The question as to what type and intensity of stimulation most benefits an infant has been a subject of considerable discussion in the past 50 years, with cycles of "do this" and "don't do that" thrown in by various "experts".  Fortunately for your child, science now has ways to peer inside the brain and see exactly how experiences affect the developing process. 

If you are unsure as to what exact experiences you should be considering, there is a book that puts it all together for you.  Updated in 1999, and entitled Neural Foundations,  it was written by Educational Psychologist Dr. William H. Staso. The book utilizes the professional literature on new findings in brain research to make specific suggestions as to what will assist your infant from birth to 8 months.

Many parents have commented how unique and valuable the ideas are in this book. J.H. from Atlanta wrote that "my husband and I have your first book and it has been the most thorough activity guide we have found for our baby". K.W. from New York stated how she had been using the ideas on a daily basis and was being told by "many people" how very alert, intelligent, and mature her 9 month old daughter was (for other comments see Amazon.com)

Example ideas from the book: 

In the first 5 months, the infant learns about his/her environment almost entirely through vision. Inasmuch as infants are not able to move themselves about to encounter different views, you must consider what it is that you are exposing them to in their surroundings. You can assist them to develop greater sharpness of vision by showing them high contrast (initially black and white and later color) images between 1-4 months of age. If you make these images resemble what will be most important in their lives over the next year or so (such as a 5" black/white image of a spoon), you will assist not only their visual acuity but their developing storehouse of relevant information as well. The infant is actively seeking certain types of data. In general, he/she is trying to appreciate how the immediate environment is organized and what is most common in associations and spatial arrangement. In the process of exposing your baby to the various sights in your home and city, you are affecting the way in which his/her brain is becoming physically structured.

The book spends considerable time offering specific suggestions for visual stimulation by age/development. 

 If  your child is between 8 and 18 months, refer to Dr. Staso's book Brain Under Construction.