The more encounters the child has , the more knowledge she/he gains and the more brain tissue he/she generates. But then, who wants a kid smarter then his/her parents?
The more objects the child can explore, the more opportunity she has to develop the neural infra-structure to process and associate input from more than one modality. This is an early in life
opportunity but someone must be willing to be there to provide the stimuli, the intensity and the safety! Typically, only parents and enlightened extended family are motivated enough to do this.
See the Graphic Version for illustrations of some close encounters of a terrestrial kind.