As we get older, our senses actually "fuse" together, and we lose the ability to focus on isolated pieces of sensory information. This means adults perceive certain events far more accurately than children can... and vice versa.
Once people reach about the age of twelve, they start to combine sensory information to make better sense of the world. This means adults connect, say, related sights and noises into a single unified perception. In other words, while an adult would perceive a big, barking dog as a single entity, a six-year-old would treat the big dog and the frightening barks as two independent sensory events.