Modern psychological research has shown that infants begin processing information even before they are born, and impressions made on children have an everlasting effect.   It is for this reason that the Mishna in Pirkei Avot (2:11) heaps praise upon the mother of Rav Yehoshua for bringing him to shul as an infant. The Torah itself commands that little children, and even infants, be brought to Jerusalem on certain special occasions; the atmosphere of holiness experienced by these children would stay with them forever.