Field of Science

Cognitive Science, April 2010

This week I was tasked by the lab to check the last years' worth (or so) of issues of Cognitive Science and see what papers might be of interest to folks in the lab (other people are covering other journals). There of course many good papers not on the list below; I focused largely on the psycholinguistics articles. There are a lot of articles, so I'm going to be breaking up issues into separate posts.

Fair warning: my discussion of these articles is brief and so somewhat technical.

April 2010

Szymanik & Zajenkowski. Comprehension of simple quantifiers: empirical evaluation of a computational model.

Different quantifiers seem to require different amounts of computation. Formal logic suggests that checking the truth of Some of the cars are blue simply requires checking whether at least one car is blue (or failing to find any). Most of the cars are blue probably requires something like finding out how many cars is 1/2 of the cars and checking to see if at least more than  that are. That's harder.

S&Z had people evaluate the truth value of sentences like those in the examples. People were slower for the "harder" quantifiers. This suggests people are actually running through something like the formal math theorists use to describe quantifiers.

The only odd thing about the results is a ton of research (e.g., Bott & Noveck) has suggested that evaluating sentences with some can be very slow, presumably because it involves a scalar implicature, whereas in the study some was one of the fastest quantifiers. This either suggests that for some reason people weren't computing implicatures in their study or that the other quantifiers were really slow (or that Polish, the language they used, is just different).

Matthews & Bannard, Children's production of unfamiliar word sequences is predicted by positional variability and latent classes in a large sample of child-directed speech.

Two- and three-year olds were asked to repeat back four-word sequences. Several things were varied, such as how predictable the final word was based on the first three in the sequence sequence (e.g., jelly probably commonly appears after peanut butter and ... ) and whether the words that do commonly appear as the fourth word in such a sequence are semantically related (e.g., pretty much everything following I drive a ... is going to be some kind of vehicle).

Importantly, in the actual sequences presented to the children, the final word was one that hardly ever appears in that sequence (e.g., I hate green boxes). Kids were better at repeating the sequences when (1) entropy on the 4th word was high (e.g., many different words commonly follow the first three in the sequence, as in I drive a rather than peanut butter and), and when most words that typically appear in that 4th position are semantically related (I drive a truck/car/bus/Toyota/Ford). 

The authors (tentatively) suggest that such results are predicted by theories on which young children's grammars are very item-specific, involving many narrow sentence templates (I drive a + Vehicle), rather than theories on which young children's grammars involve broad abstract categories (e.g., Noun + Verb).

However, my labmate and collaborator Timothy O'Donnell has been working on a computational model that involves abstract grammatical categories but nonetheless stores high-frequency constructions (which has been allowed but not specifically explained on many grammatical theories such as Pinker's Words & Rules theory that are the traditional alternatives to item-based theories). One consequence of his model is that if a particular construction appears very frequently with little variation (peanut butter and jelly; 653,000 hits on Google), the model finds slight alternatives to that construction (peanut butter and toast; 120,000 hits on Google) extremely unlikely.

Casasanto, Fotakopoulou & Boroditsky. Space and time in the child's mind: Evidence for a cross-dimensional asymmetry.

4-5 year-olds and 9-10 year-olds watched movies of two animals traveling along parallel paths for different distances or durations and judged the which one went longer temporally or spatially. As has been previously shown in adults, the children's judgments of temporal length were affected by spatial length (e.g., if animal A went farther than B but in a shorter amount of time, children sometimes erroneously said A took the most time) more than judgments of spatial length were affected by temporal length (e.g., if animal A went farther than B but in less time, children were not as likely to be confused about when animal went the farthest).

One obvious confound, which the authors consider, is that the stimuli stayed on the screen until the children responded, which meant that information about physical distance was available at response time, but children had to remember the duration information. The authors point to a previous study with adults that controlled for this confound and got the same results, but they have not yet run that version with children (since I haven't read the study they refer to and the method isn't described, I can't really comment).

These results are taken as evidence of a theory on which our notion of time is dependent on our representations of space, but not vice versa.

Fay, Garrod, Roberts & Swoboda. The interactive evolution of human communication systems.

People played what amounted to repeated games of Pictionary. The games were played over and over with the same words, and the question was how the pictorial representations changed over repeated games. Participants were assigned either in pairs or communities of 8. The pairs played against each other only. In the communities, games were still played in pairs, but each person played first against one member of the community, then against another, and so on until they had played with everyone.

The people in the pairs condition rapidly created abstract visual symbols for the different target words, as has happened in previous research. What was interesting was that in the communities condition, participants also created similarly abstract symbols that were rapidly shared throughout the community, such that participants who had never played against one another could communicate with abstract symbols that they had each learned from others.

The study is meant to be a model of vocabulary development and dispersal, and it certainly made for a good read (I've been a fan of Garrod's work in other contexts as well). I don't know much about theories of language evolution, so it's difficult for me to say what the theoretical impact of this work is. One obvious question is whether it matters that people in a single community know they are in a single community. That is, did they continue to use the abstract symbols they'd learned because they reasonably thought the other person might know it, or was it instinct after having used that symbol many times?

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