SAN FRANCISCO, July 16 -- Researchers at two U.S. universities have mapped 1,100 years of metaphoric English language and detected patterns in how English speakers have added figurative word meanings to their vocabulary.
Published in the August issue of the journal Cognitive Psychology, the study demonstrates how humans throughout history have used language that originally described palpable experiences such as "grasping an object" to describe more intangible concepts such as "grasping an idea."
While providing the first large-scale evidence that the creation of new metaphorical word meanings is systematic, the findings in the paper titled "Evolution of word meanings through metaphorical mapping: Systematicity over the past millennium" are expected to inform efforts to design natural language processing systems by helping them understand creativity in human language.
About natural language processing systems such as Siri, an intelligent personal assistant for use with iPhone, Apple Watch and other electronics from Apple Inc., study lead author Yang Xu, a postdoctoral researcher in linguistics and cognitive science at the University of California, Berkeley, noted that "although such systems are capable of understanding many words, they are often tripped up by creative uses of words that go beyond their existing, pre-programmed vocabularies."
Xu and senior author Mahesh Srinivasan, an assistant professor of psychology at UC Berkeley, conducted the study with Barbara Malt, a psychology professor at Lehigh University in Pennsylvania.
Using the Metaphor Map of English database, the researchers examined more than 5,000 examples from the past millennium in which word meanings from one semantic domain, such as "water," were extended to another semantic domain, such as "mind." The authors called the original semantic domain the "source domain" and the domain that the metaphorical meaning was extended to the "target domain."
More than 1,400 online participants were recruited to rate semantic domains such as "water" or "mind" according to the degree to which they were related to the external world (light, plants), animate things (humans, animals), or intense emotions (excitement, fear). These ratings were fed into computational models that the researchers had developed to predict which semantic domains had been the sources or targets of metaphorical extension.
In comparing their computational predictions against the actual historical record provided by the Metaphor Map of English, the researchers found that their models correctly forecast about 75 percent of recorded metaphorical language mappings over the past millennium, and that the degree to which a domain is tied to experience in the external world, such as "grasping a rope," was the primary predictor of how a word would take on a new metaphorical meaning such as "grasping an idea."
For example, they found that words associated with textiles, digestive organs, wetness, solidity and plants were more likely to provide sources for metaphorical extension, while mental and emotional states, such as excitement, pride and fear were more likely to be the targets of metaphorical extension.
"The use of concrete language to talk about abstract ideas may unlock mysteries about how we are able to communicate and conceptualize things we can never see or touch," noted Srinivasan. "Our results may also pave the way for future advances in artificial intelligence."
