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. Garden path sentences are used in psycholinguistics to illustrate the fact that when human beings read, they process language one word at a time. "Garden path" refers to the saying "to be led down the garden path", meaning "to be misled".
According to one current psycholinguistic theory, as a person reads a garden path sentence, the reader builds up a structure of meaning one word at a time. At some point, it becomes clear to the reader that the next word or phrase cannot be incorporated into the structure built up thus far; it is inconsistent with the path down which they have been led. Garden path sentences are less common in spoken communication because the prosodic qualities of speech (such as the stress and the tone of voice) often serve to resolve ambiguities in the written text. This phenomenon is discussed at length by Stanley Fish in his book Surprised by Sin. He argues that incremental parsing of sentences needs to be addressed by literary theorists. He also covers this topic in several essays from his book Is there a text in this Class?.
By language type
Garden path sentences mostly appear in analytic languages, where word order is heavily relied upon to establish the grammatical case and function in a sentence. Fusional languages, which establish grammatical function in a sentence through inflection and other types of relational synthesis mostly avoid this type of ambiguity because the relationship of a word to the surrounding words is marked by the way the word is modified.
When reading a sentence, readers will analyze the words and phrases they see and make inferences of 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.
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 means that the reader makes one interpretation of the ambiguity, and continues to parse the sentence in the context of the interpretation. The reader will continue to use their initial interpretation as reference for future parsing until disambiguating information is given.
Parallel parsing means that the reader generates multiple interpretations of the sentence and stores them until disambiguating information is given, at which point only the correct interpretation is maintained.
Re-analysis 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 out that the reanalysis of a garden path sentence gets more and more difficult with the length of the ambiguous phrase.
A research paper published by Meseguer, Carreiras and Clifton (2002) 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.
- The more common one includes the regression of eyes from the first disambiguation directly to the main verb of the sentence. Then the readers reread the remaining of the sentence, fixating their eyes to the next region and the adverb (the beginning of the ambiguous part of the sentence).
- The second and least used strategy includes the regression from the first disambiguation directly to the adverb.
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 analyzing 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 participant’s final interpretations are often incorrect.
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[clarification needed] in sentence processing by the brain, which specifically use event related potentials (ERPs). 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 parses 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 mis-match or ambiguity. However it is also observed that the activation of P600 may be low or completely absent if the parser is asked to pay attention only 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 reveal that the activation of P600 varies with the parser's own attentions to the syntactic violations of the sentence.
The effects of disfluency
Disfluent sentences have a direct effect on the way a 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. There also appears[clarification needed] that the presence of a disfluency in a sentence - caused by filled and long silent parses - does not elicit the P600. Instead they elicit another ERP component, N400, which gets activated when people try to integrate a new word into the preceding sentence's context.
- Branch predictor
- Crash blossom – garden path headlines
- Dangling modifier
- List of linguistic example sentences
- Natural language processing
- Syntactic ambiguity
- Transderivational search
- Dangling else, a similar ambiguous parsing issue with some computer programming languages
- Reisberg, D. (2010). Cognition: Exploring the science of the mind. (4 ed.). New York, NY: W.W. Norton & Company, Inc.
- Hickok, Gregory (1993). "Parallel parsing: Evidence from reactivation in garden-path sentences". Journal of Psycholinguistic Research Journal of Psycholinguistic Research 22 (2): 239–250. doi:10.1007/BF01067832. ISSN 0090-6905. Retrieved 16 November 2012.
- Meng, Michael; Bader, Markus (2000). "Ungrammaticality detection and garden path strength: Evidence for serial parsing". Language and Cognitive Processes 15 (6): 615–666. doi:10.1080/016909600750040580. Retrieved 16 November 2012.
- Ferreria, F., & M Henderson, J. (1991). Recovery from misanalyses of garden-path sentences. Journal of Memory and Language, 30(6), 725-745.
- Meseguer, E., Carreiras, M., & Clifton, C. (2002). Overt reanalysis strategies and eye movements during the reading of mild garden path sentences. Published in partnership with the Psychonomic Society, 30(4), 551-561.
- Patson, N. D., Darowski, E. S., Moon, N., & Ferreria, F. (2009). Lingering misinterpretations in garden-path sentences: Evidence from a paraphrasing task. Journal of Experimental Psychology: Learning, Memory, and Cognition, 35(1), 280-285.
- Osterhout, L., McLaughlin, J., Kim, A., Greenwald, R., & Inoue, K. (2004). Sentences in the brain: Event-related potentials as real-time reflects of sentence comprehension and language learning. In M. Carreiras & C. Clifton, Jr. (Eds.), The on-line study of sentence comprehension: Eyetracking ERP and beyond. Psychology Press.
- Osterhout, L., & Holcomb, P. (1992). Event-related brain potentials elicited by syntactic anomaly. Journal of Memory and Language, 31, 785–804.
- Osterhout, L., Holcomb, P. J., & Swinney, D. A. (1994). Brain potentials elicited by garden-path sentences: Evidence of the application of verb information during parsing. Journal of Experimental Psychology: Learning, Memory and Cognition, 20,786–803.
- Hahne, A., & Friederici, A. D. (2002). Differential task effects on semantic and syntactic processes as revealed by ERPs. Cognitive Brain Research, 13, 339–356.
- Gunter, T. C., Friederici, A. D., & Schriefers, H. (2000). Syntactic gender and semantic expectancy: ERPs reveal early autonomy and late interaction. Journal of Cognitive Neuroscience, 12, 556–568.
- Osterhout, L. (1997). On the brain response to syntactic anomalies: Manipulations of word position and word class reveal individual differences. Brain & Language, 59, 494–522.
- Maxfield, Nathan D.; Justine M. Lyon; Elaine R. Silliman (November 2009). "Disfluencies along the garden path: Brain electrophysiological evidence of disrupted sentence processing". Brain and Language. 111 (2): 86–100.
- Misinterpretations of Garden-Path Sentences: Implications for Models of Sentence Processing and Reanalysis (PDF)
- The Trouble with NLP: Some additional demonstrations of why these and similar examples are hard for computers to deal with when attempting natural language processing.
- Garden path sentences mentioned in Dinosaur Comics.
- Human Sentence Processing: an introductory website on the computational psycholinguistic aspects of human sentence processing, developed for students in Linguistics, Psychology or Computer Science.