The New Knowledge of Dog Behavior by Clarence Pffafenberger outlines how  to grow the puppy’s brain by exposing him to specific stimulus in order to illicit specific neurological responses.  This means the puppy is happy, confident, and curious.

Pffafenberger sited 4 critical periods of development.

• Day 1-19, baby puppies need warmth, food, massage, sleep
• Day 20-49, infant puppies learn to play, learn limits, and learn dominance
• Day 50-84 (7-12 weeks) puppies learn independence and relationships with people and other animals, and they learn fear
• Week 12-16, puppies learn self-confidence, housebreaking, that they must obey, and the difference between play and work

Pffafenberger also outlines methods for growing the senses, which combine  very well into the Rule of 7

• Smell – the breeder’s hair, cinniman, fresh peppers, horseradish, vanilla extract, liver brownies, another dog’s bedding, carrots, bird feathers
• Touch – sheep’s wool, towels, denim, carpet, linoleum, concrete, cold metal pans, newspapers, magazines, indoor-outdoor welcome mat, vinyl, pan of dirt, screen for storm door (do this from Day3+)
• Hearing – movies, radio, talking on phone, other dogs howling, speaker phone, dropping keys and kitchen utensils, bell, cap gun, vacuum, wind-up clock, stomping on floor, slamming doors
• Vibration – Vacuum cleaner, back massager, hair dryer, can opener, mixer
• Sight – people, animals, TV, cars, machines, shrubs, large toys, books, EVERYTHING
• Taste – Beginning Week3, everything