The “Gavagai” problem How do we learn new words? What is the speaker naming?

Words / Referents How do kids extend words to classes of objects? –Start with 1 referent –Generalize within one month of acquisition –Sometimes overextend

The benefits of assumptions whole object: new words apply to the whole object taxonomic: labels apply to categories, not temporary co-occurrences of two features mutual exclusivity: new words cannot apply to the something that’s already named type: words refer to classes of objects

Categories How we categorize the world is NOT ARBITRARY: –Determined in part by: how we perceive the structure of the world cognitive economy –Semantic memory is a trade-off between economy and informativeness dog concept legumes armchair

Category Levels Superordinate Categories: –mammal, animal, animate thing, object Basic Level Categories: –dog Subordinate Categories: –terrier, rottweiler, alsatian

Basic-Level Categories (Rosch et al. 1976) Basic-levels categories are cognitively primary –Listing attributes is easy –Children acquire first –Fastest naming times –Most likely to be used spontaneously by adults –Fast semantic verification times

Semantic Verification Tasks (Collins and Quillan, 1969) Present subjects with simple “facts”. They press buttons if T/F. Measure reaction times: –A robin is a robin (baseline measure) –A robin is a bird – slightly slower –A robin is an animal – even slower –*A robin is a fish - FALSE –*A robin is a fruit – FALSE, and fast response!

Why not the other levels? Superordinate: –I put the piece of furniture by the wall decoration on the floor covering… Subordinate: –Yesterday, I was meandering on the Mix-well cement walkway near the Sycamore tree when a sparrow landed on my forearm.

One major problem: Frequency is often a confounding factor! –“bird” and “robin” co-occur more often than “bird” and “animal” –Some words that aren’t technically as related act as if they were! “Cow” and “mammal” should be more closely related, but people are quicker to say that a “cow” is an “animal”