Asymmetric learning transfer between imagined viewer- and object-rotations: Evidence of a hierarchical organization of spatial reference frames

Neural resources subserving spatial processing in either egocentric or allocentric reference frames are, at least partly, dissociated. However, it is unclear whether these two types of representations are independent or whether they interact. We investigated this question using a learning transfer paradigm. The experiment and material were designed so that they could be used in a clinical setting. Here, we tested healthy subjects in an imagined viewer-rotation task and an imagined object-rotation task. The order of the tasks was counterbalanced across subjects. The results showed that subjects who did the viewer-rotation task first had fewer errors and shorter latencies of response in the object-rotation task, whereas subjects who did the object-rotation task first had little if any advantage in the viewer-rotation task. In other words, the results revealed an asymmetric learning transfer between tasks, which suggests that spatial representations are hierarchically organized. Specifically, the results indicate that the viewer-rotation task engaged allocentric representations and egocentric representations, whereas the object-rotation task engaged only egocentric representations.     

Spontaneous number representation in mosquitofish

While there is convincing evidence that preverbal human infants and non-human primates can spontaneously represent number, considerable debate surrounds the possibility that such capacity is also present in other animals. Fish show a remarkable ability to discriminate between different numbers of social companions. Previous work has demonstrated that in fish the same set of signature limits that characterize non-verbal numerical systems in primates is present but yet to provide any demonstration that fish can really represent number rather than basing their discrimination on continuous attributes that co-vary with number. In the present work, using the method of ‘item by item’ presentation, we provide the first evidence that fish are capable of selecting the larger group of social companions relying exclusively on numerical information. In our tests subjects could choose between one large and one small group of companions when permitted to see only one fish at a time. Fish were successful when both small (3 vs. 2) and large numbers (8 vs. 4) were involved and their performance was not affected by the density of the fish or by the overall space occupied by the group.     

The juvenile transition: A developmental switch point in human life history

This paper presents a new perspective on the transition from early to middle childhood (i.e., human juvenility), investigated in an integrative evolutionary framework. Juvenility is a crucial life history stage, when social learning and interaction with peers become central developmental functions; here it is argued that the “juvenile transition” is a developmental switch point in the human life history, when both sex-related and individual differences in reproductive strategies are expressed after the assessment period provided by early childhood. Adrenarche, the secretion of adrenal androgens starting at the beginning of middle childhood, is proposed as the endocrine mechanism mediating the juvenile transition. It is argued that, in connection with the stress system, adrenal androgens enable adaptive plasticity in the development of reproductive strategies through integration of environmental and genetic factors. Finally, evidence is reviewed of both sex-related and individual differences arising during the juvenile transition, in the domains of attachment and aggression. Juvenility plays a central role in the ontogeny of behavior and personality; this paper contributes to defining its place within an integrated model of human development.     

Learning reward expectations in honeybees

The aim of this study was to test whether honeybees develop reward expectations. In our experiment, bees first learned to associate colors with a sugar reward in a setting closely resembling a natural foraging situation. We then evaluated whether and how the sequence of the animals’ experiences with different reward magnitudes changed their later behavior in the absence of reinforcement and within an otherwise similar context. We found that the bees that had experienced increasing reward magnitudes during training assigned more time to flower inspection 24 and 48 h after training. Our design and behavioral measurements allowed us to uncouple the signal learning and the nutritional aspects of foraging from the effects of subjective reward values. We thus found that the animals behaved differently neither because they had more strongly associated the related predicting signals nor because they were fed more or faster. Our results document for the first time that honeybees develop long-term expectations of reward; these expectations can guide their foraging behavior after a relatively long pause and in the absence of reinforcement, and further experiments will aim toward an elucidation of the neural mechanisms involved in this form of learning.     

Memory retrieval time and memory capacity of the CA3 network: role of gamma frequency oscillations

The existence of recurrent synaptic connections in CA3 led to the hypothesis that CA3 is an autoassociative network similar to the Hopfield networks studied by theorists. CA3 undergoes gamma frequency periodic inhibition that prevents a persistent attractor state. This argues against the analogy to Hopfield nets, in which an attractor state can be used for working memory. However, we show that such periodic inhibition allows one cycle of recurrent excitatory activity and that this is sufficient for memory retrieval (within milliseconds). Thus, gamma oscillations are compatible with a long-term autoassociative memory function for CA3. A second goal of our work was to evaluate previous methods for estimating the memory capacity (P) of CA3. We confirm the equation, P = c/a(2), where c is the probability that any two cells are recurrently connected and a is the fraction of cells representing a memory item. In applying this to CA3, we focus on CA3a, the subregion where recurrent connections are most numerous (c = 0.2) and approximate randomness. We estimate that a memory item is represented by approximately 225 of the 70,000 neurons in CA3a (a = 0.003) and that approximately 20,000 memory items can be stored. Our general conclusion is that the physiological and anatomical findings of CA3a are consistent with an autoassociative function. The nature of the information that is associated in CA3a is discussed. We also discuss how the autoassociative properties of CA3 and the heteroassociative properties of dentate synapses (linking sequential memories) form an integrated system for the storage and recall of item sequences. The recall process generates the phase precession in dentate, CA3, and entorhinal cortex.     

The moderator role of intuitive versus deliberative decision making for the predictive validity of implicit and explicit measures

The Preference for Intuition and Deliberation (PID) scale aims at capturing stable general individual differences in terms of intuitive versus deliberative preferences in decision making. A study examined the psychometric properties of the English version of the PID, investigated whether the two subscales moderate the validity of implicit and explicit measures for incidental and deliberative evaluations and behaviours concerning fizzy soft drinks, and compared the predictive validity of two new implicit measures (ST‐IAT and ID‐EAST) and an explicit measure. Results showed an asymmetric weak double dissociation pattern only for behaviours. Additionally, a moderation effect suggested that the ST‐IAT better predicted sensory evaluation for people high in intuition and explicit attitudes better predicted benefit evaluation for people high in deliberation. Copyright © 2007 John Wiley & Sons, Ltd.     

Exploring temporal aspects of social identity: the concept of possible social identities

In the social identity model of reactions to negative social identity (Tajfel & Turner, 1979, 1986), the concept of cognitive alternatives focuses on individual and group perceptions of the possibility of changing group memberships or improving existing ones. In the current paper, the under-researched concept of cognitive alternatives is expanded so as to better encompass issues relating to the temporal dimension of social identity maintenance. Markus and Nurius' (1986) possible selves perspective is used as a starting point for exploring the manner in which social identity maintenance is influenced by cognitions about, and social representations of, a group's past and possible future. It is proposed that the concept of cognitive alternatives be expanded to incorporate possible social identities, which represent individual and shared cognitions about possible past group memberships, possible future group memberships, and perceptions of the possible past and future for current group memberships. The consequences of perceiving positive and negative possible social identities are examined, and methodological issues which might facilitate their empirical study addressed. © 1998 John Wiley & Sons, Ltd.     

Information seeking and reciprocity: a transformational analysis

The motivation to reciprocate is analyzed within the framework of interdependence theory, with focus on the process of transformation of situations. A model of transformation is presented for the motivation to reciprocate and hypotheses regarding allocation behavior and information seeking are derived. The hypotheses are tested in two experiments implementing a game where participants allocate payoff to self and other in a sequential way, with one participant able to gather costly information regarding the other's previous behavior. Individual differences in the motivation to reciprocate are assessed with the Personal Norm of Reciprocity questionnaire. Results show that participants with high motivation to reciprocate seek information regarding other's past behavior, and react to this information as the norm of reciprocity prescribes. Participants with low motivation to reciprocate prefer information regarding the future of the interaction (Study 1), or no information (Study 2), and behave in a more selfish way. Results are discussed with respect of (1) the transformation of situation process, (2) the role of reciprocity as an interpersonal motive, and (3) the validity of the individual differences measure. Copyright © 2003 John Wiley & Sons, Ltd.     

The distinction between desires and intentions

Within attitude theory the concepts of desires and intentions are not differentiated but are often treated as synonyms. However, we argue that there are theoretical reasons for distinguishing between desires and intentions, and we articulate three main criteria, perceived performability, action‐connectedness, and temporal framing, that differentiate between the two constructs. Two studies are reported to test the distinction. Study 1 (n = 188) revealed that desires, compared to intentions, are less performable, are less connected to actions, and are enacted over longer time frames. Study 2 (n = 249) showed, among other things, that the perceived feasibility for actions that are desired and intended is higher than for those that are only desired, but only when the action refers to relatively short time frames (i.e. 1 week or 4 weeks vs. 4 months). The findings are discussed in the light of the distinction between intentions and desires and the role that they play in individual decision making. Copyright © 2004 John Wiley & Sons, Ltd.