The concept of sensitive periods

I’ve been reading a fascinating article Sensory, Emotional, and Social Development of the Young Dog. It says that it is as though the puppy were in a train with all the windows closed. At certain points a window opens and the information outside is available. If the puppy accesses that information they acquire that particular social, emotional or behavioural development. That window then closes and another opens, and it becomes much more difficult for the puppy to access the information that was outside the first window.

This notion of learning in phases has various names: sensitive period, critical moment, optimal stage and so on. Dehasse uses ‘sensitive period’ saying that this is a point in the maturing process when events are likely to have long term effects, or a period when learning is easier and knowledge gained is stored in the long term-memory. During the sensitive period, small experiences can have major effects on future behaviour.