Syntactic ambiguity, also known as structural ambiguity, [1] amphiboly, or amphibology, is characterized by the potential for a sentence to yield multiple interpretations due to its ambiguous syntax. This form of ambiguity is not derived from the varied meanings of individual words but rather from the relationships among words and clauses within a sentence, concealing interpretations beneath the word order. Consequently, a sentence presents as syntactically ambiguous when it permits reasonable derivation of several possible grammatical structures by an observer.
In jurisprudence, the interpretation of syntactically ambiguous phrases in statutory texts or contracts may be done by courts. Occasionally, claims based on highly improbable interpretations of such ambiguities are dismissed as being frivolous litigation and without merit.[ citation needed ] The term parse forest refers to the collection of all possible syntactic structures, known as parse trees , that can represent the ambiguous sentence's meanings. [2] [3] The task of clarifying which meaning is actually intended from among the possibilities is known as syntactic disambiguation. [4]
A globally ambiguous sentence is one that has at least two distinct interpretations and where reading the entire sentence does not resolve the ambiguity. Globally ambiguous sentences exist where no feature of the representation (i.e. word order) distinguishes the possible distinct interpretations. Global ambiguities are often unnoticed because readers tend to choose the interpretation they understand to be more probable. One example of a global ambiguity is "The woman held the baby in the green blanket." In this example, the baby, incidentally wrapped in the green blanket, is being held by the woman, or the woman is using the green blanket as an instrument to hold the baby, or the woman is wrapped in the green blanket and holding the baby.
A locally ambiguous sentence is a sentence that contains an ambiguous phrase but has only one interpretation. [5] The ambiguity in a locally ambiguous sentence briefly stays and is resolved, i.e., disambiguated, by the end of the speech. Sometimes, local ambiguities can result in "garden path" sentences, in which a structurally correct sentence is difficult to interpret because one interpretation of the ambiguous region is not the one that makes most sense.
Aristotle writes about an influence of ambiguities on arguments and also about this influence depending on either combination or division of words:
... if one combines the words 'to write-while-not-writing': for then it means, that he has the power to write and not to write at once; whereas if one does not combine them, it means that when he is not writing he has the power to write.
— Aristotle, Sophistical refutations, Book I, Part 4
Newspaper headlines are written in a telegraphic style (headlinese) which often omits the copula, creating syntactic ambiguity. A common form is the garden path type. The name crash blossoms was proposed for these ambiguous headlines by Danny Bloom in the Testy Copy Editors discussion group in August 2009. He based this on the headline "Violinist linked to JAL crash blossoms" that Mike O'Connell had posted, asking what such a headline could be called. [8] The Columbia Journalism Review regularly reprints such headlines in its "The Lower Case" column, and has collected them in the anthologies "Squad Helps Dog Bite Victim" [9] and "Red Tape Holds Up New Bridge". [10] Language Log also has an extensive archive of crash blossoms, for example "Infant Pulled from Wrecked Car Involved in Short Police Pursuit". [11]
Many purported crash blossoms are apocryphal or recycled. [12] One celebrated one from World War I is "French push bottles up German rear"; [13] life imitated art in the Second World War headline "Eighth Army Push Bottles Up Germans". [14]
Syntactic or structural ambiguities are frequently found in humour and advertising. One enduring joke using an ambiguous modifier is a quip spoken by Groucho Marx in the 1930 film Animal Crackers: "I shot an elephant in my pajamas. How he got into my pajamas I don't know." Another sentence, which emerged from early 1960s machine translation research, is "Time flies like an arrow; fruit flies like a banana".
Significantly enough, structural ambiguities may also be intentionally created when one understands the kinds of syntactic structures that will lead to ambiguity; however, for the respective interpretations to work, they must be compatible with semantic and pragmatic contextual factors. [1]
In syntactic ambiguity, the same sequence of words is interpreted as having different syntactic structures. In contrast, in semantic ambiguity the structure remains the same, but the individual words are interpreted differently. [15] [16] Controlled natural languages are often designed to be unambiguous so that they can be parsed into a logical form. [17]
Immanuel Kant employs the term "amphiboly" in a sense of his own, as he has done in the case of other philosophical words. He means it as a confusion of pure understanding with perceived experience, and an attribution to the latter of what belongs only to the former. [18]
Competition-based models hold that differing syntactic analyses rival each other when syntactic ambiguities are resolved. If probability and language constraints offer similar support for each one, especially strong competition occurs. On the other hand, when constraints support one analysis over the other, competition is weak and processing is easy. After van Gompel et al.'s experiments (2005), the reanalysis model has become favoured over competition-based models. [19] Convincing evidence against competition-based models includes the fact that globally ambiguous sentences are easier to process than disambiguated (clearer) sentences, showing that the analyses do not compete against each other in the former. Plausibility tends to strengthen one analysis and eliminate rivalry. However, the model has not been completely rejected. Some theories claim that competition makes processing difficult, if only briefly. [19]
According to the reanalysis model, processing is hard once the reader has realised that their analysis is false (with respect to the already adopted syntactic structure) and he or she must then return and recheck the structure. Most reanalysis models, like the unrestricted race model, work in series, which implies that only one analysis can be supported at a time.
Consider the following statements:
Research supports the reanalysis model as the most likely reason for why interpreting these ambiguous sentences is hard. [19] Results of many experiments tracking the eye-movements of subjects have demonstrated that it is just as hard to process a persistently ambiguous sentence (1) as an unambiguous sentence (2 and 3) because information before the ambiguity only weakly leans towards each possible syntax. [19]
The unrestricted race model states that analysis is affected before the introduction of ambiguity and affects which meaning is used (based on probability) before multiple analyses can be introduced. Gompel and Pickering plainly refer to the unrestricted race model as a two-stage reanalysis model. Unlike constraint-based theories, only one analysis can be made at any one time. Thus, reanalysis may sometimes be necessary if information following the first analysis proves it wrong. [19]
However, the name "unrestricted race" comes directly from its properties taken from the constraint-based models. As in constraint-based theories, any source of information can support the different analyses of an ambiguous structure; thus the name. In the model, the other possible structures of an ambiguous sentence compete in a race, with the structure that is constructed fastest being used. The more such an analysis is supported, and the stronger the support is, the more likely this one will be made first. [20]
Consider the following statements:
Research showed that people took less time to read persistently ambiguous sentences (sentence 1) than temporarily ambiguous sentences that were clarified later (sentences 2 and 3). In sentences 2 and 3, the reflexive pronouns “himself” and “herself” clarify that “who scratched” is modifying the son and the princess respectively. Thus, the readers are forced to reanalyse and their reading times will therefore rise. In sentence 1, however, the ambiguity of the reflexive pronoun “herself” fits both the maid and the princess. This means the readers do not have to reanalyse. Thus, ambiguous sentences will take a shorter time to read compared to clarified ones. [21]
This is called the underspecification account [22] as readers do not stick to a meaning when not provided with clarifying words. The reader understands someone scratched herself but does not seek to determine whether it was the maid or the princess. This is also known as the “good-enough” approach to understanding language. [23]
The good-enough approach to understanding language claims that representations of meaning are usually incomplete and language processing only partial. A good-enough interpretation may occur when such a representation is not robust, supported by context, or both and must handle potentially distracting information. Thus, such information is clipped for successful understanding [23]
Children interpret ambiguous sentences differently from adults due to lack of experience. Children have not yet learned how the environment and contextual clues can suggest a certain interpretation of a sentence. They have also not yet developed the ability to acknowledge that ambiguous words and phrases can be interpreted multiple ways. [24] As children read and interpret syntactically ambiguous sentences, the speed at which initial syntactic commitments are made is lower in children than in adults. Furthermore, children appear to be less skilled at directing their attention back to the part of the sentence that is most informative in terms of aiding reanalysis. [25] Other evidence attributes differences in interpreting ambiguous sentences to working memory span. While adults tend to have a higher working memory span, they sometimes spend more time resolving the ambiguity but tend to be more accurate in their final interpretation. Children, in contrast, can decide quickly on an interpretation because they consider only the interpretations their working memory can hold. [26]
For low reading span adults who had the worst verbal working memory, they took longer to process the sentences with the reduced relative clause compared to the relative clause and had similar times from inanimate or animate subjects. For high reading span subjects who had the best verbal working memory, they were overall faster than the low reading span subjects. Within the high reading span subjects, however, they responded faster to inanimate subjects and took longer to respond to animate subjects. This was because the animate subjects had a greater propensity to create a garden path sentence because of (not despite) greater verbal working memory. This suggested that since the low reading span subjects had less cognitive resources, only syntactic cues could be processed while high reading span subjects had more cognitive resources and could thus get tripped up with the garden path sentence. [26] [27]
Ambiguity is the type of meaning in which a phrase, statement, or resolution is not explicitly defined, making for several interpretations; others describe it as a concept or statement that has no real reference. A common aspect of ambiguity is uncertainty. It is thus an attribute of any idea or statement whose intended meaning cannot be definitively resolved, according to a rule or process with a finite number of steps..
Natural language processing (NLP) is an interdisciplinary subfield of computer science - specifically Artificial Intelligence - and linguistics. It is primarily concerned with providing computers the ability to process data encoded in natural language, typically collected in text corpora, using either rule-based, statistical or neural-based approaches of machine learning and deep learning.
A parse tree or parsing tree or derivation tree or concrete syntax tree is an ordered, rooted tree that represents the syntactic structure of a string according to some context-free grammar. The term parse tree itself is used primarily in computational linguistics; in theoretical syntax, the term syntax tree is more common.
Psycholinguistics or psychology of language is the study of the interrelation between linguistic factors and psychological aspects. The discipline is mainly concerned with the mechanisms by which language is processed and represented in the mind and brain; that is, the psychological and neurobiological factors that enable humans to acquire, use, comprehend, and produce language.
In linguistics, X-bar theory is a model of phrase-structure grammar and a theory of syntactic category formation that was first proposed by Noam Chomsky in 1970 reformulating the ideas of Zellig Harris (1951), and further developed by Ray Jackendoff, along the lines of the theory of generative grammar put forth in the 1950s by Chomsky. It attempts to capture the structure of phrasal categories with a single uniform structure called the X-bar schema, basing itself on the assumption that any phrase in natural language is an XP that is headed by a given syntactic category X. It played a significant role in resolving issues that phrase structure rules had, representative of which is the proliferation of grammatical rules, which is against the thesis of generative grammar.
Parsing, syntax analysis, or syntactic analysis is the process of analyzing a string of symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar. The term parsing comes from Latin pars (orationis), meaning part.
A garden-path sentence is a grammatically correct sentence that starts in such a way that a reader's most likely interpretation will be incorrect; the reader is lured into a parse that turns out to be a dead end or yields a clearly unintended meaning. "Garden path" refers to the saying "to be led down [or up] the garden path", meaning to be deceived, tricked, or seduced. In A Dictionary of Modern English Usage (1926), Fowler describes such sentences as unwittingly laying a "false scent".
In semantics, mathematical logic and related disciplines, the principle of compositionality is the principle that the meaning of a complex expression is determined by the meanings of its constituent expressions and the rules used to combine them. The principle is also called Frege's principle, because Gottlob Frege is widely credited for the first modern formulation of it. However, the principle has never been explicitly stated by Frege, and arguably it was already assumed by George Boole decades before Frege's work.
In linguistics, nominalization or nominalisation is the use of a word that is not a noun as a noun, or as the head of a noun phrase. This change in functional category can occur through morphological transformation, but it does not always. Nominalization can refer, for instance, to the process of producing a noun from another part of speech by adding a derivational affix, but it can also refer to the complex noun that is formed as a result.
Speech segmentation is the process of identifying the boundaries between words, syllables, or phonemes in spoken natural languages. The term applies both to the mental processes used by humans, and to artificial processes of natural language processing.
In generative grammar and related approaches, the logical form (LF) of a linguistic expression is the variant of its syntactic structure which undergoes semantic interpretation. It is distinguished from phonetic form, the structure which corresponds to a sentence's pronunciation. These separate representations are postulated in order to explain the ways in which an expression's meaning can be partially independent of its pronunciation, e.g. scope ambiguities.
Constraint grammar (CG) is a methodological paradigm for natural language processing (NLP). Linguist-written, context-dependent rules are compiled into a grammar that assigns grammatical tags ("readings") to words or other tokens in running text. Typical tags address lemmatisation, inflexion, derivation, syntactic function, dependency, valency, case roles, semantic type etc. Each rule either adds, removes, selects or replaces a tag or a set of grammatical tags in a given sentence context. Context conditions can be linked to any tag or tag set of any word anywhere in the sentence, either locally or globally. Context conditions in the same rule may be linked, i.e. conditioned upon each other, negated, or blocked by interfering words or tags. Typical CGs consist of thousands of rules, that are applied set-wise in progressive steps, covering ever more advanced levels of analysis. Within each level, safe rules are used before heuristic rules, and no rule is allowed to remove the last reading of a given kind, thus providing a high degree of robustness.
Attempto Controlled English (ACE) is a controlled natural language, i.e. a subset of standard English with a restricted syntax and restricted semantics described by a small set of construction and interpretation rules. It has been under development at the University of Zurich since 1995. In 2013, ACE version 6.7 was announced.
The term linguistic performance was used by Noam Chomsky in 1960 to describe "the actual use of language in concrete situations". It is used to describe both the production, sometimes called parole, as well as the comprehension of language. Performance is defined in opposition to "competence"; the latter describes the mental knowledge that a speaker or listener has of language.
Sentence processing takes place whenever a reader or listener processes a language utterance, either in isolation or in the context of a conversation or a text. Many studies of the human language comprehension process have focused on reading of single utterances (sentences) without context. Extensive research has shown that language comprehension is affected by context preceding a given utterance as well as many other factors.
Janet Dean Fodor was distinguished professor emerita of linguistics at the Graduate Center of the City University of New York. Her primary field was psycholinguistics, and her research interests included human sentence processing, prosody, learnability theory and L1 (first-language) acquisition.
The P600 is an event-related potential (ERP) component, or peak in electrical brain activity measured by electroencephalography (EEG). It is a language-relevant ERP component and is thought to be elicited by hearing or reading grammatical errors and other syntactic anomalies. Therefore, it is a common topic of study in neurolinguistic experiments investigating sentence processing in the human brain.
The early left anterior negativity is an event-related potential in electroencephalography (EEG), or component of brain activity that occurs in response to a certain kind of stimulus. It is characterized by a negative-going wave that peaks around 200 milliseconds or less after the onset of a stimulus, and most often occurs in response to linguistic stimuli that violate word-category or phrase structure rules. As such, it is frequently a topic of study in neurolinguistics experiments, specifically in areas such as sentence processing. While it is frequently used in language research, there is no evidence yet that it is necessarily a language-specific phenomenon.
A reduced relative clause is a relative clause that is not marked by an explicit relative pronoun or complementizer such as who, which or that. An example is the clause I saw in the English sentence "This is the man I saw." Unreduced forms of this relative clause would be "This is the man that I saw." or "...whom I saw."
Syntactic parsing is the automatic analysis of syntactic structure of natural language, especially syntactic relations and labelling spans of constituents. It is motivated by the problem of structural ambiguity in natural language: a sentence can be assigned multiple grammatical parses, so some kind of knowledge beyond computational grammar rules is needed to tell which parse is intended. Syntactic parsing is one of the important tasks in computational linguistics and natural language processing, and has been a subject of research since the mid-20th century with the advent of computers.