Dead parrots make bad pets: Exploring modifier effects in noun phrases

Proceedings of the Third Joint Conference on Lexical and Computational Semantics (*SEM 2014), pages 171–181, Dublin, Ireland, August 23-24 2014. Dead parrots make bad pets: Exploring modifier effects in noun phrases Germ´an Kruszewski and Marco Baroni Center for Mind/Brain Sciences (University of Trento, Italy) (german.kruszewski|marco.baroni)@unitn.it Abstract Sometimes modifiers have a strong effect on core aspects of the meaning of the nouns they are attached to: A parrot is a desirable pet, but a dead parrot is, at the very least, a rather unusual household companion. In order to stimulate compu- tational research into the impact of mod- ification on phrase meaning, we collected and made available a large dataset contain- ing subject ratings for a variety of noun phrases and the categories they might be- long to. We propose to use compositional distributional semantics to model these data, experimenting with numerous distri- butional semantic spaces, phrase compo- sition methods and asymmetric similarity measures. Our models capture a statis- tically significant portion of the data, al- though much work is still needed before we achieve a full computational account of modification effects. 1 Introduction Not all modifiers are created equal. Green parrots have all essential qualities of parrots, but dead par- rots don’t. For example, as vocally argued by the disgruntled costumer in Monty Python’s famous Dead Parrot Sketch,1 dead parrots make rather poor pet birds. In modifier-head constructions (that, for the purpose of this article, we restrict to right-headed adjective-noun and noun-noun con- structions), modifiers are not simply picking a sub- set of the denotation of the head they modify, but they are often distorting the properties of the head in a radical manner. These modifier effects on phrase meaning have been studied extensively by theoretical linguists, 1http://en.wikipedia.org/wiki/Dead_ Parrot_sketch who have focused primarily on the extreme case of intensional modifiers such as fake, alleged and toy, where the phrase denotes something that is no longer (or is not necessarily) a head (a toy gun is not a gun). See McNally (2013) for a re- cent review of the linguistic literature. Cognitive scientists have looked at modification phenomena within the general study of conceptual combina- tion (see Chapter 12 of Murphy (2002) for an ex- tensive review). The cognitive tradition has fo- cused on how modification affects prototypicality: a guppy is the prototypical pet fish, but it is neither a typical pet nor a typical fish (Smith and Osher- son, 1984). This line of research has highlighted how strong modification effects might be the rule, rather than the exception: Wisniewski (1997) re- ports that, when subjects were asked to provide the meaning for more than 200 novel modifier- head constructions, “70% [of the answers] in- volved the construal of a noun’s referent as some- thing other than the typical category named by the noun [head].” Indeed, recent research suggests that even the most stereotypical modifiers affect prototypicality, so that subjects are less willing to attribute to quacking ducks such obvious duck properties as having webbed feet (Connolly et al., 2007). The …

Content truncated to 500 words