Figure 12.2: Evidence of infant monkeys’ preference for the cloth surrogate These graphs show (a) the average number of hours that Harlow’s monkeys spent on each of the surrogate mothers and (b) the percentage of time that they ran to each when they were frightened by a strange object. Notice that the preference for the cloth surrogate was as strong for the monkeys that were fed on the wire surrogate as for those fed on the cloth surrogate.

(Based on data from Harlow, 1959.)