Language Evolution and Computation Bibliography

The mental model theory claims that the ability to falsify is at the core of human rationality. We assume that cognitive conflicts (CCs) and socio-cognitive conflicts (SCCs) induce falsification, and thus improve syllogistic reasoning performance. Our first study assesses adults' ability to reason in two different conditions in a single experimental session. In both conditions the participants are presented with conclusions alternative to their own. In the CC condition they are told that these conclusions are casual, in the SCC condition they are told they have been produced by another individual. The second study is analogous to the first, with the exception that the participants deal with the two conditions in two different experimental sessions. The overall results reveal that falsification is enhanced by conflicts experienced at the cognitive level. The results also reveal that learning to reason occurs in adults, when tested in two distinct experimental periods.

In this paper, we claim that the problem of conditionals should be dealt with by carefully distinguishing between thinking conditional propositions and conditional thinking, i.e. thinking on the basis of some supposition. This distinction deserves further investigation, if we are to make sense of some old and new experimental data concerning the understanding and the assertion of conditional sentences. Here we will argue that some of these data seem to refute the mental models theory of conditional reasoning, setting the ground for a different approach to the cognitive study of conditionals.

This symposium includes a selection of articles on the origins and evolution of language. These are extended version of selected papers presented at ``EVOLANG6: The Sixth International Conference on the Evolution of Language'' that was held in Rome in April 2006. This selection of papers provides a multi-methodological view of different approaches to, and theoretical explanations of, the evolution of language.

We focus on the evolution of action capabilities which set the stage for language, rather than analyzing how further brain evolution built on these capabilities to yield a language-ready brain. Our framework is given by the Mirror System Hypothesis, which charts a progression from a monkey-like mirror neuron system (MNS) to a chimpanzee-like mirror system that supports simple imitation and thence to a human-like mirror system that supports complex imitation and language. We present the MNS2 model, a new model of action recognition learning by mirror neurons of the macaque brain and augmented competitive queuing, a model of opportunistic scheduling of action sequences as background for analysis of modeling strategies for ``simple imitation'' as seen in the great apes and ``complex/goal-directed imitation'' as seen in humans. Implications for the study of language are briefly noted.

I discuss the ubiquity of power law distributions in language organisation (and elsewhere), and argue against Miller's (The mating mind: How sexual choice shaped the evolution of human nature, William Heinemann, London, 2000) argument that large vocabulary size is a consequence of sexual selection. Instead I argue that power law distributions are evidence that languages are best modelled as dynamical systems but raise some issues for models of iterated language learning.

The term embodiment identifies a theory that meaning and semantics cannot be captured by abstract, logical systems, but are dependent on an agent's experience derived from being situated in an environment. This theory has recently received a great deal of support in the cognitive science literature and is having significant impact in artificial intelligence. Memetics refers to the theory that knowledge and ideas can evolve more or less independently of their human-agent substrates. While humans provide the medium for this evolution, memetics holds that ideas can be developed without human comprehension or deliberate interference. Both theories have profound implications for the study of language -- its potential use by machines, its acquisition by children and of particular relevance to this special issue, its evolution. This article links the theory of memetics to the established literature on semantic space, then examines the extent to which these memetic mechanisms might account for language independently of embodiment. It then seeks to explain the evolution of language through uniquely human cognitive capacities which facilitate memetic evolution.

Chicken-Hawk is a social-dilemma game that distinguishes uncoordinated from coordinated cooperation. In tests with players belonging to a culturally homogeneous population, natural-language ``cheap talk'' led to efficient coordination, while nonlinguistic signaling yielded uncoordinated altruism. In a subsequent test with players from a moderately more heterogeneous population nearby, the ``cheap talk'' condition still produced better coordination than other signaling conditions, but at a lower level and with fewer acts of altruism overall. Implications are: (1) without language, even willing cooperators coordinate poorly; (2) given a sufficiently homogeneous social group, language can coordinate cooperation in the face of opportunities for anonymous defection; (3) coordination therefore depends not on merely a general propensity to cooperate but on the overlap of social identities, which are always costly to acquire and maintain. So far as linguistic variation establishes how much social identities overlap, natural-language ``cheap talk'' is self-insuring, suggesting that linguistic variation is itself adaptive.

Many scholars assume a connection between the evolution of language and that of distinctively human group-level morality. Unfortunately, such thinkers frequently downplay a central implication of modern Darwinian theory, which precludes the possibility of innate psychological mechanisms evolving to benefit the group at the expense of the individual. Group level moral regulation is indeed central to public life in all known human communities. The production of speech acts would be impossible without this. The challenge, therefore, is to explain on a Darwinian basis how life could have become subject to the rule of law. Only then will we have an appropriate social framework in which to contextualize our models of how language may have evolved.

Primate vocal communication is very different from human language. Differences are most pronounced in call production. Differences in production have been overemphasized, however, and distracted attention from the information that primates acquire when they hear vocalizations. In perception and cognition, continuities with language are more apparent. We suggest that natural selection has favored nonhuman primates who, upon hearing vocalizations, form mental representations of other individuals, their relationships, and their motives. This social knowledge constitutes a discrete, combinatorial system that shares several features with language. It is probably a general primate characteristic whose appearance pre-dates the evolution of spoken language in our hominid ancestors. The prior evolution of social cognition created individuals who were preadapted to develop language. Several features thought to be unique to language --like discrete combinatorics and the encoding of propositional information-- were not introduced by language. They arose, instead, because understanding social life and predicting others' behavior requires a particular style of thinking.