Puppy's Life Stages
Three to seven weeks: At 3 weeks puppies are given the option to eat some, usually liver or kidneys as this has a very inciting smell to it. Put out two dishes and watch to see which puppy uses its nose to find a dish and eat. This simple test shows who is using their nose and how they use their other senses. Watch to see if they air scent or track the scent closer to the ground. Puppies remember these first impressions, and those who search for their early on tend to continue with this behavior. By the week's end try putting only one dish in for the puppies but hiding it under boxes, towels, or newspapers, so you can continually assess how the puppies tackle each new situation. It is also interesting to separate the puppies and set up a maze in which the puppy has to find it's way to the bowl. The puppy that does this with consistence usually has a great aptitude to use his/her nose and also shows the use of intelligence and problem solving skills. Since stimulation strengthens function of senses it is important to be constantly exposing the puppy to new experiences.
After the fourth week their hearing has developed sufficiently so you can introduce other noises to the puppies: dishwasher, vacuum, power washer, and vibrations from the dryer. For each experience it is best if their mother is available for comfort and to help them with the new experience. Doing so allows the puppies learn to explore new areas but always have a comfort zone to go to. The fourth week is a good time to introduce electronicto the puppies--ones that make whirling noises with bright lights on and off are particularly good. You can also add in that pop up so you can watch how the puppies react to sudden, unexpected changes.