Consistency bias is is the error of overstating the extent to which the past and present are similar, and change bias is overestimating the extent to which the past and present are different. Both of those errors can be found in any political debate, as well as in any unhappy marriage. There would have been no bigoted regime of Hitler without bias. Therefore, we can't remove all stereotypes, but should remove those which are unwarranted by facts. In comprehending bias, imperfect recall of the past is the key to understanding distorted recognition of the present.
Some people continue to be haunted years or decades after unpleasant experiences.
Our survival depended on it when we were hunter-getherers in the forest. People who have frightening memories of being attacked by bears are more likely to be careful to avoid future attacks by bears. Painful or not, evolution favors characteristics which increase the probability that people will survive to reproduce. These seven sins of memory, in this sequence, are the topics of the first seven chapters of the book. 21 pages of notes as an appendix.