This is not an overstatement. Intellectual skills are more resilient and can be compensated for, there is more plasticity, emotional development is very difficult. An infant can recover from a deprived intellectual environment much easier than she can recover from emotional abandonment or neglect. We say how entrenched this damage can be in looking at attachment disorder. It is the budding parent-child relationship we must protect.
Unrealized genius is a cliche in our society, brilliant psychopaths, depressed prodigies.
When we speak of critical windows of neural development and infant stimulation we must keep in perspective this need for emotional grounding. No, we are basically talking about attachment, or the unscientific word, love. We worry about what children three and even younger should know and be able to do, and want programs to measure it. Experiencing the everyday world on the arm of a loving parent is all the special stimulation and material that most babies need. The secure attachment of the infant to the mother is the critically important element for the child's overall development.