Do common ravens (<Emphasis Type="Italic">Corvus corax</Emphasis>) rely on human or conspecific gaze cues to detect hidden food?

The ability of non-human animals to use experimenter-given cues in object-choice tasks has recently gained interest. In such experiments, the location of hidden food is indicated by an experimenter, e.g. by gazing, pointing or touching. Whereas dogs apparently outperform all other species so far tested, apes and monkeys have problems in using such cues. Since only mammalian species have been tested, information is lacking about the evolutionary origin of these abilities. We here present the first data on object-choice tasks conducted with an avian species, the common raven. Ravens are highly competitive scavengers, possessing sophisticated cognitive skills in protecting their food caches and pilfering others’ caches. We conducted three experiments, exploring (i) which kind of cues ravens use for choosing a certain object, (ii) whether ravens use humans’ gaze for detecting hidden food and (iii) whether ravens would find hidden food in the presence of an informed conspecific who potentially provides gaze cues. Our results indicate that ravens reliably respond to humans’ touching of an object, but they hardly use point and gaze cues for their choices. Likewise, they do not perform above chance level in the presence of an informed conspecific. These findings mirror those obtained for primates and suggest that, although ravens may be aware of the gaze direction of humans and conspecifics, they apparently do not rely on this information to detect hidden food.     

Differential responses to con- and allospecific visual cues in juvenile ravens (Corvus corax): the ontogeny of gaze following and social predictions

Animal Cognition - Gaze following refers to the ability to co-orient with others’ gaze directions. Ontogenetic studies on gaze following in animals have predominantly used human experimenters...     

Non-tool-using rooks, <Emphasis Type="Italic">Corvus frugilegus</Emphasis>, solve the trap-tube problem

The trap-tube problem is used to assess whether an individual is able to foresee the outcome of its actions. To solve the task, an animal must use a tool to push a piece of food out of a tube, which has a trap along its length. An animal may learn to avoid the trap through a rule based on associative processes, e.g. using the distance of trap or food as a cue, or by understanding relations between cause and effect. This task has been used to test physical cognition in a number of tool-using species, but never a non-tool-user. We developed an experimental design that enabled us to test non-tool-using rooks, Corvus frugilegus. Our modification of the task removed the cognitive requirements of active tool use but still allowed us to test whether rooks can solve the trap-tube problem, and if so how. Additionally, we developed two new control tasks to determine whether rooks were able to transfer knowledge to similar, but novel problems, thus revealing more about the mechanisms involved in solving the task. We found that three out of seven rooks solved the modified trap-tube problem task, showing that the ability to solve the trap-tube problem is not restricted to tool-using animals. We found no evidence that the birds solved the task using an understanding of its causal properties, given that none of the birds passed the novel transfer tasks.     

Social context,interpersonal network,and identity dynamics: A social psychological case study of terrorist recidivism

The existing literature on jihadist terrorism has extensively documented the importance of networks, yet the interpersonal element of the networks and how this links to the social identity dynamics of a mujahid have been scarcely explored. It also is still unclear how specific social contexts such as prison, neighbourhood, and home may play a role in the link between interpersonal networks and social identity dynamics. Drawing insights from the social identity perspective, this article examines the relationships between social context, interpersonal networks, and identity dynamics of a mujahid based on a single case of terrorist recidivism in Indonesia. Our analyses showed how transitions across social contexts were related to the subject's opportunities and constraints for the participation in different interpersonal networks that influenced the process of identity negotiation as a mujahid versus alternative identities of family member and belonging to a neighbourhood. It is argued that analysis of the dynamics of a mujahid's identity in local social contexts are an important part of assessing risks of their recidivism.     

The good,the bad and the ugly thing to do when sharing information: Revealing,concealing and lying depend on social motivation,distribution and importance of information

Research on information sharing in group decision-making has widely assumed a cooperative context and focused on the exchange of shared or unshared information in the hidden profile paradigm (36 and 37), neglecting the role of information importance. We argue that information sharing is a mixed-motive conflict setting that gives rise to motivated strategic behavior. We introduce a research paradigm that combines aspects of the traditional information sampling paradigm with aspects of a public good dilemma: the information pooling game. In three experiments, we show that information sharing is strategic behavior that depends on people’s pro-social or pro-self motivation, and that people consider information sharedness and information importance when deciding whether to reveal, withhold, or falsify their private or public information. Pro-social individuals were consistently found to honestly reveal their private and important information, while selfish individuals strategically concealed or even lied about their private and important information.     

Cultural knowledge,category label,and social connections: Components of cultural identity in the global,multicultural context

Cultural identity refers to the psychological connection between an individual's self and a culture. In this paper, we identify three components that make up an individual's cultural identity – cultural knowledge, category label, and social connections. The cultural knowledge component connects an individual with a culture through the individual's direct endorsement of what are widely known to be the culture's central characteristics. The category label component connects an individual with a culture through the individual's depersonalized membership in a cultural collective. The social connections component connects an individual with a culture through networks of specific social relationships. The three components are conceptually distinct, and yet may have interconnections in influencing the development of cultural identity. We examine the implications of the three components on cultural identification processes in the context of multiculturalism and global cultural contact.     

Manipulating stereotype rating tasks: understanding questionnaire context effects on measures of attitudes,social identity and stereotypes

Context effects in the questionnaire measurement of national stereotypes have been demonstrated in many studies since the early pioneering work of Katz and Braly (1933). More recently, self-categorization approaches (e.g. Oakes, Haslam and Turner, 1994) have been used to explain context effects, with the suggestion that variation in stereotype content can be conceptualized as variation in the comparative meaning of categories, as specified by the meta-contrast principle. However, the methodological consequences of stereotype context effects for survey responding remain poorly understood. Using an experimental questionnaire manipulation, the current study demonstrates empirically that varying the stereotype rating task presented to respondents can have knock-on effects on responding in other questionnaire modules—in this case, modules exploring attitudes to European integration and national and European social identities. It is suggested that stereotype rating tasks might activate some social identities whilst inhibiting the activation of others, and that these effects might be affected by the level of abstraction of the social identities concerned. © 1998 John Wiley & Sons, Ltd.     

Bullying and victimisation in school children: the role of social identity, problem-solving style, and family and school context

The relationship between social identity, family and school context, problem-solving style, self-esteem, health behaviour, psychological distress, and victimisation, was explored in a quasi-experimental survey of 461 children aged between 11 and 15 years old. There was a high prevalence of victimisation (29%) in the group and 44% of those victimised scored above the clinical cut-off on the GHQ. Victims exhibited higher levels of psychological distress, lower self-esteem, more unhealthy behaviours, less support from parents and teachers, poorer problem-solving styles, and lower perceived social identity. Girls had a higher prevalence of victimisation than boys. The best predictors of victimisation were sex, family situation, social identity and problem-solving style. Some implications for interventions are discussed.

(M,R)-Systems and their Realizations

Robert Rosen’s (M,R)-systems are a class of relational models that define organisms. The realization of relational models plays a central role in his study of life, itself. Biology becomes identified with the class of material realizations of a certain kind of relational organization, exhibited in (M,R)-systems. In this paper I describe several realizations of (M,R)-systems, and in particular alternate realizations of the replication component.     

Tufted capuchins (<Emphasis Type="Italic">Cebus apella</Emphasis>) attribute value to foods and tools during voluntary exchanges with humans

This research examined exchange and value attribution in tufted capuchin monkeys (Cebus apella). We presented subjects with opportunities to obtain various foods and a tool from an experimenter in exchange for the foods or tool in the subjects' possession. The times elapsed before the first chow biscuits were expelled and/or an exchange took place were recorded as the dependent measures. Laboratory chow biscuits, grapes, apples, and a metal bolt (a tool used to probe for syrup) were used as experimental stimuli. The subjects demonstrated the ability to recognize that exchanges could occur when an experimenter was present with a desirable food. Results indicate that subjects exhibited significant variation in their willingness to barter based upon the types of foods that were both in their possession and presented by the experimenter. Subjects more readily traded chow biscuits for fruit, and more readily traded apples for grapes than grapes for apples. During the exchange of tools and food, the subjects preferred the following in descending order when the probing apparatus was baited with sweet syrup: grapes, metal bolts, and chow biscuits. However when the apparatus was not baited, the values changed to the following in descending order: grapes, chow, and metal bolts. These results indicate that tufted capuchins recognize opportunities to exchange and engage in a simple barter system whereby low-valued foods are readily traded for more highly valued food. Furthermore, these capuchins demonstrate that their value for a tool changes depending upon its utility.     

Foraging and associative learning of visual signals in a parasitic wasp

To cope with environmental variability, animals should gather and use information to reduce uncertainty. In insect parasitoids, associative learning has been widely documented in the context of host foraging. However, despite its potential adaptive value, the insect food searching strategy and cues used to search are poorly understood. In this study, we examined the ability of hymenopteran Venturia canescens females to associate food to a visual cue. To broaden the scope of our results, experiments were performed with both arrhenotokous (sexual) and thelytokous (asexual) individuals. The wasps showed innate attraction for yellow and orange stimuli when presented versus blue stimuli. When trained to associate a food reward with one of the attractive colours (orange), they significantly moved from a distance towards the colour previously associated with food. The choice of the innately preferred colour (yellow) was not modified by associative learning. In the context of food foraging, this study is the first to show associative learning using visual stimuli in a parasitoid and active choice of this colour. This ability gives new insights concerning potential food sources for V. canescens in the field, since flowers are sugar sources, which emit colour signals.     

Open questions related to the problem of Birkhoff and Maltsev

The Birkhoff-Maltsev problem asks for a characterization of those lattices each of which is isomorphic to the lattice L(K) of all subquasivarieties for some quasivariety K of algebraic systems. The current status of this problem, which is still open, is discussed. Various unsolved questions that are related to the Birkhoff-Maltsev problem are also considered, including ones that stem from the theory of propositional logics.Special issue of Studia Logica: Algebraic Theory of Quasivarieties Presented by Ryszard Wójcicki     

Effects of social context, reinforcer probability, and reinforcer magnitude on humans' choices to compete or not to compete.

In the first two experiments, subjects' choices to earn points (exchangeable for money) either by competing with a fictitious opponent or by not competing were studied. Buskist, Barry, Morgan, and Rossi's (1984) competitive fixed-interval schedule was modified to include a second response option, a noncompetitive fixed-interval schedule. After choosing to enter either option, the opportunity for reinforcers became available after the fixed-interval's duration had elapsed. Under the no-competition condition, points were always available after the interval had elapsed. Under the competition condition, points were available based on a predetermined probability of delivery. Experiments 1 and 2 examined how reinforcer probabilities and reinforcer magnitudes affected subjects' choices to compete. Several general conclusions can be made about the results: (a) Strong preferences to compete were observed at high and moderate reinforcer probabilities; (b) competing was observed even at very low reinforcer probabilities; (c) response rates were always higher in the competition component than in the no-competition component; and (d) response rates and choices to compete were insensitive to reinforcer-magnitude manipulations. In Experiment 3, the social context of this choice schedule was removed to determine whether the high levels of competing observed in the first two experiments were due to a response preference engendered by the social context provided by the experimenters through instructions. In contrast to the first two experiments, these subjects preferred the 60-s fixed-interval schedule (formerly the no-competition option), indicating that the instructions themselves were responsible for the preference to compete. This choice paradigm may be useful to future researchers interested in the effects of other independent variables (e.g., drugs, social context, instructions) on competitive behavior.     

Gender Differences in the Construction of Spirituality, Work, Learning, and Community by Baalei Teshuvah

This paper explores the question, “How do Jewish men and women who have become Orthodox (baalei teshuvah) compare in their constructions of spirituality, work, learning, religious practices, and community?” It is based on a qualitative research study that included interviews with 48 baalei teshuvah (24 men, 24 women), two focus groups, and ten key informant interviews. Participants were from the East Coast of the USA. We found the women more affirmative about their spirituality and feelings about community; men identified with these experiences but not the terminology. The men gave more attention to work and to their struggles integrating work and religion. The women expressed excitement about learning whereas the men conveyed self-consciousness over their language and learning deficiencies.     

Model structure adequacy analysis: selecting models on the basis of their ability to answer scientific questions

Models carry the meaning of science. This puts a tremendous burden on the process of model selection. In general practice, models are selected on the basis of their relative goodness of fit to data penalized by model complexity. However, this may not be the most effective approach for selecting models to answer a specific scientific question because model fit is sensitive to all aspects of a model, not just those relevant to the question. Model Structural Adequacy analysis is proposed as a means to select models based on their ability to answer specific scientific questions given the current understanding of the relevant aspects of the real world.     

School track and ethnic classroom composition relate to the mainstream identity of adolescents with immigrant background in Germany,but not their ethnic identity

Although developing a cultural identity is a core task for adolescents from immigrant families and the school is a highly important context in adolescence, to date, few studies have examined whether adolescents with particular cultural identities cluster in certain school contexts. Using data from a representative German sample including 7702 secondary school students of immigrant background from 1643 classrooms, we examined how the attended school track and four aspects of ethnic classroom composition relate to adolescents' cultural identity (i.e., their ethnic identity and mainstream identity). Two-level structural equation models indicated that students' ethnic identity was not systematically associated with the attended school track and the ethnic composition of the classroom. However, attending the academic school track, a classroom with a low proportion of classmates with immigrant background and frequently using German with classmates related positively to mainstream identity. Ethnic diversity and proportion of co-ethnics in class did not relate to mainstream identification. Our findings suggest that the ethnic identity of adolescents with an immigrant background in Germany is largely independent from the different socialisation contexts related to school tracks and the ethnic classroom composition. Yet, students' with a strong mainstream identity cluster in certain school contexts.     

Subcellular interactions between parallel fibre and climbing fibre signals in purkinje cells predict sensitivity of classical conditioning to interstimulus interval

Classical conditioning of the nictitating membrane response requires a specific temporal interval between conditioned stimulus and unconditioned stimulus, and produces an incrase in Protein Kinase C (PKC) activation in Purkinje cells. To evaluate whether biochemical interactions within the Purkinje cell may explain the temporal sensitivity, a model of PKC activation byCa ²⁺, diacylglycerol (DAG), and arachidonic acid (AA) is developed.Ca ²⁺ elevation is due to CF stimulation and IP3 inducedCa ²⁺ release (IICR). DAG andIP ₃ result from PF stimulation, while AA results from phospholipase A2 (PLA ₂). Simulations predict increased PKC activation when PF stimulation precedes CF stimulation by 0.1 to 3 s. The sensitivity of IICR to the temporal relation between PF and CF stimulation, together with the buffering system of Purkinje cells, significantly contribute to the temporal sensitivity.     

Opportunity,opportunism, and progress:Kairos in the rhetoric of technology

As the principle of timing or opportunity,kairos serves both as a powerful theme within technological discourse and as an analytical concept that explains some of the suasory force by which such discourse maintains itself and its position in our culture. This essay makes a case for a rhetoric of technology that is distinct from the rhetoric of science and illustrates the value of the classical vocabulary for understanding contemporary rhetoric. This case is made by examining images and models of technological change that underlie and justify the thematizations ofkairos that appear in so much technological discourse and by exploring the phenomenon of technological forecasting, in which the characterization and construction of moments in the present are crucial to the projection of the future. One example of forecasting is examined in detail: the Japanese Fifth Generation computer project, which illustrates the twin themes of opportunity and threat.     

Length, formats, neighbours, hemispheres, and the processing of words presented laterally or at fixation

It has long been known that the number of letters in a word has more of an effect on recognition speed and accuracy in the left visual field (LVF) than in the right visual field (RVF) provided that the word is presented in a standard, horizontal format. After considering the basis of the length by visual field interaction two further differences between the visual fields/hemispheres are discussed: (a) the greater impact of format distortion (including case alternation) in the RVF than in the LVF and (b) the greater facilitation of lexical decision by orthographic neighbourhood size (N) in the LVF than in the RVF. In the context of split fovea accounts of word recognition, evidence is summarised which indicates that the processing of words presented at fixation is affected by the number of letters to the left of fixation but not by the number of letters to the right and by the number of orthographic neighbours activated by letters to the left of fixation but not by the number of orthographic neighbours activated by letters to the right of fixation. A model of word recognition is presented which incorporates the notion that the left hemisphere has sole access to a mode of word recognition that involves parallel access from letter forms to the visual input lexicon, is disrupted by format distortion, and does not employ top-down support of the letter level by the word level.     

The quiet of the fierce barracuda: masculinity and aggression in Pohnpei, Micronesia

This paper provides historical background on youth violence for the understudied indigenous Micronesian culture of Pohnpei. Aggression has long been of high cultural value for men in Pohnpei. Masculinity was assessed on a man's power and authority (manaman), as generally indicated by his possession of a ranked title within the chiefly hierarchy. For the very highest ones, a man's title was awarded on the basis of matrilineal genealogical connections; for all other titles, more weight was placed on individual achievements (with the help of relatives, undertaken for the chiefs) in the most competitive realms of society—bravery in warfare and prestations (i.e., the offering of valuable gifts that are due to people of high status) at feasts. Masculinity was also assessed in terms of a man's heterosexual prowess. A man's successes in these realms were based on his possession of special knowledge, skills, and other characteristics—but typically, these were carefully secluded from public notice and dramatically revealed only on special occasions. One Pohnpeian proverb states, “The quiet of the fierce barracuda.” Like a barracuda, a man lies quietly in the water, waiting for his prey to appear; when it does, he rises swiftly and surely to the attack.Many changes to Pohnpeian culture have resulted from nearly two centuries of various foreign activities on the island. This paper explores the changes in indigenous masculinity and aggression during early foreign contact by whalers, traders, beachcombers, and missionaries who used Pohnpei as a major port of call; over four successive colonial regimes in Micronesia that had headquarters in Pohnpei; during Japanese militarization of the island in World War II; and in the American rule that quickly followed. The indigenous Pohnpeian cultural notions of masculinity and aggression, with modifications over these centuries of contact, are ones that Pohnpeians carry with them in diaspora, primarily to the United States, especially in the more developed Pacific Islands located nearby, such as Guam and Hawai'i.