Editing Fast mapping (section)

== Evidence against ==
Today, there is evidence to suggest that children do not learn words through 'fast mapping' but rather learn probabilistic, predictive relationships between objects and sounds that develop over time. Evidence for this comes, for example, from children's struggles to understand color words: although infants can distinguish between basic color categories,<ref name="Bornstein">{{cite journal | last1 = Bornstein | first1 = M. H. | last2 = Kessen | first2 = W. | last3 = Weiskopf | first3 = S. | year = 1976 | title = Color vision and hue categorization in young human infants | journal = Journal of Experimental Psychology | volume = 2 | issue = 1| pages = 115–129 | doi=10.1037/0096-1523.2.1.115| pmid = 1262792 }}</ref> many sighted children use color words in the same way that blind children do up until the fourth year.<ref name="Gleitman">{{cite book|author=Landau, B. |author2=Gleitman, L. R.|year=1985|title=Language and experience: Evidence from the blind child|location=Cambridge, MA|publisher=Harvard University Press}}</ref> Typically, words such as "blue" and "yellow" appear in their vocabularies and they produce them in appropriate places in speech, but their application of individual color terms is haphazard and interchangeable. If shown a blue cup and asked its color, typical three-year-olds seem as likely to answer "red" as "blue." These difficulties persist up until around age four, even after hundreds of explicit training trials.<ref name="Rice">{{cite book|author=Rice, N.|year=1980|title=Cognition to language|location=Baltimore, MD|publisher=University Park Press}}</ref> The inability for children to understand color stems from the cognitive process of whole object constraint. Whole object constraint is the idea that a child will understand that a novel word represents the entirety of that object. Then, if the child is presented with further novel words, they attach inferred meanings to the object. However, color is the last attribute to be considered because it explains the least about the object itself. Children's behavior clearly indicates that they have knowledge of these words, but this knowledge is far from complete; rather it appears to be predictive, as opposed to all-or-none.

=== Alternate theories ===
An alternate theory of deriving the meaning of newly learned words by young children during language acquisition stems from John Locke's "associative proposal theory". Compared to the "intentional proposal theory", associative proposal theory refers to the deduction of meaning by comparing the novel object to environmental stimuli.  A study conducted by Yu & Ballard (2007), introduced cross-situational learning,<ref>{{cite journal|author=Chen, Yu|url=http://www.indiana.edu/~dll/papers/yu_psychscience07.pdf|title=Rapid Word Learning Under Uncertainty via Cross-Situational Statistics|journal=Psychological Science|volume=18|issue=5|year=2006|access-date=18 September 2013|doi=10.1111/j.1467-9280.2007.01915.x|pmid=17576281|pages=414–420|citeseerx=10.1.1.385.7473|s2cid=729528}}</ref> a method based on Locke's theory. Cross-situational learning theory is a mechanism in which the child learns meaning of words over multiple exposures in varying contexts in an attempt to eliminate uncertainty of the word's true meaning on an exposure-by-exposure basis.<ref>{{cite book|author=Frank, Michael|url=http://langcog.stanford.edu/papers/F-chapterunderreview.pdf|title=Learning words through probabilistic inferences about speakers' communicative intentions|access-date=18 September 2013}}</ref>

On the other hand, more recent studies<ref name="Medina">{{cite journal|author=Medina, T. N.|author2=Snedeker, J.|author3=Trueswell, J. C.|author4=Gleitman, L. R.|year=2010|title=How words can and cannot be learned by observation|doi=10.1073/pnas.1105040108|pmid=21576483|pmc=3107260|pages=9014–9019|volume=108|issue=22|journal=PNAS|bibcode=2011PNAS..108.9014M|doi-access=free}}</ref> suggest that some amount of fast mapping does take place, questioning the validity of previous laboratory studies that aim to show that probabilistic learning does occur.  A critique to the theory of fast mapping is how can children connect the meaning of the novel word with the novel word after just one exposure? For example, when showing a child a blue ball and saying the word "blue" how does the child know that the word blue explains the color of the ball, not the size, or shape? If children learn words by fast mapping, then they must use inductive reasoning to understand the meaning associated with the novel word. A popular theory to explain this inductive reasoning is that children apply [[Word learning biases|word-learning constraints]] to the situation where a novel word is introduced. There are speculations as to why this is; Markman and Wachtel (1988) conducted a study that helps explain the possible underlying principles of fast mapping. They claim children adhere to the theories of [[Word learning biases#cite note-Hansen-3|whole-object bias]], the assumption that a novel label refers to the entire object rather than its parts, color, substance or other properties, and mutual exclusivity bias, the assumption that only one label applies to each object.<ref>{{cite journal | last1 = Hansen | first1 = M.B. | last2 = Markman | first2 = E.M. | year = 2009 | title = Children's use of mutual exclusivity to learn labels for parts of objects | journal = Developmental Psychology | volume = 45 | issue = 2| pages = 592–596 | doi=10.1037/a0014838| pmid = 19271842 }}</ref> In their experiment, children were presented with an object that they either were familiar with or was presented with a whole object term. Markman and Watchel concluded that the mere juxtaposition between familiar and novel terms may assist in part term acquisition. In other words, children will put constraints on themselves and assume the novel term refers to the whole object in view rather than to its parts.<ref name=Almgren>{{cite book|author=Braisby, Nick |author2=Dockrell, Julie E. |author3=Best, Rachel M.|year=2001|chapter=Children's acquisition of science terms: does fast mapping work?|editor=Almgren, Margareta |editor2=Barreña, Adoni |editor3=Ezeizabarrena, María-José |editor4=Idiazabal, Itziar |editor5=MacWhinney, Brian |title=Research on child language acquisition: proceedings of the 8th Conference of the International Association for the Study of Child Language|location=Somerville, MA, USA|publisher=Cascadilla Press|pages=1066–1087|chapter-url=http://oro.open.ac.uk/3641/1/IASCL_Paper_II.pdf| archive-url=https://web.archive.org/web/20121207154225/http://oro.open.ac.uk/3641/1/IASCL_Paper_II.pdf | archive-date=2012-12-07 | url-status=dead |isbn=978-1-57473-119-4}}</ref> There have been six lexical constraints proposed (reference, extendibility, object scope, categorical scope, novel name, conventionality) that guide a child's learning of a novel word.<ref name=Almgren/> When learning a new word children apply these constraints. However, this purposed method of constraints is not flawless. If children use these constraints there are many words that children will never learn such as actions, attributes, and parts. Studies have found that both toddlers and adults were more likely to categorize an object by its shape than its size or color.<ref name=Trueswell/>