Most words in English are ambiguous between different interpretations; words can mean different things in different contexts. We investigate the implications of different types of semantic ambiguity for connectionist models of word recognition. We present a model in which there is competition to activate distributed semantic representations. The model performs well on the task of retrieving the different meanings of ambiguous words, and is able to simulate data reported by Rodd, Gaskell, and Marslen‐Wilson [J. Mem. Lang. 46 (2002) 245] (...) on how semantic ambiguity affects lexical decision performance. In particular, the network shows a disadvantage forwords with multiple unrelated meanings (e.g., bark) that coexists with a benefit for words with multiple related word senses (e.g., twist). The ambiguity disadvantage arises because of interference between the different meanings, while the sense benefit arises because of differences in the structure of the attractor basins formed during learning. Words with few senses develop deep, narrow attractor basins, while words with many senses develop shallow, broad basins. We conclude that the mental representations of word meanings can be modelled as stable states within a high‐dimensional semantic space, and that variations in the meanings of words shape the landscape of this space. (shrink)

A critical property of the perception of spoken words is the transient ambiguity of the speech signal. In localist models of speech perception this ambiguity is captured by allowing the parallel activation of multiple lexical representations. This paper examines how a distributed model of speech perception can accommodate this property. Statistical analyses of vector spaces show that coactivation of multiple distributed representations is inherently noisy, and depends on parameters such as sparseness and dimensionality. Furthermore, the characteristics of coactivation vary considerably, (...) depending on the organization of distributed representations within the mental lexicon. This view of lexical access is supported by analyses of phonological and semantic word representations, which provide an explanation of a recent set of experiments on coactivation in speech perception (Gaskell & Marslen–Wilson, 1999). (shrink)

A number of recent studies have examined the effects of phonological variation on the perception of speech. These studies show that both the lexical representations of words and the mechanisms of lexical access are organized so that natural, systematic variation is tolerated by the perceptual system, while a general intolerance of random deviation is maintained. Lexical abstraction distinguishes between phonetic features that form the invariant core of a word and those that are susceptible to variation. Phonological inference relies on the (...) context of surface changes to retrieve the underlying phonological form. In this article we present a model of these processes in speech perception, based on connectionist learning techniques. A simple recurrent network was trained on the mapping from the variant surface form of speech to the underlying form. Once trained, the network exhibited features of both abstraction and inference in its processing of normal speech, and predicted that similar behavior will be found in the perception of nonsense words. This prediction was confirmed in subsequent research (Gaskell & Marslen-Wilson, 1994). (shrink)

Biotechnology is one of the fastest-growing areas of scientific, technical and industrial innovation and one of the most controversial. As developments have occurred such as genetic test therapies and the breeding of genetically modified food crops, so the public debates have become more heated and grave concerns have been expressed about access to genetic information, labelling of genetically modified foods and human and animal cloning. Across Europe, public opinion has become a crucial factor in the ability of governments and biotech (...) industries to exploit the new technology. This 2002 book presents the results of a unique cross-national and cross-disciplinary study of the relationship between the development of new biotechnology and public perception, media coverage and policy formulation. It outlines a conceptual framework for understanding these issues and contains a number of empirical studies including studies of the international controversies surrounding the cloning of Dolly the sheep and GM Soya. (shrink)

MATERIALISTS claim that in principle mentality could be accounted for entirely by properties of matter. They must, of course, clarify, as far as possible, the precise scope of the concept "properties of matter." According to materialists there exists only one type of "substance" in the universe, namely matter. Sophisticated experimental and theoretical analyses have led contemporary physicists to interpret known material entities as being composed of two classes of elementary particles, namely quarks and leptons and constituents of interaction fields that (...) mediate interactions between some or all of the elementary particles and which comprise photons, gluons, intermediate bosons and gravitons. For instance, protons and neutrons are composed--by hypothesis--of quarks, while electrons are probably the most familiar leptons. Whether any analyzed and postulated elementary particles and constituents of interaction fields are "ultimate" components of matter can never be known. It remains always possible that more basic subcomponents of known components will be discovered. This has happened repeatedly throughout the history of physics. Hence, what physicists understand by the "physical properties" of the basic components of matter must always remain expressed in terms of usually intricate hypothetico-deductive theories which are tentative and fallible. Contemporary relativistic quantum mechanics of elementary particles and of interaction fields provide typical examples of such hypothetico-deductive theories relating to present known basic components of matter. (shrink)

SummaryExtremism in the environment‐versus innateness controversy in the behavioural sciences and in human sociobiology is being examined. Genetic effects can be severely modified or overruled by environmental factors, but may, nevertheless, be important. Dawkins' view that we are survival machines programmed to subserve selfish genes seems untenable and is a root of racialism. It is also argued that morality is compatible with mixed genetic and environmental control of brains via existing biological machinery.

We comment on the previous paper by L. Basano. In particular, we show that its Section 2 is kinematically incorrect (the dynamics of a two-body interaction through tachyon exchange, incidentally, has already been thoroughly expounded in one paper of ours). Its Section 1 is simply a rather subjective introduction. As to its Section 3, containing indeed interesting problems, we again briefly refer to our earlier work. Our conclusions are still in favor of “au revoir to tachyons!,” even if it is (...) known that inside our cosmos tachyons are more likely to have a role in physics (e.g., in elementary particle and black-hole physics) as “exchanged objects” rather than as “asymptotically free” objects. (shrink)

The Four-Colour Theorem (4CT) proof, presented to the mathematical community in a pair of papers by Appel and Haken in the late 1970's, provoked a series of philosophical debates. Many conceptual points of these disputes still require some elucidation. After a brief presentation of the main ideas of Appel and Haken’s procedure for the proof and a reconstruction of Thomas Tymoczko’s argument for the novelty of 4CT’s proof, we shall formulate some questions regarding the connections between the points raised by (...) Tymoczko and some Wittgensteinian topics in the philosophy of mathematics such as the importance of the surveyability as a criterion for distinguishing mathematical proofs from empirical experiments. Our aim is to show that the “characteristic Wittgensteinian invention” (Mühlhölzer 2006) – the strong distinction between proofs and experiments – can shed some light in the conceptual confusions surrounding the Four-Colour Theorem. (shrink)

The general concept of a causal system has been basic in scientific thought. It may be formulated as follows. The system in question possesses certain measurable attributes such as those of dimensions, temperature, and so forth. In the case of a causal system, it is affirmed that the subsequent development of the system from a known initial condition—that is, a condition in which the measurable variables have known values—is uniquely determined by these values. More definitely, the value of these same (...) variables after any interval of time depends only on the initial values of the variables and the time interval which has elapsed. (shrink)

At Phaedo 59b Echecrates asks Phaedo who was present on the day when Socrates drank the hemlock in prison. Various Athenians are named , then various foreigners , but when Echecrates subsequently asks if two other foreigners, Aristippus and Cleombrotus, were present, Phaedo replies that they were said to be in Aegina . After this fleeting reference to Cleombrotus, Plato does not mention him again in the Phaedo or any other dialogue; and yet in later antiquity a certain Cleombrotus of (...) Ambracia rose to fame in connection with the Phaedo. Callimachus is our earliest source for the anecdote which immortalized the Ambracian : Επας ‘Ἥλιε αρε’ Κλεμβρτος μβρακιτης λατ' φ' Ψηλο τεεος ες δην, ζιον οδν δν θαντου κακν, λλ Πλτωνος ν τ περ Ψυς γρμμ' ναλεζμενος. (shrink)