Simple Steps to Functional Communication. A key factor of many Developmental Disabilities is a deficit in communication skills. These deficits may include difficulty with expressive language, receptive language, or a combination of both. Expressive language is the ability of an individual to express himself to others while receptive language is the ability to understand what others are communicating. A lack of effective communication can be an endless source of frustration for both individuals with disabilities and those trying to provide support. This lack of effective communication all too often leads to problem behaviors because the individual has no other way to ask for what s/he needs or wants.