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Syntax, Psychology of
Entry by Matthew W. Wagers for SAGE Encyclopedia of Theory in Psychology (2015)
Syntax is an area of linguistic theory that attempts to understand how larger compositional
objects, like phrases and sentences, are put together from smaller, memorized pieces, like words.
Most narrowly, it is responsible for explaining both why words occur in the orders and forms
they do and how such strings of words can give rise to the meanings that they do. Beginning
with the generative grammar tradition inaugurated by Noam Chomsky and colleagues, syntactic
theory has pursued a broader goal: To provide this explanation in a way that would further allow
an understanding of the variation among the world’s languages. It thus emphasizes explanations
of particular languages that draw from a common set of features and operations; in doing so,
syntax, along with allied theories like phonology and semantics, aims to characterize the building
blocks of the universal ability to acquire and use language.
Elements of a Syntactic Theory
There is a wide range of formal syntactic theories, but they all, in one way or another, posit a
system of mental representations to mediate between form and meaning. These representations
identify dependencies between words and groups of words called “constituents”. Take sentence
(i) as an example:
(i)
The clown squirted the child with the flower.
Sentence (i) is ambiguous – it has two meanings: Either the clown used the flower to squirt the
child (instrument meaning), or it is a child holding flowers whom the clown squirted (modifier
meaning). The commonest way of accounting for the ambiguity is to say that there are two
distinct syntactic representations, each corresponding to one string-to-meaning mapping. These
two representations share a grouping together of the words “with the flower” to form a single
constituent as indicated in (ii) with the brackets labeled “PP” (for “prepositional phrase”).
(ii)
… with the flower … à [ with the flower ]PP
How they differ is in whether this PP first combines with “child” before it combines with the
verb, (iii), giving rise to the modifier meaning; or whether the verb first combines with “child”,
to the exclusion of PP, (iv), corresponding to the instrument meaning.
(iii)
Partial syntactic representation for modifier meaning of (i)
… squirted the child PP … à … squirted [ the child PP ]NP
… squirted NP … à … [ squirted NP ]VP
(iv)
Partial syntactic representation for instrument meaning of (i)
… squirted [ the child ]NP PP … à … [ squirted NP ]VP PP …
… VP PP … à … [ VP PP ]VP
This example embodies many core properties of syntactic representations shared across
different theories. Firstly, they consist of ordered groupings. Although theories appeal to
different formal devices to capture ordering, all theories have a way of doing so. For example, in
Head-driven Phrase Structure Grammar, constituency is reflected in the way in which labeled
feature structures can nest within one another. Thus, the VP constituent in (iii) is represented by
a set of features. One feature, DTRS (“daughters”), is a list that includes “squirt” and NP; NP, in
turn, is a feature set whose DTRS feature lists “child” and PP; etc. I n other theories, like
Combinatory Categorial Grammar or Minimalist Grammar, order is captured by the sequence of
steps – called a derivation – by which groups of words can be combined together and relabeled
(as in (ii)-(iv) above).
Constituency is one key way by which syntactic representations encode dependencies. In
(iii), “with the flower” modifies “child” because the representation groups those two units
together. In Minimalism, this grouping relationship is known as Merge. Thus, the example in
(v) is unambiguous, in part, because there is no legal sequence of Merge applications that can
group PP with the verb “squirt”.
(v)
[ The child [ with the flowers ]PP ]NP was squirted by the clown.
The successive application of Merge, by which a string can be exhaustively parsed and labeled,
is believed by some to be a core, and perhaps distinctive, property of natural language.
Secondly, constituents usually have a distinguished member, called the head. Properties
of the head determine the nature of the constituent as a whole. In (v), the word “child” is the
head of an entire NP, and the fact that “child” is singular means that the entire NP is singular.
Thus the form of the verb is “was” and not “were’, even though the verb is immediately adjacent
to the plural noun “flowers”. Non-head members of a constituent are of different types. In the
examples above, PP has a modifier function and is called an adjunct. The other crucial non-head
constituents are: the complement, which the head must combine with first and which (usually)
supplies an argument to the function denoted by the head; and the specifier, which combines
after the complement.
The organization of words into groups according to a particular order, with particular
features and labels, provides a powerful and general means for describing relationships in natural
language. These relationships are characterized by their locality: Words can influence the form
or interpretation of other words or phrases if they are grouped closely-enough together. Thus, in
(v), the noun “flowers”cannot influence agreement with the verb because it was combined with
other words first. However, there are some relationships that, at least on the surface, are non-
local. For example, in (vi), the constituent “the child’ is the subject of –and closest to- the verb
“was”, yet it is interpreted as one of the arguments of “eat”. [Notice that (vi) is essentially
synonymous with “It was likely that the child ate noodles.”]
(vi)
The child was likely ___ to have eaten noodles.
Similarly, in (viii), the phrase “which noodles”is interpreted as if it were the complement of the
verb “prefers” despite the many other words that intervene.
(viii)
Which noodles do you think the child prefers ___?
The dependencies in (vi)-(viii), between the pronounced position of a phrase (underlined) and its
site of interpretation (marked with an underscore), illustrate varieties of non-locality. Syntactic
theories have responded to non-locality by enriching the basic constituent representation in a
variety of ways – most famously, by postulating a movement transformation that can re-arrange
constituents established initially by Merge, as in Minimalism and earlier versions of that theory.
“Psychological Reality” of Syntactic Theory
Speakers of a language are able to produce intuitions about whether sentences or parts of
sentences belong to their language, a behavior typically elicited as an acceptability judgment (“Is
this sentence acceptable to you?”). Syntactic theories are primarily formulated so that clearlyacceptable sentences can systematically and mechanically be assigned one status –
“‘grammatical” – while the unacceptable sentences are assigned another status –
“ungrammatical”. The notion of grammaticality or grammaticalness is probably one of degrees,
and most theories possess the ability to make such gradient distinctions.
Since the beginning of generative grammar, questions have arisen about the
psychological reality of representations arrived at on the basis of acceptability judgments. The
term is itself tendentious, because acceptability judgments are a kind of behavior, and thus a
systematic theory of them can fairly be called “psychological” by itself. More precise questions
to ask are: To what extent, if any, do other measures cross-validate the representations proposed
by syntactic theories? How are those representations used in language comprehension and
production?
Early research, beginning in the 1960s, used (mostly) untimed tasks like conditional free
recall or “perceived relatedness” between words. By demonstrating asymmetries between which
words were most readily related or most likely to be recalled, these measures cross-validated the
existence of constituent structure. Another technique, known as “click dislocation,” involved
having experimental participants identify the position of a noise burst spliced into an auditory
sentence stimulus. Respondents tended to recall the burst as being closer to major constituent
boundaries than it actually was. Finally, in language production, the analysis of speech errors
showed that these slips of the tongue were closely regulated by constituent groupings.
In the 1960s, the Derivational Theory of Complexity arose as a prominent early
hypothesis linking the difficulty of processing a sentence to the number of steps in its derivation.
Although initially successful at predicting performance in some tasks, like sentence matching or
verification, it did not fare well for other tasks and sentence types. The ultimate insufficiency of
the Derivational Theory of Complexity came to be regarded as an indictment of derivational
theories like Transformational Grammar. It would be more accurate to portray it as indicative of
the then-inchoate understanding of how factors other than syntactic representation affect
language processing – factors such as ambiguity, frequency of use, and working memory. These
issues came to the forefront of research into language production and comprehension, where they
remain today.
At the Interface With Language Processing
Ambiguity has been a particularly important theme at the interface of language processing and
syntax. How do speakers, when confronted with an ambiguous sentence like (i), choose a
meaning in context? There are three main lines of thought: The first, most closely affiliated with
the Garden Path Theory, holds that properties of the syntactic representation affect initial
preferences. This theory predicts that speakers initially resolve ambiguities toward simpler
representations: fewer constituents, shorter derivations, complements preferred over adjuncts,
etc. The second view holds that speakers’ experience with language shapes their preferences,
such that ambiguities are resolved in a way consistent with the most-frequently-used
representations. The third view holds that the syntactic representation is selected according to
the meaning most appropriate in the current context. These viewpoints are not mutually
incompatible, and no one theory has come to conclusively dominate the others empirically.
Instead, they have revealed an intricate interplay of different information sources in language
processing, each with characteristic time-courses and mechanisms.
One area of convergence between theories of syntax and of language processing
recognizes the richness of the lexicon. Evidence abounds from syntactic analysis and languageprocessing experiments that lexical entries – what is memorized about specific words – contain
rich, granular information about syntactic combination. As an example, consider that the English
adjective “fond” requires a complement 100% of the time, but that the adjective “eager’ only
combines with a complement sometimes. Speakers track such facts about particular words and
use them in language processing. In production, for example, speakers tend to reuse syntactic
representations that they have been exposed to in a specific instance – a phenomenon called
syntactic priming. However, priming is strongest when not only an identical structure can be re-
used but also with the same word; in this way, speakers seem to anchor particular syntactic
representations to specific words. Not all syntactic proclivities are equal, however. Although
speakers track head-complement combinations closely, they don’t seem to pay as close attention
to adjunct combinations. The theory of Construction Grammar illustrates a more-drastic claim
about the lexicalization of syntactic processes: Syntactic generalizations are held to be more
piecewise than in other theories and to inhere in specific words or multi-word combinations.
Finally, the processing of non-local dependencies, like (vi)-(vii), has been a core area of
theoretical development. Because they involve relationships between words that are far apart,
they have been linked with questions about prediction and working memory: e.g., whether there
is language-specific working memory, what its span is, how correct constituents are retrieved
from memory, etc. Moreover, there are curious restrictions, dubbed island constraints, that
block the formation of some conceivable dependencies. For example, (viii) is acceptable in
English, but (ix) is not.
(viii)
Which flowers are you fond of ___ ?
(ix)
Which flowers would the clown’s fondness for ___ surprise me?
There has been debate over whether syntactic theory should capture the unacceptability of
sentences like (ix), or whether it is best explained by non-syntactic means, like conditions on use
or facts about working memory. Although some island constraints are quite general across
constructions and languages, others are more heterogeneous, suggesting that the ultimate theory
will identify multiple explanations. However, this line of investigation – which has been
informed by research in Cognitive Linguistics, by language processing, and by semantics and
pragmatics – remains active and fruitful. Moreover, it illustrates how syntactic theory is a nexus
for multiple domains of psychological inquiry.
2000 words -- January, 2015
Recommended Readings
Frank,R.(2002).Phrasestructurecompositionandsyntacticdependencies.Cambridge,MA:
MITPress.
Frazier,L.&Clifton,C.(1996).Construal.Cambridge,MA:MITPress.
Levelt,W.J.M.(1974).FormalGrammarsinLinguisticsandPsycholinguistics(vol.III).The
Hague:Mouton.
Sag,I.A.,Wasow,T.,andBender,E.M.(2003).Syntactictheory:AformalIntroduction.Palo
Alto,CA:CSLI.
Townsend,D.&Bever,T.(2001).Sentencecomprehension.Cambridge,MA:MITPress.