Editing Fast mapping (section)

==Cross-situational learning versus propose but verify==
The next question in fast mapping theory is how exactly is the meaning of the novel word learned? An experiment performed in October 2012 by the Department of Psychology by University of Pennsylvania,<ref name=Trueswell>{{cite journal|last1=Trueswell|first1=John C.|last2=Medina|first2=Tamara Nicol|last3=Hafri|first3=Alon|last4=Gleitman|first4=Lila R.|title=Propose but verify: Fast mapping meets cross-situational word learning|journal=Cognitive Psychology|date=February 2013|volume=66|issue=1|pages=126–156|doi=10.1016/j.cogpsych.2012.10.001|pmid=23142693|pmc=3529979}}</ref> researchers attempted to determine if fast mapping occurs via cross-situational learning or by another method, "Propose but verify". In cross-situational learning, listeners hear a novel word and store multiple conjectures of what the word could mean based on its situational context. Then after multiple exposures the listener is able to target the meaning of the word by ruling out conjectures. In propose but verify, the learner makes a single conjecture about the meaning of the word after hearing the word used in context. The learner then carries that conjecture forward to be reevaluated and modified for consistency when the word is used again. The results of the experiment seems to support that propose but verify is the way by which learners fast map new words.<ref name=Trueswell/>

=== Criticisms ===
There is also controversy over whether words learned by fast mapping are retained or forgotten. Previous research has found that generally, children retain a newly learned word for a period of time after learning. In the aforementioned Carey and Bartlett study (1978), children who were taught the word "chromium" were found to keep the new lexical entry in working memory for several days, illustrating a process of gradual lexical alignment known as "extended mapping."<ref>{{cite journal|last1=Swingley|first1=Daniel|title=Fast Mapping and Slow Mapping in Children's Word Learning|journal=Language Learning and Development|date=30 June 2010|volume=6|issue=3|pages=179–183|doi=10.1080/15475441.2010.484412|s2cid=145627474|url=http://www.psych.upenn.edu/~swingley/papers/swingley_LLD10_fastmap.pdf}}</ref>  Another study, performed by Markson and Bloom (1997), showed that children remembered words up to 1 month after the study was conducted. However, more recent studies have shown that words learned by fast mapping tend to be forgotten over time. In a study conducted by Vlach and Sandhofer (2012), memory supports, which had been included in previous studies, were removed. This removal appeared to result in a low retention of words over time. This is a possible explanation for why previous studies showed high retention of words learned by fast mapping.<ref name=Vlach/>{{rp|46}}

Some researchers are concerned that experiments testing for fast mapping are produced in artificial settings. They feel that fast mapping doesn't occur as often in more real life, natural situations. They believe that testing for fast mapping should focus more on the actual understanding of a word instead of just its reproduction. For some, testing to see if the child can use the new word in a different situation constitutes true knowledge of a word, rather than simply identifying the new word.<ref name=Almgren/>