Field of Science

Findings: That Kind of Person

That Kind of Person is now complete. Many thanks to all who answered the call to participate.


For some time now, I have been studying the effect of context on pronoun interpretation. If words and sentences always meant what they meant regardless of context, linguistics and psycholinguistics would be much easier, and we would have much better computer translation, speech recognition, etc. Unfortunately, the same word (bank) can often mean different things in different contexts (he paddled over to the bank versus he cashed a check at the back).

Pronouns are a great guinea pig for studying the role of context, because they derive almost all their meaning from context (try to define “she” or “he” and compare it to your definition of “Martha Washington” or “George Washington”).

Great Expectations

Recently, a picture has started to emerge, at least in the case pronouns. The basic idea, due mostly to the work of Andrew Kehler at UCSD*, is that our initial interpretation of a pronoun is driven by what we think is likely to be talked about next. If this seems obvious, the dominant theory at the time Kehler started working (Centering Theory and variants) argued that our initial interpretation of the pronoun is that it refers to whatever person or thing is currently most “salient” (what counts as "salient" depends on the version of the theory) -- a hypothesis that also usually strikes folks as obvious.

Kehler's big contribution was articulating theory of discourse structure – that is, how sentences relate to one another – that can be used to fairly accurately predict what people expect to be mentioned next. (If you are interested in these issues and have a little background in linguistics, Kehler's book, Coherence, Reference, and the Theory of Grammar is fantastic.) For instance, sometimes one sentence introduces the consequence of another sentence:

(1) John frightened Bill, so he ran away.

Here, the second sentence (or, if you prefer, second clause) describes a consequence of the first sentence. Most likely "he" refers to Bill, because Bill running away would be a reasonable consequence of John frightening him. In contrast, other sentences explain the previous sentence:

(2) John frightened Bill because he is scary.

Here, "he" probably refers to John, since John being scary would be a good explanation of his frightening of Bill.

There are many other types of relationships between sentences, and they have predictable effects on pronoun interpretation. Although Kehler's theory explains a lot, it does not explain, for example, why we think Bill running away is a more likely effect of John frightening Bill than Bill running away.

The role of verbs

In two recent papers, which I discussed on this blog, my colleagues and I argued that verbs play a major role. Verbs -- specifically, the relationship between a verb and its subject and object -- provide a lot of information about events. We drew in particular on one line of theoretical work (usually called "predicate decomposition theory"), which tries to explain how verb meaning can be built out of a few constituent parts. The details aren't important here. What is important is that this theory argues that some  verbs specify who the cause of the event was. What we showed was that usually, in sentences like (2), people think the pronoun refers to the person that the verb specifies as the cause. In this case, "frighten" means something like "John caused Bill to be afraid". Remember that "he is scary" is an explanation of "John frightened Bill." Explanations usually refer to causes.

In short, by drawing on independent theories of discourse structure and verb meaning, we were able to predict very well how people will interpret pronouns in various contexts. At least, we could do so in the ones we tried -- there's a lot of work left to be done to fully flesh out this work.

The problem

I have been presenting this work for a while, and I often get the following objection: We already know that verbs can't be doing all (or even much) of the work. The real story, it was argued, is much more complex. Thinking just about the explanation sentences like (2), Pickering and Majid (2007) noted that multiple factors "affect the construction of the event representation, and it is this event representation that is used to infer the cause..." They cite experimental findings argued to show that pronoun interpretation in sentences like (2) depend in complex ways not just on the verb but on what you know about the subject and the object:
In addition, properties of the participants affect implicit causality. Changing the gender (Lafrance, Brownell, & Hahn, 1997), animacy (Corrigan, 1988, 1992), or typicality (Corrigan, 1992; Garvey et al., 1976) of the participants changes the [pronoun interpretation].
After hearing this enough times, I started what I thought would be a series of studies to look at how information about the subject and object interact with the verb in real time during sentence comprehension. This project never got off the ground because I couldn't find any such effects. That is, I have now run a number of studies where I manipulate the gender or typicality, etc., of the subject and object, and they have no effect on pronoun interpretation.

It turns out that there was some confusion in the literature. The studies that Pickering and Majid cite in the quote above mostly don't look at pronoun interpretation at all. Most look at a different task:

(3) John frightened Bill.
a. How likely is this because John is the kind of person who frightens people? 1 2 3 4 5 6 7 8 9
b. How likely is this because Bill is the kind of person people frighten? 1 2 3 4 5 6 7 8 9

Researchers look whether the answer to (a) is greater or less than the answer to (b) to decide who people think caused the event: John or Bill? Much of the literature has assumed that the answer to this question should predict what happens in pronoun sentences like (2), even though this has never been rigorously shown. (Why it hasn't been carefully tested is a bit of a mystery. It is so widely believed to be true that I suspect many folks don't realize that it hasn't been tested. It actually took me several years to pick up on this fact myself.)

I now have a long line of studies showing that there is little relationship between the two tasks. Also, although manipulating who the subject and object are affect the task in (3), I find very little evidence that it affects pronoun interpretation in (2). For instance, compare the following:

(4) a. The king frightened the page because he....
     b. The page frightened the king because he....

Everybody agrees that, in general, it is more likely that kings frighten pages than that pages frighten kings, and so if you use these sentences in (3), you get a nice effect of who the subject is. But it doesn't affect pronoun interpretation at all.

This is a serious blow to Pickering and Majid's argument. They argued that pronoun interpretation cannot be all (or mostly) about discourse structure and verb meaning because these interact in complex ways with knowledge about the subject and object (I should add: non-linguistic knowledge. It presumably is not part of the definition of king and page that kings frighten pages but not vice versa, but rather something you learn about the world). If it turns out that this is not the case, then discourse structure + verb meaning may well explain much or all of the phenomenon at hand.

That Kind of Person

That was my argument, anyway, in a paper that I have been shopping around for a couple years now. The difficulty with publishing this paper is that it makes a null argument: you can't find effects of knowledge about the subject and object on pronoun interpretation. In fact, all I can show is that the manipulations I have tried haven't worked, not that no manipulation works (you can't try everything!). So much of the review process has been reviewers suggesting additional experiments and me running them. The latest -- and I hope last -- one was That Kind of Person.

A reviewer very smartly noted that a big difference between (2) and (3) is that (3) asks about the kind of person the subject is and the kind of person the object is, whereas (2) does not. What we are manipulating in our king/page manipulation is, of course, the kind of person the subject is and the kind of person that the object is. So the reviewer suggested the following pronoun task:

(5) a. The king frightened the page because he is the kind of person that...
     b. The page frightened the king because he is the kind of person that...

The specific manipulation was one of status. It was argued in the literature that people are more likely to think that high-status folk (kings) caused the event that low-status folk (pages). This does turn out to be true if you use the task in (3), but yet again I found no effect on pronouns, either using sentences like (4) or like (5). (Sorry -- I was going to include a graph, but the results aren't formatted for graphing yet, and it's time for lunch! Maybe when the paper is published...)

Conclusions

I think the result of this work is that it suggests that we really are narrowing in on "the" theory of pronoun interpretation (though there is a lot of work left), a theory in which most of the work is done by discourse structure and verb meaning. This is pretty exciting, because it would be one of the rare cases where we have a reasonably complete theory of how context affects word meaning. It does leave open the question of what the task in (3) is measuring, and why it doesn't match what the pronoun tasks measure. That's still the sticking point in the review. I have a few new ideas, and we'll see what the reviewers say this time around.

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*Editors at newspapers and magazines usually request that, whenever you introduce a scientist in an article, you state name, institution, and scientific field. The first two are easy, but the last one is hard, particularly when you frequently write about interdisciplinary research (which I do). I wrote about Kehler in an article for Scientific American Mind a while back, and introducing him caused a long debate. His degree is in computer science, he works in a linguistics department, but his work is probably best described as psychology. So what is he?

Just another reason I prefer blogging.

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