The purpose of this study is to assess the effect of Interactive Guidance Therapy with video feed back (IGT) of parent and child with Autism Spectrum Disorder, under three years of age, using a Single Case Experimental Design (SCED) with multiple baseline across subjects, multicentric, randomized, with multiple replications, blinded scored

The purpose of this study is to assess the effect of Interactive Guidance Therapy with video feed back (IGT) of parent and child with Autism Spectrum Disorder, under three years of age, using a Single Case Experimental Design.

Early Interventions in Autism Spectrum Disorders (ASD) undergo a major development. The investigators identify three generations of early support: 1) Behavioral studies ; 2) Early Intensive Behavioral Interventions (EIBI), inspired by ABA, focused on targeted ASD disorders 3) Naturalistic Behavioral Developmental Behavioral Interventions (NDBI), more ecological, focused on the child's skills.

Among them, methods of video feedback target parental sensitivity (identification, interpretation, response, contingency and synchrony). The VIPP (Video Interactive Positive Parenting) in children less than one year of age, has shown moderate and long term effects on parent-child interaction. The PACT (Preschool Autism Communication Trial) showed immediate and in the long term effects on the synchronization of the parental response, the child initiation, less importantly on the joint attention, and on the autistic symptoms. The dyadic communication allows for changes in autistic symptoms.

Interactive guidance is a brief video-feedback therapy, based on the analysis of "the here and now" with the parent (s), of videotaped interactions with their child. The objective is to strengthen parental skills, their sensitivity, their ability to decipher and respond to the specific needs of their child.

The interest of IGT in the field of ASD, compared to VIPP and PACT, is to offer a standardized feedback intervention adapted to each dyad, according to the child's and parents skills and difficulties, structured on the "here and now" more than on a predetermined sequence of goals.

The investigators use the Single Case Experimental Design (SCED) with multiple baseline across subjects, multicentric, randomized, with multiple replications, blinded scored.

They expect

• to improve the interactive and communicative basic skills of the child, soon after the ASD diagnosis, by accompanying the parents in the identification and understanding of their child's disorders.
• to propose a method highlighting parental skills, in a collaborative and pleasant way
• To increase the parental alliance in the implementation of a tailored intervention for the child
• To facilitate access to healthcare and reduce the parental wandering in the implementation of intervention

Inclusion Criteria:

• 18 months to 3 years child at screening
• Child with a diagnosis of Autism Spectrum Disorder (DSM 5) or pervasive Developmental Disorder (ICD 10)
• Child with ADI R and ADOS-2 fulfilling the criteria for TSA / PDD at diagnosis
• Developmental age > 12 months in motility with the Brunet-Lézine test
• Child with availability of parent most present in daily life, only this parent participating directly in play sessions
• Signed Informed consent form by both parents
• Patient affiliated to the health insurance system

Exclusion Criteria:

• Level of language in French of parents insufficient to benefit from the care and fill in the questionnaires
• Psychiatric parental pathology interfering with interactions with the child, qualitatively assessed by the referring psychiatrist
• Severe sensory illness of the child (blindness, deafness, degenerative disease)