What kind of concepts need language?

The question addressed in this paper is whether the language faculty provides new possibilities for concepts. Drawing on work from Hinzen and Sheehan (2013) and others, the claim is that I-language allows humans to see resemblances among events that are similar in only an abstract way mediated by their linguistic description, such as the hierarchical form that unites the class of events in which a boy chases a dog, not vice-versa. Experimental data are presented from five preliminary studies. These include a study of 61 preschool-aged children in an act-out procedure with and without verbal description, and a second with 63 adults in a picture choice procedure under conditions of verbal versus rhythmic shadowing. The methodological difficulties are discussed, particularly the use of rhythmic shadowing as an adequate control. Three further studies are reported that use adult participants in an implicit concept formation paradigm in an eyetracker, using a dual-task procedure with only verbal shadowing. These studies have the goal of discovering whether verbal shadowing selectively impairs certain abstract concepts and not others. Together the results suggest that verbal shadowing is selectively disruptive of the recognition of similarity across perceptually diverse events sharing a propositional description, but not of the formation of other abstract concepts.