Linguist Arnold Zwicky has named three linguistic 'illusions' which seem relevant to cognitive bias. They are:
- Frequency Illusion - Once you've noticed a phenomenon, it seems to happen a lot.
- Recency Illusion - The belief that something is a recent phenomenon, when it has actually existed a long time.
- Adolescent Illusion - The belief that adolescents are the cause of undesirable language trends.
Zwicky talks about them here, and in not so many words links them to the standard bias of selective perception.
As an example, here is an exerpt via Jerz's Literacy Weblog (originally via David Crystal), regarding text messages:
- Text messages aren't full of abbreviations - typically less than ten percent of the words use them. [Frequency Illusion]
- These abbreviations aren't a new language - they've been around for decades. [Recency Illusion]
- They aren't just used by kids - adults of all ages and institutions are the leading texters these days. [Adolescent Illusion]
It is my conjecture that these illusions are notable in areas other than linguistics. For example, history is rife with allusions that the younger generation is corrupt, and such speakers are not merely referring to their use of language. Could this be the adolescent illusion in action?
So, are these notable biases to watch out for, or are they merely obvious instances of standard biases?
The distinction drawn here is linguistic descriptivism vs. prescriptivism. If we take "actual linguist" in this context to mean scientific-minded academic researchers, the field largely requires itself by nature to be descriptive--they're attempting to document and describe actual human behavior "in the wild". It is, typically, not the business of scientists to be dictating terms to reality (they leave that to the engineers). As Emily points out, L'Académie française doesn't seem to contain a single academic linguist.
I suspect this is mostly a disagreement on the definition of "linguist".
Some academic linguists further take an active stand against prescriptivism, even outside the context of their field. Language Log has of course discussed the issue, such as some recent posts here and here, which you've probably already read, given that you linked to Language Log in the main post.
Indeed. If someone were to say, "There are no prescriptivist linguists" I'd take that to be a false statement. I've known at least one academic who argued in favor of prescriptivism, and more are out there (thus, the need for academic linguists to argue against prescriptivism).