Quantitative behaviour analysis requires the classification of behaviour to produce the basic data. This can be challenging when the theoretical taxonomy does not match observational limitations, or if a theoretical taxonomy is unavailable. Binary keys allow qualitative observation to be used to modify a theoretical taxonomy to produce a practical…

This paper reviews whether Rett syndrome is a subtype of pervasive developmental disorders (PDD). The paper analyzes internal and external diagnostic validity and discusses whether Rett syndrome is a neurological disorder or a mental disorder. The paper concludes that data support the idea of classifying Rett syndrome as a subtype of PDD.…

This paper compared clinicians' diagnosis and DSM-III (Diagnostic and Statistical Manual), DSM-III-R (Revised), and ICD-10 (International Classification of Diseases) diagnoses of 52 individuals with autism and 62 nonautistic, developmentally disordered individuals. The DSM-III-R system overdiagnosed the presence of autism, and ICD-10 closely…

This essay notes the complexities inherent in classifying pervasive developmental disorders (PDD), especially when a single classification scheme is to be used for clinical, research, and administrative purposes. The paper considers principles of classification, symptomatology, the neuropsychiatric interface, the value of a multiaxial approach,…

This study examined the matching and sequencing of quantities, numerals, and arbitrary forms by two individuals with mental retardation. Results showed that sequence training did not readily lead to new matching performances, unlike prior research with college students. Instead, training in matching to sample yielded emergent sequence production…