The field of Applied Behavior Analysis (ABA) is continually evolving in order to provide treatment for a range of unique abilities and needs. This has resulted in the creation of new modalities and tools for treatment, including toys. Research has proven that children progress in ABA therapy through the use of play therapy, a natural part of early childhood development, so specific toys have been developed to aid in ABA therapy.
Toys can be helpful for many different reasons, such as the development of play skills, coordination, fine and gross motor skills, teaching appropriate behaviors, and many more. Play skills are extremely important, not just from a social perspective, but also from a developmental perspective. Establishing strong play skills from an early age can also help to establish a foundation for cognitive, physical, and speech and language skills, so incorporating appropriate toys into ABA therapy can be incredibly beneficial. As children grow during ABA therapy, the toys can also be adapted to meet their ability and age level.
Here is a list of toys commonly used in ABA therapy:
Sensory toys: Many children with autism experience difficulties concentrating during school (or other structured activities) and can benefit from sensory toys. The goal of these toys, such as fidgets and rollers, is to help children focus by keeping their hands busy.
Puzzles: Puzzles can be a helpful method for teaching problem solving skills in ABA therapy, and they can also be tailored for a wide range of ability and age levels.
Games: There is a wide range of games, from blocks to board games, which can be used during ABA therapy to work on cognition and communication skills. Some games are also tailored to help children who have a sensory processing disorder.
High-interest area toys: Children who are on the autism spectrum frequently have an area of high interest, such as Thomas the Tank Engine or dinosaurs. Therapists can incorporate these areas of interest into the toys used in ABA, in order to keep the child engaged and actively participating. Children may also be more expressive if playing with a toy that is their high-interest area.
Early intervention toys: Basic instruments and train sets, for example, can help children learn a variety of skills in early ABA therapy. Some of these skills include communication, learning cause and effect, and motor skills. 
