Similar, and similar concepts.

This paper analyzes English symmetrical predicates such as collide and match. Its point of departure is an analysis of the concept 'similar' from Tversky (1977) that appears to show that similarity is psychologically asymmetrical. One basis for this claim from Tversky is that the sentences North Korea is similar to Red China and Red China is similar to North Korea are assessed as differing in meaning by experimental subjects; this seems to imply that the symmetrical entailment (R x, y <--> R y, x) fails for this concept. Five experiments are presented that show: (1) the apparent asymmetry of similar is reproduced for 20 predicates that are intuitively thought to be symmetrical, including equal and identical; (2) unique linguistic-interpretative properties hold for these symmetrical words, such as reciprocal interpretation when they appear intransitively, for example, North Korea and Red China are similar; (3) the asymmetrical interpretation of subject-complement constructions containing the symmetrical words is a consequence of general linguistic-interpretive principles. On the basis of the experimental findings, we offer an analysis of symmetrical predication. One major claim of the analysis is that symmetry is a property of lexical items and has no special syntax, that is, that John meets is semantically but not syntactically anomalous. A second claim is that the structural positioning of noun phrases in sentences containing symmetricals--rather than inherent semantic properties of the noun phrases themselves--sets their status as Figure and Ground (as described by Talmy, 1985) or Variant and Referent (as described by Tversky, 1977) in the comparison, even if the nouns are nonsense items. Finally, the behavior of symmetrical predicates is shown to vary as a function of their differing lexical class assignments and collateral semantic designations, such as activity versus state. Most generally, it is claimed that a deeper understanding of symmetrical terms comes from analyzing the semantics of syntactic structures in which they appear.