Iterated learning model
One alternative to Chomsky’s theory of language learning.
Definition
What is iterated learning?
Iterated learning is the process by which one individual’s competence is acquired on the basis of observations of another individual’s behavior, which is determined by that individual’s competence. This model of cultural transmission has proved particularly useful in studying the evolution of language.1
Another definition:
The process by which a behaviour arises in one individual through induction on the basis of observations of behaviour in another individual who acquired that behaviour in the same way.2
Differences from Chomsky’s theory
According to Chomsky, humans can learn their native language with only minimal linguistic input because they are born with a language acquisition device. The device is needed because the linguistic input is insufficient (the poverty of the stimulus argument).
The iterated learning model also accepts that linguistic input is insufficient. But rather than arguing that humans therefore need a language acquisition device, it argues that language itself has changed into a form that is easy to learn.
According to this model, language is transmitted culturally through the following mechanism:
- Agents in the previous generation who possess linguistic competence produce linguistic input.
- Agents in the next generation who lack linguistic competence acquire it from that input.
- Agents who have acquired linguistic competence produce linguistic input through linguistic behavior.
- Repeat.
Because linguistic input is insufficient (poverty of the stimulus), language culturally adapts to take a particular form. The resulting form is its compositionality.
Notes
This brings to mind Mark Changizi’s Harnessed (2011) and The vision revolution (2009).
Humans have not biologically adapted to reading and writing. Nor do we put in an enormous amount of effort to read and write. If it is neither evolutionary adaptation nor enormous amounts of acquired learning, then what? These two books offer a third explanation: writing has evolved (culturally). The shapes of written characters gradually changed into forms our brains can easily accommodate, allowing humans to read them incredibly quickly with almost no biological evolution or acquired learning specifically for writing.
From this perspective, the iterated learning model can be explained as follows. A shortage of linguistic input does not necessarily require something biologically innate that is specialized for language acquisition, because language’s structure itself can change into a form that is easy to acquire even with limited input.
This only argues that a language acquisition device is not strictly necessary, not that it must not exist. Thinking we must choose one of the two positions may be a false dichotomy. Reality is probably a combination of:
- A small number of evolutionary adaptations specialized for human language alone
- Repurposing preexisting biological adaptations
- Changes in language itself (in directions that make good use of the two above)