Garden-path sentence


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 "wikt:lead someone down the garden path|to be led down the garden path", meaning to be deceived, tricked, or seduced. In A Dictionary of Modern English Usage, Fowler describes such sentences as unwittingly laying a "false scent".
Such a sentence leads the reader toward a seemingly familiar meaning that is actually not the one intended. It is a special type of sentence that creates a momentarily ambiguous interpretation because it contains a word or phrase that can be interpreted in multiple ways, causing the reader to begin to believe that a phrase will mean one thing when in reality it means something else. When read, the sentence seems ungrammatical, makes almost no sense, and often requires rereading so that its meaning may be fully understood after careful parsing.

Examples

"The old man the boat."

This is a common example that has been the subject of psycholinguistic research and has been used to test the capabilities of artificial intelligence efforts. The difficulty in correctly parsing the sentence results from the fact that readers tend to interpret old as an adjective. Reading the, they expect a noun or an adjective to follow, and when they then read old followed by man they assume that the phrase the old man is to be interpreted as determiner – adjective – noun. When readers encounter another the following the supposed noun man, they are forced to re-analyse the sentence. As with other examples, one explanation for the initial misunderstanding by the reader is that a sequence of words or phrases tends to be analysed in terms of a frequent pattern: in this case: determiner – adjective – noun. Rephrased, the sentence could be rewritten as "The old are the persons who man the boat."

"The complex houses married and single soldiers and their families."

This is another commonly cited example. Like the previous sentence, the initial parse is to read the complex houses as a noun phrase, but the complex houses married does not make semantic sense and the complex houses married and single makes no sense at all. The correct parsing is The complex houses married and single soldiers and their families . Rephrased, the sentence could be rewritten as "The complex provides housing for the soldiers, married or single, as well as their families."

"The horse raced past the barn fell."

This frequently used, classic example of a garden-path sentence is attributed to Thomas Bever. The sentence is hard to parse because raced can be interpreted as a finite verb or as a passive participle. The reader initially interprets raced as the main verb in the simple past, but when the reader encounters fell, they are forced to re-analyse the sentence, concluding that raced is being used as a passive participle and horse is the direct object of the subordinate clause. The sentence could be replaced by "The horse that was raced past the barn fell", where that was raced past the barn tells the reader which horse is under discussion. Such examples of initial ambiguity resulting from a "reduced relative with potentially intransitive verb" can be contrasted with the lack of ambiguity for a non-reduced relative or with a reduced relative with an unambiguously transitive verb. As with other examples, one explanation for the initial misunderstanding by the reader is that a sequence of phrases tends to be analysed in terms of the frequent pattern: agent – action – patient. And readers familiar with north England where "fell" is a noun may perceive it as "The horse raced past the fell where the barn is."

Practical impact on language

Garden-path sentences occur in day-to-day use of language. When used intentionally, they appear as a stylistic tool, be it for humorous purposes - e.g. quips like Time flies like an arrow, but fruit flies like a banana, or to convey two distinct meanings by the same sentence in poetry. Unintentional use of garden-path sentences is a common stylistic error, forcing the reader to re-parse the sentence, interrupting the flow and creating unnecessary confusion. These common stylistic errors are usually much simpler than the designed examples, often stemming from the ambiguous expansion of contractions, or applying a subordinate clause to the wrong subject.

Parsing

When reading a sentence, readers will analyse the words and phrases they see and make inferences about the sentence’s grammatical structure and meaning in a process called parsing. Generally, readers will parse the sentence chunks at a time and will try to interpret the meaning of the sentence at each interval. As readers are given more information, they make an assumption of the contents and meaning of the whole sentence. With each new portion of the sentence encountered, they will try to make that part make sense with the sentence structures that they have already interpreted and their assumption about the rest of the sentence. The garden-path sentence effect occurs when the sentence has a phrase or word with an ambiguous meaning that the reader interprets in a certain way and, when they read the whole sentence, there is a difference in what has been read and what was expected. The reader must then read and evaluate the sentence again to understand its meaning. The sentence may be parsed and interpreted in different ways due to the influence of pragmatics, semantics, or other factors describing the extralinguistic context.

Parsing strategies

Various strategies can be used when parsing a sentence, and there is much debate over which parsing strategy humans use. Differences in parsing strategies can be seen from the effects of a reader attempting to parse a part of a sentence that is ambiguous in its syntax or meaning. For this reason, garden-path sentences are often studied as a way to test which strategy humans use. Two debated parsing strategies that humans are thought to use are serial and parallel parsing.
Serial parsing is where the reader makes one interpretation of the ambiguity and continues to parse the sentence in the context of that interpretation. The reader will continue to use the initial interpretation as reference for future parsing until disambiguating information is given.
Parallel parsing is where the reader recognizes and generates multiple interpretations of the sentence and stores them until disambiguating information is given, at which point only the correct interpretation is maintained.

Reanalysis of a garden-path sentence

When ambiguous nouns appear, they can function as both the object of the first item or the subject of the second item. In that case, the former use is preferred. It is also found that the reanalysis of a garden-path sentence gets more and more difficult with the length of the ambiguous phrase.

Recovery strategies

A research paper published by Meseguer, Carreiras and Clifton stated that intensive eye movements are observed when people are recovering from a mild garden-path sentence. They proposed that people use two strategies, both of which are consistent with the selective reanalysis process described by Frazier and Rayner in 1982. According to them, the readers predominantly use two alternative strategies to recover from mild garden-path sentences.
Partial reanalysis occurs when analysis is not complete. Frequently, when people can make even a little bit of sense of the later sentence, they stop analysing further so the former part of the sentence still remains in memory and does not get discarded from it.
Therefore, the original misinterpretation of the sentence remains even after the reanalysis is done; hence participants' final interpretations are often incorrect.

Difficulties in revision

Recent research on garden-path sentences has utilized adult second language learners, or L2 learners, to study difficulties in revision of the initial parsing of garden-path sentences. During the processing of garden-path sentences, the reader has an initial parse of the sentence, but often has to revise their parse because it is incorrect. Unlike adult native speakers, children tend to have difficulty revising their first parsing of the sentence. This difficulty in revision is attributed to the underdeveloped executive functioning of children. Executive functioning skills are utilized when the initial parsing of a sentence needs to be discarded for a revised parsing, and underdeveloped or damaged executive functioning impairs this ability. As the child ages and their executive functioning completes development, they gain the ability to revise the initial incorrect parsing. However, difficulties in revision are not unique to children. Adult L2 learners also exhibit difficulty in revisions, but the difficulties cannot be attributed to underdeveloped executive functioning like in children.
In a 2015 study, adult L2 learners were compared to adult native speakers and native speaking children in revision and processing of garden-path sentences using act-out errors and eye movement. Adult native English speakers, English speaking children, and adult English L2 learners were shown garden-path sentences or disambiguated garden-path sentences that either had reference information or no reference information and then asked to act out the sentence. Adult L2 speakers had fewer act-out errors than native speaking children when the garden-path sentence was presented with referential information, similarly to the adult native speakers that present less act-out errors than both the adult L2 learners and native speaking children. Adult L2 speakers and native adult speakers were able to use discourse and referential information to aid in their processing of the garden-path sentences. This ability could be due to the adults’ developed executive functioning allowing them more cognitive resources, discourse and referential information, to aid in parsing and revision. Additionally, the use of discourse and referential information could be due to L1-transfer because Italian and English share the same sentence structure. However, when the garden-path sentences are disambiguated and then presented, the adult L2 speakers had the highest act-out error rate followed by native speaking children and then by adult native speakers. The results of this study indicate that difficulties in parsing revision are more common than originally thought and are not just confined to children or individuals with reduced executive functioning. Adults, both native speakers and L2 learners, use discourse and referential information in parsing and sentence processing. But adult L2 learners and native speaking children had similar error rates for garden-path sentences with no reference information, indicating systematic revision failure.

Brain processing in computation

One way to determine the brain processes involved is the use of brain electrophysiology. Brain electrophysiology is used to study the impact of disfluencies in sentence processing by the brain, which specifically use event-related potentials. ERPs are voltages generated by the brain that can be measured through a device placed on the scalp. It is also observed that specific components of the ERPs can be associated with the activation of different and specific linguistic processes of the brain.
Within ERPs, P600 is the most important component. Its activation occurs when the parser comes across a syntactic violation such as The broker persuaded to sell the stock or when the parser synthesizes an unsatisfactory disambiguation on an ambiguous string of words such as The doctor charged the patient was lying. Hence, the activation of P600 marks the parser's attempt to revise the sentence's structural mismatch or ambiguity. However, it is also observed that the activation of P600 may be low or completely absent if the parser is asked to only pay attention to the semantic aspects of a sentence either through an explicit instruction or through the use of specific words as a way to force a semantic analysis of the sentence. The result of yet another study conducted by Osterhout in 1997 revealed that the activation of P600 varies with the parser's own attentions to the syntactic violations of the sentence.

Effects of disfluency

sentences have a direct effect on the way sentence structure is built in the parser's mind. Depending on its location within a sentence, a disfluency either aids in the computation of a sentence or forces the parser to linger on the sentence for a longer period of time. It is observed that the more an individual lingers on an incorrect parse, the more it is likely that the sentence will end up being interpreted incorrectly. It also appears that the presence of a disfluency in a sentence—caused by filled and long silent parses—does not elicit the P600. Instead, it elicits another ERP component, N400, which gets activated when people try to integrate a new word into the preceding sentence's context.

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