parents not to play with their babies. John B. Watson's 1924 Behaviorism argued that parents could train malleable children by rewarding good behavior and punishing bad, and by following precise schedules for food, sleep, and other bodily functions. Although such principles began to be rejected as early as the 1930s, they were firmly renounced in the 1946 best-seller Baby and Child Care, by pediatrician Benjamin Spock, which told parents to trust their own instincts and to view the child as a reasonable, friendly human being. Dr. Spock revised his first edition to urge more parent-centered discipline in 1957, but critics blamed his popular book for its permissive attitude during the youth rebellions of the 1960s and 1970s. In the last half of the century, Parent Management Training was developed and found to be effective in reducing child disruptive behavior in randomized controlled trials. Conservative backlash Following the permissive trend of the 1960s and early 1970s, American evangelical Christian James Dobson sought the return of a more conservative society and advocated spanking of children up to age eight. Dobson's position is controversial. As early as 1985, The New York Times stated that "most child-care experts today disapprove of physical punishment." Corporal punishment In many cultures, parents have historically had the right to spank their children. A 2006 retrospective study in New Zealand, showed that physical punishment of children remained quite common in the 1970s and 1980s, with 80% of the sample reporting some kind of corporal punishment from parents, at some time during childhood. Among this sample, 29% reported being hit with an empty hand. However 45% were hit with an object, and 6% were subjected to serious physical abuse. The study noted that abusive physical punishment tended to be given by fathers and often involved striking the child's head or torso instead of the buttocks or limbs. Attitudes have changed in recent years, and legislation in some countries, particularly in continental Europe, reflect an increased skepticism toward corporal punishment. As of December 2017, domestic corporal punishment has been outlawed in 56 countries around the world, most of them in Europe and Latin America, beginning with Sweden in 1966. Official figures show that just 10 percent of Swedish children had been spanked or otherwise struck by their parents by 2010, compared to more than 90 percent in the 1960s. The Swedish law does not actually lay down any legal punishment for