196,916 research outputs found
How training and testing histories affect generalization: a test of simple neural networks
No full textWe show that a simple network model of associative learning can\ud
reproduce three findings that arise from particular training and\ud
testing procedures in generalization experiments: the effect of 1)\ud
``errorless learning'' and 2) extinction testing on peak shift, and\ud
3) the central tendency effect. These findings provide a true test\ud
of the network model, which was developed to account for other\ud
penhomena, and highlight the potential of neural networks to study\ud
phenomena that depend on sequences of experiences with many stimuli.\ud
Our results suggest that at least some such phenomena, e.g.,\ud
stimulus range effects, may derive from basic mechanisms of\ud
associative memory rather than from more complex memory processes
Geometric factors influencing the diet of vertebrate predators in marine and terrestrial environments
No full textPredator–prey relationships are vital to ecosystem function and there is a need for greater predictive
understanding of these interactions. We develop a geometric foraging model predicting minimum
prey size scaling in marine and terrestrial vertebrate predators taking into account habitat
dimensionality and biological traits. Our model predicts positive predator–prey size relationships
on land but negative relationships in the sea. To test the model, we compiled data on diets of 794
predators (mammals, snakes, sharks and rays). Consistent with predictions, both terrestrial endotherm
and ectotherm predators have significantly positive predator–prey size relationships. Marine
predators, however, exhibit greater variation. Some of the largest predators specialise on small
invertebrates while others are large vertebrate specialists. Prey–predator mass ratios were generally
higher for ectothermic than endothermic predators, although dietary patterns were similar.
Model-based simulations of predator–prey relationships were consistent with observed relationships,
suggestin
Evolution of imitation does not explain the origin of human cumulative culture
No full textBecause culture requires transmission of information between individuals, thinking about the origin of culture has mainly focused on the genetic evolution of abilities for social learning. Current theory considers how social learning affects the adaptiveness of a single cultural trait, yet human culture is consists of the accumultion of very many traits. Here we introduce a new modeling strategy that tracks the adaptive value of many cultural traits, showing that genetic evolution favors only limited social learning owing to the
accumulation of maladaptive as well as adaptive culture. We further show that culture can be adaptive, and refined social learning can evolve, if individuals can identify and discard maladaptive culture. This suggests that the evolution of such ``adaptive filtering'' mechanisms may have been crucial for the birth of human culture
Neural networks and animal behavior
No full textDAL SITO DELL'EDITORE:
How can we make better sense of animal behavior by using what we know about the brain? This is the first book that attempts to answer this important question by applying neural network theory. Scientists create Artificial Neural Networks (ANNs) to make models of the brain. These networks mimic the architecture of a nervous system by connecting elementary neuron-like units into networks in which they stimulate or inhibit each other's activity in much the same way neurons do. This book shows how scientists can employ ANNs to analyze animal behavior, explore the general principles of the nervous systems, and test potential generalizations among species. The authors focus on simple neural networks to show how ANNs can be investigated by math and by computers. They demonstrate intuitive concepts that make the operation of neural networks more accessible to nonspecialists.
The first chapter introduces various approaches to animal behavior and provides an informal introduction to neural networks, their history, and their potential advantages. The second chapter reviews artificial neural networks, including biological foundations, techniques, and applications. The following three chapters apply neural networks to such topics as learning and development, classical instrumental condition, and the role of genes in building brain networks. The book concludes by comparing neural networks to other approaches. It will appeal to students of animal behavior in many disciplines. It will also interest neurobiologists, cognitive scientists, and those from other fields who wish to learn more about animal behavior
METTERSI IN CAMMINO. TRE ROMANZI STORICI DI PER OLOV ENQUIST
No full textAnalisi di tre romanzi storici di Per Olov Enquist, tra i maggiori autori svedesi del Novecento. L'articolo è stato ripubblicato come postfazione del romanzo "Il viaggio di Lewi" di Enquist (Iperborea, 2004). Si veda quella descrizione
Cumulative culture and explosive demographic transitions
No full textA demographic transition is a change in the pattern of growth of
a population. Human history records several kinds of such
transitions, e.g., from stability to growth or between different
kinds of growth. Culture is often implied as the main fuel of
demographic transitions, but theorizing is so far limited to
verbal arguments. Here we study two simple formal models in
which population size and the amount of culture in a population
influence each other's dynamics. The first model has two
regimes: an equilibrium regime in which both population size and
amount of culture reach stable values, and an explosive regime
in which both variables increase exponentially without bound. A
transition between these regimes is caused by changes in
parameters that describe the accuracy of cultural transmission
and the interaction between demography and culture. The second
model suggests that a transition from extensive to intensive
accumulation of culture may derive from a qualitative change in
how individuals cooperate to create culture
Culture creates its own rules: the rise of conservatism and persuasion
No full textMany aspects of human behaviour are attributed to culture, but the
extent to which culture is influenced by our genes remains strongly
debated. Cultural evolution has been viewed as
controlled by a genetically determined human
nature, as a distinct process in
interaction with genetic evolution, and as an
autonomous process wholly free from genetic
influences. Proponents of the latter view often
imply that cultural evolution may take any direction, but this is
not necessarily true. Here we show how forces that operate within
culture itself can systematically shape behaviour and personality
traits that have a significant impact on cultural change.
Specifically, we show that both unwillingness to change
(``conservatism'') and influencing others to become like yourself
(``persuasion'') are traits favoured by cultural evolution, even
when individuals have no genetic predisposition towards these
traits
Critical social learning: A solution to Rogers' paradox of non-adaptive culture
No full textWe expand Rogers’ (1988) game theoretical model of the evolution of
social learning considering that 1) individual learning does not always pro-
duce optimal behavior; 2) social learning is not always accurate. Further, we
introduce a “critical social learning” strategy that tries to solve an adaptive
problem first by social learning, and then by individual learning if socially
acquired behavior proves unsatisfactory. This strategy is always superior
to pure social learning and has typically higher fitness than pure individual
learning, providing a solution to Rogers’ paradox of non-adaptive culture.
Critical social learning is an evolutionarily stable strategy (ESS) unless cul-
tural transmission is highly unfaithful, the environment highly variable or
social learning much costlier than individual learning, and quite independent
of the success rate of individual learning. We compare the model to empir-
ical data on social learning and on spatial variation in primate cultures, and
list three requirements for adaptive culture
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