Your doctor or psychologist will probably use a test called the DSM-IV to determine if you child has an autism spectrum disorder. The test will consist of the following three categories:

• Social interactions and relationships. For example, a child may have trouble making eye contact. People with autism may have a hard time understanding someone else's feelings, such as pain or sadness.
• Verbal and nonverbal communication. For example, a child may never speak. Or he or she may often repeat a certain phrase over and over.
• Limited interests in activities or play. For example, younger children often focus on parts of toys rather than playing with the whole toy. Older children and adults may be fascinated by certain topics, like trading cards or license plates.

Your child may also have a hearing test and some other tests to make sure that problems are not caused by some other condition. See DSM-IV diagram below. DSM IV CRITERIA FOR AUTISTIC DISORDER
Childhood Disablity ABSTRACT: A. A total of at least six items from (1), (2) and (3), with at least two from (1) and one each from (2) and (3): 1. Qualitative impairment in social interaction as manifested by at least two of the following :

• marked impairment in the use of multiple nonverbal behaviors, such as eye to eye gaze, facial expression, body postures, and gestures to regulate social interaction
• failure to develop peer relationships appropriate to developmental level
• lack of spontaneous seeking to share enjoyment, interests, or achievements with other people (e.g. by a lack of showing, bringing, or pointing out objects of interest)
• lack of social or emotional reciprocity

2. Qualitative impairments in communication as manifested by at least one of the following :

• delay in, or total lack of the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gesture or mime)
• in individuals with adequate speech, marked impairment in the ability to initiate or stereotyped and repetitive use of language or idiosyncratic language
• lack of varied spontaneous make-believe play or social imitative ply, appropriate to developmental level

3. Restricted, repetitive, and stereotyped patterns of behavior, interests and activities, as manifested by at least one of the following:

• encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus
• apparently inflexible adherence to specific, nonfunctional routines or rituals
• stereotyped and repetitive motor mannerisms (e.g. hand or finger flapping or twisting or complex whole body movements)
• persistent preoccupation with parts of objects

B. Delays or abnormal functioning in at least one of the following areas, with onset prior to age three years :

• 1. social interaction
• 2. language as used in social communication or
• 3. symbolic or imaginative play

C. Not better accounted for by Rett disorder or childhood disintegrative disorder. Childhood Autism Rating Scale (CARS) and Autism Behavior Checklist (ABC) are tests widely used for screening and diagnosis of autism in addition to the DSM-IV testing. Please check out the following links: Free Autism Tests How to Administer the Pervasive Developmental Disorders Screening Test