Cross-sectional theory of language acquisition challenged
MedWire News: During the early stages of language acquisition word meanings seem to be gained through the fast mapping of singular conjectures - or "moments of insight" - that are evaluated based on their relevance, experimental findings suggest.
This represents a substantial revision of the current dominant theory that posits a more incremental process based on the probabilistic accumulation of evidence.
Tamara Medina (University of Pennsylvania, Philadelphia, USA) and colleagues conducted three related experiments where they presented study participants with short video vignettes of parents interacting with their children. The sound was muted, except for target words said by the parents (replaced by beep/ nonsense placeholder).
The first experiment was designed to determine how informative the vignettes were in terms of connecting the target word to its meaning.
Of the 288 vignettes, 7% were highly informative (HI) (more than half of the correctly guessed the target word), and the remaining 90% were low informative (LI), demonstrating that even for frequent words, determining the meaning of a word simply from its visual context was difficult.
In the second experiment the researchers mixed the order of HI and LI vignettes.
They found that repeated exposure to the target word did not lead to improved accuracy over time. Moreover, it was only when participants saw an HI vignette first that the accuracy of their final guesses improved; early HI vignettes provided participants with the best opportunity to learn the correct word.
However, when participants saw an LI vignette first they tended to guess incorrectly and, although they revised these guesses throughout the experiment, they were ultimately unable to arrive at the correct meaning.
This inability showed that these participants had no memory of plausible alternative meanings, including the correct one, from earlier vignettes that they could return to.
The third experiment showed that the inability to hold these incorrect meanings in mind is necessary for how word acquisition is likely to work. After a delay of a couple days, participants saw vignettes on the same target word they missed before, but showed no evidence of retaining their incorrect assumptions.
"Learners interrogate scenes and analyze them for a plausible meaning, forming a single conjecture that, unless, explicitly and rapidly countermanded, can last a lifetime," Medina et al conclude in the Proceedings of the National Academy of Sciences of the USA.
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By Andrew Czyzewski