Constant and progressive time delay procedures are techniques used to teach children with autism. The document reviews 22 studies that examine the use of these procedures. It analyzes the demographic characteristics of participants, procedures used, methodologies, and outcomes of the research. None of the previous studies directly compared the effectiveness of constant versus progressive time delay procedures.

1. J Autism Dev Disord (2008) 38:261–275
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
Ó Springer Science+Business Media, LLC 2007
Abstract A review of 22 empirical studies examining the existence, characteristics, symptomatology, and prevalence
use of constant (CTD) and progressive (PTD) time delay of ASD, (b) more refined diagnostic criteria and sub clas-
procedures employed with children with autism frames an sification categories within ASD, (c) empirical evidence
indirect analysis of the demographic, procedural, method- that autism could coexist with other conditions (intellectual
ological, and outcome parameters of existing research. disability, psychiatric disorders, medical conditions), (d)
None of the previous manuscripts compared the two re- development