A Symposium on The Diversity of Conceptual Combination Fintan Costello, Zach Estes, Christina Gagné, Ed Wisniewski.  Four speakers: 15 min. talks + 5 min. questions. 10 min. discussion at the end.

What is Conceptual Combination? Putting two existing concepts together in some way to produce a new “combined concept”. However, we don’t have direct access to concepts. We assume that conceptual combination is seen when people are asked to interpret a noun-noun compound phrase (e.g. what is a “dog hotel”?) –We are mainly interested in how the noun constituents of a compound (“dog” and “hotel”) are put together to produce an interpretation for the compound. –Other aspects are also of interest: property inference (what might be found in a “dog hotel”?), classification (how do we identify places that might be “dog hotels”), typicality judgements, etc.

How do Concepts Combine? Three Main Types of Combination Relational compounds require us to assert a relation between the two combining concepts (e.g. a “mountain cabin” is a cabin located in the mountains). Property-transfer compounds require us take a property from one concept and apply it to the other (a “cactus fish” is a fish covered in prickly needles). Conjunctive compounds require us to do something like set intersection on the combining concepts (a “pet lobster” is a lobster that is also a pet).

Other Examples of Combination Combinations involving relation & property-transfer, e.g. “shovel bird”: a bird that has a flat, wide beak like a shovel, for digging worms. relation “Exocentric” combinations, which refer to external concepts, e.g. “sea camel”: a fish with a hump on its back (again, this can be both relational and property transfer; this can involve the construal of one concept as referring to an associated concept; sea is construed as referring to fish ) Ambiguous examples, e.g. “camera phone”: is it a phone that is a camera (conjunctive), a phone with a camera as a part (relation), or that has properties of a camera (property)? property

Questions to be Asked Why are there different types of combination? Are all types of combination equally important? There are many, quite different, theories of combination: –Gagne’s CARIN model focuses on relational combinations and sees property combinations as relatively unimportant; –Este’s account focuses primarily on property combinations; –Wisniewski gives two separate mechanisms, one for relational combinations and one for property combinations; –Myself & Mark Keane attempt to give a single constraint-based mechanism that explains all the different types of combination. Answering questions about the distinction between the different combination types may allow us to reconcile these different theories.

Constraint Theory (pragmatics of combination) A listener trying to understand a novel phrase must construct a combined concept to represent that phrase. To guide construction of this concept, the listener assumes that the speaker, in uttering the phrase, is trying their best to indicate one particular combined concept (the speaker is cooperating, a lá Grice). Three constraints of plausibility, diagnosticity, and informativeness follow from this assumption (described next). By following these constraints the listener can construct the correct concept as intended by the speaker. (We provide a constraint-satisfaction algorithm which efficiently constructs combined concepts using these three constraints.)

Constraint-Guided Concept Combination 1) Since the speaker is cooperating, the intended combined concept is something the listener already more-or-less knows (otherwise the speaker wouldn’t use a short compound phrase) Thus the new combined concept must describe something plausible (similar to things the listener has seen before). 2) Since the speaker is cooperating, the intended combined concept is one best identified by the two words in the phrase (otherwise the speaker would have selected other words) Thus the new combined concept must contain some properties which are best identified by (are diagnostic of) each word in the phrase being interpreted.

3) Since the speaker is cooperating, the intended combination is one for which both words in the phrase are necessary (otherwise the speaker would have used fewer words). The new combined concept must be more informative than either of the constituent words in that phrase on their own. For example, consider “shovel bird”: a bird that has a flat, wide beak like a shovel, for digging worms. Constraint-Guided Concept Combination (cont.) Diagnostic properties of “shovel” Description of something plausible New information

Assessment of this Theory In our account the different combination types happen because the proposed constraints can be satisfied in various different ways. However, our theory says little (so far!) about observed differences between combination types: for example, property combinations are influenced by the similarity of the combining concepts, while relational combinations are not. In simulations the constraint-satisfaction algorithm produces the different combination types (relational, property, conjunctive etc.). Studies show that people reliably use diagnostic properties in property-transfer combinations (and possibly in exocentric combinations like “sea camel”).

Addressing the Questions: Property versus Relational combinations? The differences between current theories are related to the distinction between property and relational combinations. A better understanding of this distinction is required. The line between “property interpretations” and “relational interpretations” is unclear. Consider –What is a “cactus fish”? A fish covered in prickly needles; this intrepretation involves property transfer from cactus to fish. –What is a “needle fish”? A fish covered in prickly needles; this intrepretation involves a relation between needle and fish. To progress, we need to explain how relations are ‘made out of’ properties, and properties are ‘made of’ relations.