Thematic roles such as Agent and Instrument have a long-
standing place in theories of event representation. Nonetheless,
the structure of these categories has been difficult to determine.
We investigated how instrumental events, such as someone
slicing bread with a knife, are categorized in English. Speakers
described a variety of typical and atypical instrumental events,
and we determined the similarity structure of their descriptions
using correspondence analysis. We found that events where the
instrument is an extension of an intentional agent were most
likely to elicit similar language, highlighting the importance of
agency in structuring instrumental categories.
