Diet sampling by wild Norway rats offered several unfamiliar foods

The present experiment was undertaken to examine directly the diet sampling behavior of wild Norway rats (Rattus norvegicus) faced with a choice among familiar and unfamiliar foods. First-generation, laboratory-reared wild Norway rats ate from four food cups. Three of the food cups were in unfamiliar locations and contained unfamiliar foods. The remaining food cup was in a familiar location and contained a familiar food. Subjects in a control group were offered the familiar food in all four locations. We found (1) that subjects in experimental and control conditions took equal amounts of time to first visit food cups in unfamiliar locations, (2) that subjects in the experimental condition (those with access to unfamiliar foods) ate at unfamiliar locations at a slower rate than did subjects in the control condition (those with access only to familiar food), (3) that subjects in the experimental condition were no more likely than subjects in the control condition to eat at one unfamiliar location at a time, and (4) that following a bout of eating at an unfamiliar food cup, subjects in the experimental condition waited no longer than subjects in the control condition before eating from a different unfamiliar food cup. We interpreted these data as indicating that although wild Norway rats are hesitant to eat unfamiliar foods, once they begin to eat such foods, they do not sample among them so as to facilitate identification of any toxin present.     

Familiarity and relatedness: Effects on social learning about foods by Norway rats and Mongolian gerbils

In recent experiments in which the social influences on feeding in Mongolian gerbils were investigated, observer gerbils acquired food preferences from conspecific demonstrators only if the demonstrators and observers were either related or familiar. Even then, the effects of demonstrator gerbils on observers’ food choices lasted less than 24 h. In similar experiments with Norway rats, the familiarity/relatedness of demonstrators and observers had little effect on social learning, and the demonstrators’ influence on observers’ food choices lasted many days. We examined the causes of these differences and found that, after observer gerbils interacted with either unfamiliar or familiar conspecific demonstrators that had been fed using procedures typically used to feed demonstrator rats, they showed long-lasting social learning about foods, whereas observer rats interacting with conspecific demonstrators that had been fed as demonstrator gerbils normally are fed showed effects of familiarity/relatedness to demonstrators on their social learning about foods. Procedural differences, rather than species differences, seem to be responsible for reported inconsistencies in social learning about foods by rats and gerbils.     

Further evidence that Norway rats do not socially transmit learned aversions to toxic baits

Three experiments were undertaken to examine the effects of interactions with demonstrator rats made ill by injection of lithium chloride (LiCl) on the later food choices of their observers. We found that (1) observer rats that had been taught an aversion to an unfamiliar diet exhibited a substantial reduction of that aversion after interacting with poisoned demonstrators that had eaten the diet to which the observers had learned an aversion, (2) exposure of an observer rat to poisoned demonstrator rats that had eaten a diet interfered with later acquisition by the observer of an aversion to the diet that the poisoned demonstrators had eaten, and (3) after interacting with poisoned demonstrators that had eaten one of two diets, observers that ate both diets and were then made ill formed an aversion to whichever diet their respective, poisoned demonstrators had not eaten. The present experiments, like previous studies both in our laboratory and elsewhere, failed to provide any evidence that naive observer rats will learn to avoid a food as a result of interacting with demonstrator rats that had eaten the food and exhibit symptoms of toxicosis. To the contrary, observer rats in the present experiments exhibited an enhanced preference for foods eaten by sick demonstrators.     

Social learning and social transmission of foraging information in Norway rats (Rattus norvegicus)

Adult male Norway rats were tested in a first experiment to see whether foraging efficiency could be improved by social learning. Observers were placed in one of four conditions in which they were paired with demonstrators that either had or had not been previously trained to dig for buried carrot pieces, and in which the demonstrators either did or did not have carrot buried in the experimental enclosure. Observers in the group with trained demonstrators that did have carrot pieces buried in the experimental area during the observation period subsequently unearthed more buried carrot, did so more rapidly, and were generally more active than were the observers in the other three groups. In a second experiment, chains of transmission were established by allowing each observer to act as a demonstrator for the next naive observer. Enhanced levels of digging behavior were maintained across eight transmission episodes in three transmission groups relative to a no-transmission control group, the performance levels becoming stable after five transmission episodes at a level significantly above that of the control group. The study demonstrates that social learning and transmission mechanisms exist which might result in the diffusion of certain patterns of behavior through populations of Norway rats.     

Social influence on avoidance of dangerous stimuli by rats

Three experiments were conducted to determine whether a naive observer rat would avoid contact with a shock prod after watching a demonstrator rat contact, be shocked by, and defensively bury the prod. We found that observer rats took longer to contact prods that had delivered a shock to and been buried by a demonstrator rat than to contact prods that had not delivered shock and had not been buried. However, observer rats contacted prods buried by an unseen demonstrator rat or by an unseen experimenter with the same latencies as those for prods they had seen deliver shock to and be buried by a demonstrator rat. In large enclosures, subjects took 1–2 h longer to contact buried prods than to contact unburied prods. We conclude that alteration of the physical environment by individuals receiving noxious stimulation can significantly reduce the probability that conspecifics will contact the noxious stimulus. Observational learning per se, however, need not be involved.     

Social transmission of information about multiflavored foods

We fed demonstrator rats diets made by adding three, four, or five different flavorants to powdered Purina Rat Chow. We then allowed each of these demonstrator rats to interact with a naive observer rat for 30 min. We found that (1) observers exhibited enhanced preferences for many of the individual flavorants in the multiflavored diets that their respective demonstrators had eaten and (2) the probability of an observer exhibiting enhanced preference for an individual flavorant in its demonstrator’s diet decreased as the number of flavorants in that diet increased. In Experiment 2, the individual members of pairs of subjects were each fed one of two different four-flavored diets. The subjects in each pair interacted for 30 min, then each chose between two single-flavored diets. One of these single-flavored diets contained a flavorant in the four-flavored food that a subject had itself eaten; the other single-flavored diet contained a flavorant in the four-flavored diet that a subject’s partner had eaten. The subjects showed enhanced preferences for six of eight flavorants in the four-flavored diets that their respective partners had eaten.     

Social and asocial cues about new food: Cue reliability influences intake in rats

Dietary generalists often treat new foods with caution and may rely on social cues to identify new foods that are safe to eat. However, not all generalists show the same degree of caution, nor do they all rely on social cues to the same extent. The cue reliability approach (CRA) attempts to account for this variation by quantifying the costs and benefits of sampling a new food for the first time. The experiments reported here tested predictions of the CRA, and the results suggested that rats eat more new food when asocial cues predict that new foods will prove more profitable than familiar foods. The experimental results also suggested that rats are more likely to seek out social cues when asocial cues are unreliable.     

Necessary and sufficient conditions for communication of diet preferences by Norway rats

Rats that (1) either ate a small sample of one or two foods (Diet A or Diet B) or interacted with a demonstrator that had eaten either Diet A or Diet B, (2) ate both Diets A and B in succession, and (3) were made ill preferred whichever of the two foods they or their respective demonstrators had eaten. Although eating a food and interacting with a demonstrator that had eaten that food were each sufficient to enhance preference for the food, eating particles of food clinging to the fur of a demonstrator was not necessary for enhancement of preference for the food that a demonstrator ate. Subjects exposed to demonstrators they could not physically contact still exhibited enhanced preference for the food that their demonstrator had eaten. The data were discussed as indicating that although smelling a diet, eating a diet, and interacting with a demonstrator that had eaten a diet can each enhance preference for that diet, it cannot be inferred that eating a food, smelling a food, and interacting with a demonstrator that has eaten a food each affect diet preference via the same process.     

Social influences on children's development of relational thinking during small-group discussions

This microgenetic study strived to understand instantaneous peer influences on the moment-by-moment and session-by-session development of relational thinking within and across dialogic small-group discussions using an approach called Collaborative Reasoning. An analysis encompassing 32,511 turns for speaking during 176 discussions indicated that peer support and refutation influenced the development of relational thinking within (micro-level) and across (macro-level) discussions, and was mediated by friendship and peer status. Support was mainly mediated by friends and children with high status. Observing reciprocated friends' supportive talk encouraged students to generate confirmational relational thinking in the next turn for speaking. Refutation was mainly mediated by children with high status. Quiet students generated less refutation. The study documents the proximal effects of peer status and friendship on the social and cognitive dynamics of collaborative discussions.     

Open-field behavior of wild and domestic Norway rats

The open-field behavior of wild and domestic Norway rats was compared in 15-min tests administered over 5 successive days. Wild rats exhibited more ambulation, jumping, grooming, and time inactive than domestic rats and spent more time along the arena wall. Within- and between-trial changes in behavior were generally greater for wild rats. Factor analyses revealed major loadings on factors identified as “locomotor behavior” and “grooming.” Support was obtained for the hypothesis that domestication has raised the threshold for avoidance-escape behavior in response to a novel environment.     

The influences of guiding cues on motor skill autonomy in rats

How does the effectiveness of guiding cues influence the development of motor skill autonomy? We utilized two sets of guiding cues (lights vs. reversed-lights conditions) that differed in their effectiveness to control a left–right leverpress sequence in rats. We separately measured the development of stimulus control by panel lights on guiding-cues trials and the development of stimulus control by practice cues on no-cue probe trials within the same sessions. Accuracy in the presence of the guiding cues was acquired faster in the lights condition than in the reversed-lights condition, but subjects in the reversed-lights condition were more able to complete the skill autonomously than those in the lights condition. Throughout acquisition, control by guiding cues and practice cues developed at the same rate in the reversed-lights condition, but control by practice cues (autonomy) developed at a slower rate than did control by guiding cues in the lights condition. At the end of training, subjects that had been exposed to the reversed-lights condition displayed higher levels of autonomy than did those exposed to the lights condition. The less effective guiding cue (reversed-lights) produced greater levels of autonomy than did the more effective cue (lights), even though control by this guiding cue developed more slowly. Thus, guiding your child by the hand too much may reduce his or her ability to complete the task independently. We discuss the similarity to prompt dependence in children with learning disabilities and transfer of stimulus control.     

Social and economic influences on graduation rates from higher education in Australia

This paper presents an examination of national survey data on the graduation rates of young people who enter higher education in Australia. Two cohorts of young people were surveyed – those born in 1961 and those born in 1965. Of interest is the influence of gender and of selected social and economic background characteristics on graduation rates. The results for both cohorts provide further evidence of the gains made by young females during the 1980s in terms of educational participation and attainment. The results for the first cohort show also there were some signs of lower graduation rates being associated with socioeconomic disadvantage, at least as indicated by parent'`s occupational status and family wealth. For the second cohort, however, there was little evidence of any effect in the same direction. This suggests that attempts to deal with equity which have focussed on performance within higher education have either been quite effective or might be better directed towards the selection processes which lead to higher education.     

The influence of artificial paths and landmarks on the foraging behavior of Norway rats (Rattus norvegicus)

In two experiments, we explored how the foraging behavior of Norway rats was influenced by different arrangements of artificial paths and vertical landmarks. The rats used the paths successively less for orienting to food in treatments in which paths led to food but were crooked, in which paths led only halfway to food, and in which paths were misaligned with respect to food. The arrangement of paths influenced the rats’ rate of energy intake in the beginning of the experiment, whereas the arrangement of beacons did not. With experience, the rats employed different orientation strategies in the presence of different arrangements of paths or beacons, and, by the final 4 days, all groups achieved statistically indistinguishable net rates of return. The rates of energy intake were similar because the rats in different treatments traveled similar distances per session, despite differing arrangements of paths and landmarks.     

School matters: how context influences the identification of different types of special educational needs

Despite dramatic changes in Irish special education policy during the last decade, there is little understanding of the factors influencing how special educational needs (SEN) are identified and whether identification varies across different school contexts. International research has tended to focus on how individual child characteristics influence SEN identification. Less attention has been given to other factors such as teacher characteristics or school social mix. Using data from the nine-year-old cohort of the Growing Up in Ireland study, this article examines which children are most likely to be identified with different SEN types taking into account student social background characteristics, teacher characteristics and school social mix. Findings show that children attending highly disadvantaged school contexts are far more likely to be identified with behavioural problems and less likely to be identified with learning disabilities than children with similar characteristics attending other schools. It seems that ‘behavioural’ issues take precedence over learning difficulties in these schools pointing to a culture of care/containment rather than academic progress.     

Transfer of information concerning distant foods in rats: A robust phenomenon

Following interaction with a “demonstrator” rat, an “observer” rat prefers that diet eaten by its demonstrator prior to their interaction (Galef & Wigmore, 1983). The present series of studies demonstrates that such demonstrator influence on observer diet preference can be found in: (1) first-generation laboratory bred wild rats as well as domesticated rats, (2) food-deprived as well as nondeprived observers, (3) unfamiliar as well as familiar demonstrator-observer pairs, (4) both 21-day-old and adult observers, and (5) rats selecting fluids as well as solids for ingestion. These data indicate that the social transmission of information concerning distant diets is a general and robust phenomenon, observable under a wide variety of experimental conditions.     

价值认同与当今学校社会责任感教育的构建

随着全球化的发展,认同危机日益显现,其核心表现为价值认同的困境.价值认同困境已经成为当今学校社会责任感教育不能回避的时代挑战.事实上,价值认同与社会责任感的养成具有密切的关系,前者为后者提供重要的观念基础和情感催化剂.因此,当今的社会责任感教育应该建立在发展基本价值认同的基础上.这既有助于缓解价值认同困境的挑战,推动学生主动内化社会责任,生发责任认同感,也将使社会责任感教育深化为围绕“社会责任感”的价值教育.     

褐家鼠种群生态特征的研究

根据对广东省境内褐家鼠２个自然种群的生态特征分析,发现褐家鼠分成５个年龄组别．除幼年鼠组外,其它年龄组的体重,秋季高于冬季．成年Ⅰ、成年Ⅱ和老年组是褐家鼠的主要繁殖群体．秋季的种群繁殖力明显高于冬季．秋季的种群,雌性鼠多,雄性鼠少;冬季的种群则雌性鼠少,雄性鼠多     

Social cognitive influences on self-regulated learning: The impact of action-control beliefs and academic goals on achievement-related outcomes

The present study extended Elliot and Church's (1997) model of approach and avoidance motivation to a sample of 120 middle school children (Grades 5–7). It was predicted that academic goals (Performance-Approach, Performance-Avoidance, and Mastery) would mediate the relationship between action-control beliefs (Agency for Ability, Effort, Luck, Others, and Control Expectancy Beliefs) and achievement-related outcomes (Intrinsic Motivation, Test Anxiety, and Academic Achievement). Path analyses revealed that academic goals, (a) mediated the relationship between action-control beliefs and intrinsic motivation; (b) partially mediated the relationship between action-control beliefs and test anxiety; and (c) did not mediate the relationship between action-control beliefs and academic achievement. These findings suggest that the strength of the mediational relationship varied as a function of achievement-related outcome. Furthermore, analyses revealed that minority student differences in achievement were mediated by individual differences in action-control beliefs, specifically, beliefs regarding personal ability and likelihood of academic success. These results suggest that minority student variability in academic achievement may be a function of commensurate differences in action-control beliefs. Implications for intervention and a general social cognitive model of self-regulated learning are discussed.     

Establishment of dominance in domestic Norway rats: Effects of the degree of captivity and social experience

Learning & Behavior - The effect of the level of captivity and prior social experience on the establishment of dominance was examined in 16 colonies of albino rats. Males were assigned to one...