There have been several reports in the literature of faster visual lexical decisions to words that are semantically ambiguous. All current models of this ambiguity advantage assume that it is the presence of multiple unrelated meanings that produce this benefit. A set of three lexical decision experiments reported here challenge this assumption. We contrast the ambiguity seen in words like bark, which have multiple unrelated meanings, with words that have multiple related word senses (e.g., twist). In all three experiments we find that while multiple word senses do produce faster responses, ambiguity between multiple meanings delays recognition. These results suggest that, while competition between the multiple meanings of ambiguous words delays their recognition, the rich semantic representations associated with words with many senses facilitate their recognition. © 2002 Elsevier Science (USA) Key Words: lexical ambiguity; polysemy; distributed semantic representations.Many words are semantically ambiguous, and can refer to more than one concept. For example, bark can refer either to a part of a tree or to the sound made by a dog. To understand such words, we must select one of these different interpretations, normally on the basis of the context in which the word occurs.Words can be ambiguous in different ways; a word like bark has two semantically unrelated meanings, which seem to share the same written and spoken form purely by chance. More common than this type of accidental ambiguity is the systematic ambiguity between related word senses. For example, the word twist has a range of dictionary definitions including to make into a coil or spiral, to operate by turning, to alter the shape of, to misconstrue the meaning of, to wrench or sprain, and to squirm or writhe. The meaning of this word varies systematically according to the context in which the word is used; for example, there are important differences between what it means to twist an ankle compared with to twist the truth. However, although the meaning of the word is ambiguous between these different interpretations, the interpretations are closely related to each other both etymologically and semantically; this is quite unlike the ambiguity for a word like bark.
A number of regions of the temporal and frontal lobes are known to be important for spoken language comprehension, yet we do not have a clear understanding of their functional role(s). In particular, there is considerable disagreement about which brain regions are involved in the semantic aspects of comprehension. Two functional magnetic resonance studies use the phenomenon of semantic ambiguity to identify regions within the fronto-temporal language network that subserve the semantic aspects of spoken language comprehension. Volunteers heard sentences containing ambiguous words (e.g. 'the shell was fired towards the tank') and well-matched low-ambiguity sentences (e.g. 'her secrets were written in her diary'). Although these sentences have similar acoustic, phonological, syntactic and prosodic properties (and were rated as being equally natural), the high-ambiguity sentences require additional processing by those brain regions involved in activating and selecting contextually appropriate word meanings. The ambiguity in these sentences goes largely unnoticed, and yet high-ambiguity sentences produced increased signal in left posterior inferior temporal cortex and inferior frontal gyri bilaterally. Given the ubiquity of semantic ambiguity, we conclude that these brain regions form an important part of the network that is involved in computing the meaning of spoken sentences.
Many word forms map onto multiple meanings (e.g., ‘‘ace”). The current experiments explore the extent to which adults reshape the lexical–semantic representations of such words on the basis of experience, to increase the availability of more recently accessed meanings. A naturalistic web-based experiment in which primes were presented within a radio programme (Experiment 1; N = 1800) and a lab-based experiment (Experiment 2) show that when listeners have encountered one or two disambiguated instances of an ambiguous word, they then retrieve this primed meaning more often (compared with an unprimed control condition). This word-meaning priming lasts up to 40 min after exposure, but decays very rapidly during this interval. Experiments 3 and 4 explore longer term word-meaning priming by measuring the impact of more extended, naturalistic encounters with ambiguous words: recreational rowers (N = 213) retrieved rowing related meanings for words (e.g., ‘‘feather”) more often if they had rowed that day, despite a median delay of 8 hours. The rate of rowing-related interpretations also increased with additional years’ rowing experience. Taken together these experiments show that individuals’ overall meaning preferences reflect experience across a wide range of timescales from minutes to years. In addition, priming was not reduced by a change in speaker identity (Experiment 1), suggesting that the phenomenon occurs at a relatively abstract lexical–semantic level. The impact of experience was reduced for older adults (Experiments 1, 3, 4) suggesting that the lexical–semantic representations of younger listeners may be more malleable to current linguistic experience
Abstract& How objects are represented and processed in the brain is a central topic in cognitive neuroscience. Previous studies have shown that knowledge of objects is represented in a featurebased distributed neural system primarily involving occipital and temporal cortical regions. Research with nonhuman primates suggest that these features are structured in a hierarchical system with posterior neurons in the inferior temporal cortex representing simple features and anterior neurons in the perirhinal cortex representing complex
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