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J Autism Dev Disord (2008) 38:261275 DOI 10.1007/s10803-007-0390-4
ORIGINAL PAPER
Constant and Progressive Time Delay Procedures for Teaching Children with Autism: A Literature Review
Gabriela Walker
Published online: 2 June 2007 Springer Science+Business Media, LLC 2007
Abstract A review of 22 empirical studies examining the use of constant (CTD) and progressive (PTD) time delay procedures employed with children with autism frames an indirect analysis of the demographic, procedural, methodological, and outcome parameters of existing research. None of the previous manuscripts compared the two response prompting procedures. This review suggests that the effectiveness of the two procedures is similar on some variables. However, the CTD procedure resulted in more errors to criterion, a greater magnitude of procedural modications, and in a delayed moment of transfer of stimulus control than in the PTD studies. Conclusions may inuence clinical and educational practices and indicate a need for research.
Keywords Constant time delay Progressive time delay Time delay Autism Autistic-like Review
Introduction
After the rst clinical description of the syndrome (Kanner, 1943) and prior to 1990, relatively few individuals were identied with Autism Spectrum Disorders (ASD). Since then a higher percentage of children have been correctly diagnosed with ASD. Possible reasons for an increased prevalence include (a) increased public awareness of the
existence, characteristics, symptomatology, and prevalence of ASD, (b) more rened diagnostic criteria and sub classication categories within ASD, (c) empirical evidence that autism could coexist with other conditions (intellectual disability, psychiatric disorders, medical conditions), (d) development of specialized services, (e) increased advocacy, (f) increased funds allocated to ASD research have led to increased research on teaching interventions for individuals with autism, and (g) a possible true increase in the number of individuals displaying autistic symptoms (Bristol et al., 1996; Kabot, Masi, & Segal, 2003; Wing & Potter, 2002).
ASD, also known as pervasive developmental disorders (PDD), are neuro-developmental disorders characterized by a triad of symptoms: (a) impaired reciprocal social interaction, (b) impaired verbal and nonverbal communication, and (c) stereotyped behaviors restricted to certain interests (DSM IV-TR, American Psychiatric Association, 2000; ICD-10, 1993). These symptoms are both quantitative and qualitative in nature, i.e., some symptoms may be manifested in a delayed fashion and others in a deviant fashion. Autistic-specic characteristics are not limited, however, to these three core...