Just like adults, children derive pleasure and discomfort from different objects, activities and sensations, which leads to the formation of opinions. Parents should take time to identify a child's preferences to encourage interests and foster development in fun and educational ways. However, parents should be careful to let children form opinions -- not merely impart their own -- and promote an open mind toward trying something new.
Give your child options at meals and playtime. For example, serve him two different vegetable sides and encourage him to try both, seeing which he eats first and in its entirety. Offer building blocks and action figures and see which ones he plays with.
Note what your child talks about most passionately and what he asks for when making requests. The topics and items that come up most often are probably favorites. Similarly, pay attention to those items he consistently passes up or refuses to identify what he has little interest in or dislikes.
Play games and read books with your child. See where his imagination takes him, what sort of games and subjects engage him, which leave him bored and what always leaves him wanting more.
Take your child to museums, libraries, bookstores and other educational environments. Let him take the lead and see where he goes. Let your child pick out books on his own. Hands-on children's museums offer fine opportunities to see which subjects engage your kid and which he tires of quickly.
Encourage your child to try new foods and activities so his world is always expanding. Be positive and supportive. Don't push too hard or create negative consequences around exploration; this can leave your child rejecting things and limiting himself without consideration for whether he enjoys them or not. Look at his specific preferences, but also look for common themes. For example, does he take to things that offer puzzles, objects to sort or physical activity?
Notice which games, toys, sports equipment and other items of entertainment your child looks at in stores, gets excited over when a commercial comes on, requests repeatedly. Of course, kids want lots of stuff all the time, so pay attention to whether the interest lasts. Pay attention to the toys that end up gathering dust in his closet, too.
Listen actively to your children. Even when they're very young, despite lacking your extensive vocabulary, they are often quite vocal about what brings them pleasure and what they want nothing to do with. What they talk about and how they talk about it provides endless clues you can use to identify their likes and dislikes.
The subjects children talk about might not always seem important to adults, but they are important to the children. Be glad your child is choosing to share with you, and try to be genuinely interested in what he's telling you. This encourages him to remain open and honest and keeps you apprised of what's going on his life.