Syntax is the grammatical structure of the sentence. In particular, it has to do with rules of how words can go together. For example, there are certain places in a sentence where a noun is
necessary, or where a verb cannot appear, etc. In English, a sentence like I saw Max's of pizza is ungrammatical, because the word of cannot appear after a possessive. All languages
have syntactic rules; all languages have constraints about how works can go together, based on what kind of word they are (noun, verb, adjective, etc.)
Plausibility, on the other hand, has to do with whether a sentence makes sense in the world we live in. A sentence like Samantha ate the airplane sounds weird, but it has no syntactic
problems (the sentence doesn't break any rules of how words go together in English). Instead, we just know that airplanes aren't things that people normally eat. Sentences can be implausible for many
reasons. Sentences can be implausible because of general world knowledge (such as the example we just saw, Samantha ate the airplane; pretty much everyone knows that airplanes aren't things
we eat; but this is still a form of "world knowledge", because we could imagine a world where this is different [e.g., a world where airplanes are made of chocolate, or a world where there are giant
airplane-eating monsters]). Or sentences can be implausible because of more specific world knowledge; for example, a sentence like Carrie Lam carried the toilet paper she had bought from the store,
and skillfully swiped her Octopus to go into the MTR station. To someone who doesn't know many details about Hong Kong, this sentence might not be implausible; but to someone who knows more details
(like the fact that Carrie Lam doesn't know how to buy toilet paper and doesn't know how to use an Octopus card) the sentence will still look implausible.
Write one example of a sentence that has a syntactic problem but is still plausible, and one example of a sentence that has perfect syntax but is implausible. Your examples can be in any
language.
There are different theories about how syntactic information and plausibility information are used by the parser when you try to understand a sentence.
- Syntax-first model (also called serial model, two-step model, or autonomous model). One possibility is that when you are understanding a sentence, the first step is to use
only syntactic information to put together the sentence structure. i.e., with each word you read, you check what kind of word it is (is this a noun? a verb? a preposition?) and use that
information to figure out how it fits into the sentence structure. Syntactic processing is something rapid and language-specific. After you have put together the sentence and figured out what it
means, then you can consider your real-world knowledge and notice if the meaning of the sentence sounds plausible or not. But putting the sentence structure together based on syntax must
be the first step, because of course if you don't have a sentence structure then you can't put together what the meaning of the sentence is. (This model is sometimes called the "two-step" model or
"serial" model because syntactic information is used first and other information is used later; it's also sometimes called the "autonomous" model because syntax information is processed
autonomously, independent of plausibility or other kinds of information.)
- Interactive model (also called one-step model). The other possibility is that your parser uses all available kinds of information immediately, as soon as possible. I.e., there is
no "autonomous" first step where the sentence is put together based only on syntax. Instead, every time you read another word, you immediately use any information you can think of (including syntax
information, such as whether the word is a noun or a verb, but also including plausibility information such as whether the meaning of the sentence would make sense if you integrate this word in a
certain way) to help you decide how this word will fit into the sentence.
Note that the claim of the syntax-first model is not that we never care about plausibility; it's just that plausibility information is used later than syntactic information; i.e., there is some early
moment during sentence processing (possibly so early and short-lived that we don't even consciously notice it) in which we parse based on syntax alone. Therefore, merely observing that you pay attention
to the plausibility of a sentence is not evidence against the syntax-first model; it's possible that the stage at which you are paying attention to that information occurs later than the syntax-only
stage (and that's why this is a question that needs to be answered with psycholinguistic methods).
Which of these models do you think is right? Provide some argument to justify your choice. (There is no right or wrong answer for this, and your response is not graded; I just want you to
think about the problem and make an argument.)
One way this question has been tested is by seeing if plausibility information can help people avoid a garden path effect.
Recall that the garden path effect occurs when someone misinterprets a sentence and later has to correct their understanding. For example, in the sentences below (repeated from the previous part of this
module), people will read would more slowly in the reduced sentence than in the full sentence, because in the reduced sentence they initially
misunderstand The professional agent knew the actress as being a simple sentence with "the actress" as the object.
- Full: The professional agent knew that the actress would be arriving tomorrow morning.
- Reduced: The professional agent knew the actress would be arriving tomorrow morning.
But let's think about another example:
- Full: The witness that was examined by the lawyer was unreliable.
- Reduced: The witness examined by the lawyer was unreliable.
Can you figure out where a garden path effect might occur in a pair of sentences like these?
When someone reads The witness examined..., they might expect there will be another noun after that (the witness examined SOMETHING). So they might be surprised when they read by. When
they read by they need to realize that the witness didn't actually examine something; actually the witness WAS EXAMINED by a lawyer. Therefore, people might read by more slowly in the
reduced sentence than they do in the full sentence; that's a garden path effect.
Now let's try a slightly different version of this example:
- Full: The evidence that was examined by the lawyer was unreliable.
- Reduced: The evidence examined by the lawyer was unreliable.
What's different about this second example? Is there any reason you think the results for this one (the evidence examined...) might be different than the results for the previous one
(the witness examined...)?
The key difference in the previous example is that the word evidence is inanimate: evidence does not usually examine things. So when someone reads The evidence examined..., they
might think, "Evidence can't examine things... so I should assume that this sentence means 'the evidence THAT WAS examined...'". If they think that, they will not be surprised to read by next.
This is a classical way to test whether the parser is interactive or autonomous. If the parser is autonomous, it will only pay attention to syntax first: "the evidence" is a noun and "examined" is a verb,
so the parser will assume that this is a simple sentence where "the evidence" is the subject and "examined" is the verb, and the parser will expect an object noun next. If that happens, there will be a
garden path effect when people read by in the reduced sentence.
On the other hand, if the parser is interactive, the plausibility information will "protect" people from having a garden path effect. When they read The evidence examined..., they will use
the plausibility information to know that "the evidence" is probably not actually the subject of the sentence, because they know evidence doesn't usually examine stuff. Then they won't be surprised when
they read by, so there will not be a garden path effect.
In fact, in experiments about these kinds of examples in English, it usually has been observed that sentences like The evidence examined by... don't trigger a garden path effect. These results
suggest that the parser might be interactive.
I would like you to browse a paper describing an experiment testing this question in Chinese: PengLiu1993.pdf
Briefly explain (in about 250 words or less) what kinds of sentences the authors used in Experiment 1 to test interactivity, what they
found, and whether their results support an interactive model or an autonomous model of sentence understanding. (You can ignore Experiment 2). You need to clearly explain what their sentences
were like and how they examine interactivity, like I did above; don't just repeat the names of their conditions. (You should explain the paper such that a person who has not read the paper can understand
what you're talking about, so if you just say e.g. "plausible sentence" and "disambiguating word" and stuff like that, your explanation will not be clear.) As always, it's fine to read and discuss this
paper together with classmates. You don't need to read and understand every word; you just need to look through the paper enough to understand what they did and find the information you need to address
the question. If you can't read Chinese and don't have classmates to discuss this paper with, you can replace this with an alternative paper on a similar topic in English or some other language.