The concept of Cause and Effect is basic to the use of language.
Mirrors: Having mirrors available for young infants (and older) to see themselves is also a excellent practice. Visual feedback is helpful for the development of any motor skill, but when the child finally recognizes themselves in the mirror, they have attained a special level of awareness reached by few living creatures--recognition of self! This is a wonderful phenomenon for a partent to observe.
2. Cause and Effect: Much of what language is, is a description of cause and effect. The structure of English reflects this. Someone (the noun phrase) has caused something to happen to someone else (the verb phrase--kernel sentence type II). Hence, the understanding of cause and effect is critical to language use and understanding.