Synergy Makes Direct Perception Inefficient.

A typical claim in anti-representationalist approaches to cognition such as ecological psychology or radical embodied cognitive science is that ecological information is sufficient for guiding behavior. According to this view, affordances are immediately perceptually available to the agent (in the so-called "ambient energy array"), so sensory data does not require much further inner processing. As a consequence, mental representations are explanatorily idle: perception is immediate and direct. Here we offer one way to formalize this direct-perception claim and identify some important limits to it. We argue that the claim should be read as saying that successful behavior just implies picking out affordance-related information from the ambient energy array. By relying on the Partial Information Decomposition framework, and more concretely on its development of the notion of synergy, we show that in multimodal perception, where various energy arrays carry affordance-related information, the "just pick out affordance-related information" approach is very inefficient, as it is bound to miss all synergistic components. Efficient multimodal information combination requires transmitting sensory-specific (and not affordance-specific) information to wherever it is that the various information streams are combined. The upshot is that some amount of computation is necessary for efficient affordance reconstruction.

The Information-Processing Perspective on Categorization.

Categorization behavior can be fruitfully analyzed in terms of the trade-off between as high as possible faithfulness in the transmission of information about samples of the classes to be categorized, and as low as possible transmission costs for that same information. The kinds of categorization behaviors we associate with conceptual atoms, prototypes, and exemplars emerge naturally as a result of this trade-off, in the presence of certain natural constraints on the probabilistic distribution of samples, and the ways in which we measure faithfulness. Beyond the general structure of categorization in these circumstances, the same information-centered perspective can shed light on other, more concrete properties of human categorization performance, such as the results of certain prominent experiments on supervised categorization.

Nuclear-medicine probes: Where we are and where we are going.

Nuclear medicine probes turned into the key for the identification and precise location of sentinel lymph nodes and other occult lesions (i.e., tumors) by using the systemic administration of radiotracers. Intraoperative nuclear probes are key in the surgical management of some malignancies as well as in the determination of positive surgical margins, thus reducing the extent and potential surgery morbidity. Depending on their application, nuclear probes are classified into two main categories, namely, counting and imaging. Although counting probes present a simple design, are handheld (to be moved rapidly), and provide only acoustic signals when detecting radiation, imaging probes, also known as cameras, are more hardware-complex and also able to provide images but at the cost of an increased intervention time as displacing the camera has to be done slowly. This review article begins with an introductory section to highlight the relevance of nuclear-based probes and their components as well as the main differences between ionization- (semiconductor) and scintillation-based probes. Then, the most significant performance parameters of the probe are reviewed (i.e., sensitivity, contrast, count rate capabilities, shielding, energy, and spatial resolution), as well as the different types of probes based on the target radiation nature, namely: gamma (γ), beta (ß) (positron and electron), and Cherenkov. Various available intraoperative nuclear probes are finally compared in terms of performance to discuss the state-of-the-art of nuclear medicine probes. The manuscript concludes by discussing the ideal probe design and the aspects to be considered when selecting nuclear-medicine probes.

The meaning of biological signals.

We introduce the virtual special issue on content in signalling systems. The issue explores the uses and limits of ideas from evolutionary game theory and information theory for explaining the content of biological signals. We explain the basic idea of the Lewis-Skyrms sender-receiver framework, and we highlight three key themes of the issue: (i) the challenge of accounting for deception, misinformation and false content, (ii) the relevance of partial or total common interest to the evolution of meaningful signals, and (iii) how the sender-receiver framework relates to teleosemantics.

Deception as cooperation.

I develop a rate-distortion analysis of signaling games with imperfect common interest. Sender and receiver should be seen as jointly managing a communication channel with the objective of minimizing two independent distortion measures. I use this analysis to identify a problem with 'functional' theories of deception, and in particular Brian Skyrms's: there are perfectly cooperative, non-exploitative instances of channel management that come out as manipulative and deceptive according to those theories.

The Organizational Account of Function is an Etiological Account of Function.

The debate on the notion of function has been historically dominated by dispositional and etiological accounts, but recently a third contender has gained prominence: the organizational account. This original theory of function is intended to offer an alternative account based on the notion of self-maintaining system. However, there is a set of cases where organizational accounts seem to generate counterintuitive results. These cases involve cross-generational traits, that is, traits that do not contribute in any relevant way to the self-maintenance of the organism carrying them, but instead have very important effects on organisms that belong to the next generation. We argue that any plausible solution to the problem of cross-generational traits shows that the organizational account just is a version of the etiological theory and, furthermore, that it does not provide any substantive advantage over standard etiological theories of function.

Communication and common interest.

Explaining the maintenance of communicative behavior in the face of incentives to deceive, conceal information, or exaggerate is an important problem in behavioral biology. When the interests of agents diverge, some form of signal cost is often seen as essential to maintaining honesty. Here, novel computational methods are used to investigate the role of common interest between the sender and receiver of messages in maintaining cost-free informative signaling in a signaling game. Two measures of common interest are defined. These quantify the divergence between sender and receiver in their preference orderings over acts the receiver might perform in each state of the world. Sampling from a large space of signaling games finds that informative signaling is possible at equilibrium with zero common interest in both senses. Games of this kind are rare, however, and the proportion of games that include at least one equilibrium in which informative signals are used increases monotonically with common interest. Common interest as a predictor of informative signaling also interacts with the extent to which agents' preferences vary with the state of the world. Our findings provide a quantitative description of the relation between common interest and informative signaling, employing exact measures of common interest, information use, and contingency of payoff under environmental variation that may be applied to a wide range of models and empirical systems.

A brief assessment of eating habits and weight gain in a Mediterranean cohort.

Assessment of eating habits (EH) through closed questions could be an alternative tool to assess diet as a predictor of weight change in epidemiological studies. The aim was to assess the association between baseline EH and the risk of weight gain or becoming overweight/obese in a Spanish dynamic prospective cohort (the Seguimiento Universidad de Navarra Project) of 10 509 participants. The baseline questionnaire included ten short questions with two possible answers: yes or no. We calculated a baseline EH score, categorised in quartiles, positively weighting answers on more fruit, vegetables, fish and fibre and less meat, sweets and pastries, fat, butter, fatty meats and added sugar in drinks. Reducing the consumption of meat or fat and removing fat from meat were significantly associated with lower weight gain. The partial correlation coefficient between EH score and weight change was - 0·033 (P = 0·001). We observed 1063 cases of incident overweight/obesity among 7217 participants without overweight/obesity at baseline. Trying to eat more fruit, fish or fibre and less meat was inversely significantly associated with incident overweight/obesity. Those participants in the upper quartile of the score were at a 38 % (adjusted OR 0·62; 95 % CI 0·48, 0·81) lower risk of developing overweight/obesity during the follow-up compared with those in the lower quartile. However, the receiver-operating characteristic curves for the model with and without the EH score were materially identical. Despite the apparent significant inverse association, this score had a low predictive value for future weight gain and for incident overweight/obesity in a Mediterranean population, although some EH were independently and positively associated with weight gain.