Children with Autism may respond to the same intrinsic rewards a typical child. My children all responded to rewards. At one time one single, solitary skittle was a reward every five minutes to behave in the car. A whole bag lasted for an entire car ride with three children.
Intrinsic rewards are typically rewards that do not have to be paid for. Physical rewards are rewards that are bought or have to be gotten in some way. Both rewards should be paired in preparation for the phasing out. You also need think about how expensive the physical rewards might become over time.
Because some children respond differently than others, sometimes parents also pair two or more intrinsic rewards with success for children with Autism. It really was not my imagination when I noticed that one or another of my children needed bigger rewards. Many professionals have come to agree with this observation as well.
The bigger rewards were in some way true for my daughter with Autism. This might have been because she responded differently, but that is what it took to work.