Autism is a tripod. In order to be diagnosed, a child needs to fit at least two of three criteria: delayed or lack of communication, absence or lack of social interaction, and to practice certain behaviors (most of which can fall under the sensory intergration disorder umbrella, or just be plain self-stimulation behavior - head-banging, rocking, inappropriate hand movements and the like).
Among these three main criteria are a bunch of sub-categories. One of these is imaginative play. Most children with autism do not or rarely engage in pretend play. Either because they don't know how, or they just can't conceive of doing something imaginary when the real world is already such a challenge for them to deal with on a daily basis.
If you give a child with autism a toy truck, he or she may put it in his/her mouth, spin its wheels, or roll the toy along but without a "destination" in mind - just rolling for the sake of it. They need to be taught what comes naturally to other children - that pretending is not silly or pointless, but healthy and fun.
Little A's pretend play came along gradually. He loves animals, so apart from lining them up and spelling their names, we put them on habitat boards, or take them into their "environments" - sea creatures in the bathtub, zoo animals in the plants. He enjoys the wonderful dollhouse in the dental office next to the therapy centre, but still needs more encouragement and time to create play scenarios for Madeline and her friends.
Seeing him pretending to ride a plastic giraffe at school, trot and jump a toy horse over fences and feed a little dog without prompting are causes for much joy in our house.
If there's anything you learn from living with autism, it's that steps can be infinitesimally tiny, but when they are made, a huge leap is achieved in the child's brain. These miniscule gains are massive to the likes of us, and the promise of these and the hope that more will come are what keep us going, moment after moment, day after day.