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This is a question that is a little bit hard to define for me. I'm interested in learning more about times of "attractor/entrainment" processes that may take place in the body/brain of mammals, and particularly humans. I want to get a general idea of how long it takes for a mammal to switch into a new mode of operation, be it behavior or physiological change? Is it days, weeks or more?

For example, a polar circle animals may change the color of their fur in response to photoperiod changes. How quickly does the change get registered and take place? Is it days, weeks or months?

Another example might be a mating season of siberian hamster, where their testes weight changes in response to photoperiod duration. How long does it take for a behavior change like that to fully manifest?

I've read that it takes ~21 days for a human to create a habit or break one. Is there any biological basis for this observation?

I'm not sure how to search for information like that, as it seems to me such things might only be incidentally mentioned in scientific articles. Are there some keywords that may help me improve the search results?

Thank you for any input.

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closed as too broad by The Last Word, WYSIWYG, Michael Kuhn, Chris, Bez Jun 11 '14 at 9:06

There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs.If this question can be reworded to fit the rules in the help center, please edit the question.

This is still somewhat ambiguous. I think you need to restrict your question to a specific process you are interested in. Learning and switching to a new state can happen on a much shorter time scale (milliseconds to minutes) in the brain. – Memming Oct 12 '12 at 19:04
You can narrow down your question. Just one precise question.. (You are asking 5 questions here ) – WYSIWYG Jun 11 '14 at 5:56