiry learning. We discuss implications for the role of regulatory processes in inquiry learning and, more broadly, for education.     

训练不是事件,而是流程

自从数字学习从2000年开始蓬勃发展后,数字内容与教材市场并不如预期的快速成长,反倒是经过几年课程e化经验后,大家对传统的训练模式的学习效果产生怀疑.美国企业数字学习大师Jay Cross就提出几个突破的新口号:"训练不是个事件(event),而是流程(process)";"学习不在于内容,也不在于结构,而是锻炼成神经回路(forging neural link)的过程".     

Letter knowledge precipitates phoneme segmentation,but not phoneme invariance

There is a wealth of evidence linking letter knowledge and phoneme awareness, but there is little research examining the nature of this relationship. This article aims to elucidate this relationship by considering the links between letter knowledge and two sub‐skills of phoneme awareness: phoneme segmentation and phoneme invariance. Two studies are reported. The first study consisted of an eight‐month longitudinal study with 56 pre‐literate children. No child within this group was successful on any phoneme awareness task unless they knew at least one letter. Letter knowledge was also a significant predictor of later phoneme completion and deletion. The hypothesis that letter knowledge is an important precursor for phoneme awareness was then investigated in a small‐scale intervention study with ten children. These children were taught letters and their phoneme awareness was monitored. It was found that letter knowledge was specifically related to the development of phoneme segmentation in pre‐literate children. Possible reasons for this finding are discussed.     

Rotational stress influences sensitized,but not habituated,exploratory behaviors in the woodlouse, <Emphasis Type="Italic">Porcellio scaber</Emphasis>

Terrestrial isopods (or woodlice), like the members of the other arthropod taxa, have a sophisticated nervous system that makes them sensitive to specific environmental factors. They can search for survival-related opportunities (e.g., approaching food sources or avoiding sunny areas). Two experiments examined how rotational stress could influence the propensity of common woodlice, Porcellio scaber to exhibit survival-related behaviors such as traveling and rearing up in a hostile environment. Experiment 1 assessed the behaviors of stressed and nonstressed woodlice exposed to a familiar or a novel environment without rewards. Experiment 2 assessed the effects of stress in woodlice given a free choice between a familiar and a novel environment without rewards. In the nonstressed individuals, the results showed a decrease in locomotor activity (habituation) and an increase in the time spent rearing up (sensitization) on the arena’s walls over time. In the stressed individuals, repeated rotation had a detrimental effect on the time spent rearing up, but locomotion was decreased only in the stressed individuals that were not preexposed to the test environment beforehand. In addition, immobilization periods—as a plausible indicator of stress—were longer in the absence of preexposure. It is suggested that preexposure had some antistress protective effects on habituated but not on sensitized, exploratory behaviors in woodlice.     

Retrieval practice after multiple context changes,but not long retention intervals,reduces the impact of a final context change on instrumental behavior

Recent evidence from this laboratory suggests that a context switch after operant learning consistently results in a decrement in responding. One way to reduce this decrement is to train the response in multiple contexts. One interpretation of this result, rooted in stimulus sampling theory, is that conditioning of a greater number of common stimulus elements arising from more contexts causes better generalization to new contexts. An alternative explanation is that each change of context causes more effortful retrieval, and practice involving effortful retrieval results in learning that is better able to transfer to new situations. The current experiments were designed to differentiate between these two explanations for the first time in an animal learning and memory task. Experiment 1 demonstrated that the detrimental impact of a context change on an instrumental nose-poking response can be reduced by training the response in multiple contexts. Experiment 2 then found that a training procedure which inserted extended retention intervals between successive training sessions did not reduce the detrimental impact of a final context change. This occurred even though the inserted retention intervals had a detrimental impact on responding (and, thus, presumably retrieval) similar to the effect that context switches had in Experiment 1. Together, the results suggest that effortful retrieval practice may not be sufficient to reduce the negative impact of a context change on instrumental behavior. A common elements explanation which supposes that physical and temporal contextual cues do not overlap may account for the findings more readily.