Some research

Development skills
http://www.literacytrust.org.uk/talktoyourbaby/play.html#playingitup
Child development falls into the two main categories of physical and neurological. Physical skills involve both gross motor skills such as rolling over, crawling and walking, and fine motor skills such as hand-eye coordination, grasping objects, drawing and later writing. Sensory development is also physical and includes sight, sound, touch, smell and taste. Intellectual and cognitive development centre on activity in the brain including use of language, smiling and giggling, imagination and working out. Our children's emotional wellbeing also develops in the brain and comprises many areas such as self awareness, self esteem and the ability to interact with others. Playing in some form or another helps to refine these different areas of development in babies and young children.

toys are simply the best
http://www.literacytrust.org.uk/talktoyourbaby/play.html#simply
Traditional building blocks and Play-Doh are far better for children's learning than high-tech educational toys and videos, experts have revealed. Psychologists are warning that many expensive games might actually restrict children's progress by stifling their creativity and hindering their social skills. American child development expert Professor Kathy Hirsh-Pasek believes youngsters spend too long in front of television and computer screens when they could be playing with basic toys. In a new book titled Einstein Never Used Flash Cards, she claims that so-called 'smart' toys fail to teach children to play imaginatively.