Army ants dynamically adjust living bridges in response to a cost–benefit trade-off

The ability of individual animals to create functional structures by joining together is rare and confined to the social insects. Army ants (Eciton) form collective assemblages out of their own bodies to perform a variety of functions that benefit the entire colony. Here we examine ‟bridges” of linked individuals that are constructed to span gaps in the colony’s foraging trail. How these living structures adjust themselves to varied and changing conditions remains poorly understood. Our field experiments show that the ants continuously modify their bridges, such that these structures lengthen, widen, and change position in response to traffic levels and environmental geometry. Ants initiate bridges where their path deviates from their incoming direction and move the bridges over time to create shortcuts over large gaps. The final position of the structure depended on the intensity of the traffic and the extent of path deviation and was influenced by a cost-benefit trade-off at the colony level, where the benefit of increased foraging trail efficiency was balanced by the cost of removing workers from the foraging pool to form the structure. To examine this trade-off, we quantified the geometric relationship between costs and benefits revealed by our experiments. We then constructed a model to determine the bridge location that maximized foraging rate, which qualitatively matched the observed movement of bridges. Our results highlight how animal self-assemblages can be dynamically modified in response to a group-level cost-benefit trade-off, without any individual unit’s having information on global benefits or costs.

Closed-loop brain training: The science of neurofeedback

Neurofeedback is a psychophysiological procedure in which online feedback of neural activation is provided to the participant for the purpose of self-regulation. Learning control over specific neural substrates has been shown to change specific behaviours. As a progenitor of brain–machine interfaces, neurofeedback has provided a novel way to investigate brain function and neuroplasticity. In this Review, we examine the mechanisms underlying neurofeedback, which have started to be uncovered. We also discuss how neurofeedback is being used in novel experimental and clinical paradigms from a multidisciplinary perspective, encompassing neuroscientific, neuroengineering and learning-science viewpoints.

Problem Forming, Problem Finding, and Problem Solving in Design

This meeting [1], representing a convergence of students of design from a range of wholly dissimilar disciplines, is an event of major significance. It is significant that the meeting is being held at all that all of you recognize your common concerns. It is significant that we are gaining deep insights into the design process itself. If it is pretentious to talk about the “science of design,” at least we know now that there are truths about design that can be formulated and communicated, general truths that seem to apply to design as each of us knows it, in his or her particular professional domain.

But perhaps it is not really pretentious to speak of the science of design. There are principles that are widely applicable, and increasingly, we are finding ways of implementing these principles on electronic computers, and thereby securing the powerful assistance of those computers in the process of design. Let’s compromise on “the art and science of design.”

In recent years, the awareness of our communalities, whatever the specific field in which we work, has been hastened by the applications of computers to design: expert systems, computer aided design, artificial intelligence. Because their programs are open to inspection, computers allow us to look at the design process. The program is a tangible, concrete object. And in order to construct programs to design or assist design, we have to try to understand the process. That process is basically the same, whether it is carried out by people or computers, or, as is increasingly the case, by both in collaboration.

The psychology and neuroscience of forgetting

Traditional theories of forgetting are wedded to the notion that cue-overload interference procedures (often involving the A-B, A-C list-learning paradigm) capture the most important elements of forgetting in everyday life. However, findings from a century of work in psychology, psychopharmacology, and neuroscience converge on the notion that such procedures may pertain mainly to forgetting in the laboratory and that everyday forgetting is attributable to an altogether different form of interference. According to this idea, recently formed memories that have not yet had a chance to consolidate are vulnerable to the interfering force of mental activity and memory formation (even if the interfering activity is not similar to the previously learned material). This account helps to explain why sleep, alcohol, and benzodiazepines all improve memory for a recently learned list, and it is consistent with recent work on the variables that affect the induction and maintenance of long-term potentiation in the hippocampus.

Intuition: A Social Cognitive Neuroscience Approach

This review proposes that implicit learning processes are the cognitive substrate of social intuition. This hypothesis is supported by (a) the conceptual correspondence between implicit learning and social intuition (nonverbal communication) and (b) a review of relevant neuropsychological (Huntington’s and Parkinson’s disease), neuroimaging, neurophysiological, and neuroanatomical data. It is concluded that the caudate and putamen, in the basal ganglia, are central components of both intuition and implicit learning, supporting the proposed relationship. Parallel, but distinct, processes of judgment and action are demonstrated at each of the social, cognitive, and neural levels of analysis. Additionally, explicit attempts to learn a sequence can interfere with implicit learning. The possible relevance of the computations of the basal ganglia to emotional appraisal, automatic evaluation, script processing, and decision making are discussed.