The Wonder Weeks

The Wonder Weeks is the English translation of the Dutch book Oei, ik groei! (literal translation: Ai, i'm growing) by former professor Frans X Plooij, originally published in 1992. The book has sold 200,000 copies world wide. It describes the theory that the cognitive development of babies occurs in predictable jumps. However, a follow-up study by Plooij's PhD student, Carolina de Weerth, failed to find any evidence of predictable leaps. The controversy over these results that ensued led to his resignation as a professor.

According to the book, a baby should go through 10 predictable jumps in its cognitive development during the two years, with 8 in just the first year. These jumps consist of two phases:

1. The baby is generally unhappy, crying a lot, in need of cuddling, and in a bad mood.
2. The baby is generally happy, due to discovering new things with the new cognitive skills.