The Anti-Rightist Movement was a reaction against the Hundred Flowers Campaign, which had promoted pluralism of expression and criticism of the government. It is not clear whether the Hundred Flowers Campaign was a deliberate tactic to smoke out "rightists", or whether Mao simply decided that it had gone too far.
See http://en.wikipedia.org/wiki/Anti-Rightist_Movement#Origins :
The Anti-Rightist Movement was a reaction against the Hundred Flowers Campaign, which had promoted pluralism of expression and criticism of the government. It is not clear whether the Hundred Flowers Campaign was a deliberate tactic to smoke out "rightists", or whether Mao simply decided that it had gone too far.
My father-in-law spent time in prison with Wang Ruowang, noted dissident mentioned here http://en.wikipedia.org/wiki/Wang_Ruowang