The mothers of children born after World War II and entring the workforce in greater numbers needed surrogate care for their young children. This new form of rearing, discrepant from the tradition of their mothers and grandmothers, evoked uncertainty because of the verity that infants needed the loving care only a bilogical mother could provide.
Jean Piaget's ideas on cognitive development were as second reason for the interest in children. These ideas were not initially popular, either in Europe or in the United States, because Piaget was interested in the growth of logic and reasoning rather than in emotions, morality, and friendships, and he was indifferent to the influcence of caretakers.
Finally, the Soviet launch of a space vehicle, which in the United States provoked a wring of hands over the disheeartening quality of science education in American schools, catalyzed concern with the growth of intellectual talents.
Each of those forces - working mothers, Sputnik, and the writings of Erikson, Bowlby, and Piaget - came together, like the components of a perfect storm, to generate a broadly based curiosity about young children, and private philanthropies and the federal government were ready to provide ample funds for research on children. ibid. 70-71.

The human infant, like billowy summer clouds, invites different perceptions. Montaigne, who saw sixteenth-century infants suckling goats, regarded the life form as an animal. Locke perceived a pristine block of marble ready to be sulpted. Freud's infant was avaricious, while Erikson and Bowlby, wearing rose-colored glasses, portrayed an innocent, gentle, helpless creature looking for care and affection. Each description was an intuition that felt right because of the historical moment in which it was introduced. ibid. 73

The increase in attention to unfamiliar events toward the end of the first year, which is now an established fact, implies a maturational change in brain organization and a parallel change in the ability to relate the representations acquired in the past to the present moment. This ability is called working memory. We now know that one component of the maturation involves the establishment of connections between structures in the temporal lobe and the prefrontal cortex.... The more mature brain enables eight-month-olds to hold in a working memory ciruit the schema of the objects they saw moments earlier.
...
A few years latr Nathan Fox and Sally Weiskopf affirmed this conclusion by repeatedly administering twelve problems requiring working memory to eight infants across the period from five to fourteen months of age. The results were beautiful. The robustness of working memory improved most between seven and ten months in each of the eight infants. The evidence from more than a hundred studies in different labs pints to the same conclusion. Sometime between six and ten months infants begin to "think" for the first time because brain sites that were unconnected in the young brain have become connected. The more mature brain permits the infant to find the representations relevant to a current experience and to keep the tow schemata active until they can be combined. If the cannot, the infant turs away. ibid. p. 77.

Familiar events that are understood immediately, as well as events that bear no relation to the infant's knowledge, even though they are perceptually discriminable, are studied minimally. The longest bouts of attention occur toward events that share elements with the infant's knowledge. ... Put plainly, the interest of infants, like that of adults, is usually recruited by events that differ only a little from what is familiar and therfore are understandable with some effort. It is not a conicidence that thirty years of research on the brain reveals that discrepant and unexpected events are among the most reliable causes of activity in neuronal circuits.
Claude Shannon, the father of information theory, formalized the idea that humans are most likely to be alerted by events that are unexpected. This powerful yet simple principle applies to every aspect of psychological activity. ibid. p. 79.