Ed Zigler's developmental approach to intellectual disabilities: Past, present, and future contributions

Abstract

Comprising two parts, Ed Zigler's developmental approach has greatly influenced how one conceptualizes children with intellectual disabilities (ID). In part one, Zigler championed a “two-group approach” concerning the cause of children's ID. He distinguished persons with a clear, organic cause of their ID from those displaying no clear cause. Members of this “organic” group often displayed IQs below 50 and co-occurring physical–medical conditions. The second, “cultural–familial” group, mostly showed IQs of 50–70, did not possess co-occurring physical or health problems, and often came from families of lower IQs and lower socioeconomic status. While the presence of these two groups has been supported, recent advances have also further differentiated the organic group, mostly in relation to behavioral phenotypes of persons with several genetic etiologies. In part two, Zigler championed the child with ID as a “whole person.” Originally focused on the child's reactions to social deprivation and failure, recent studies directly examine parent–child, within-family, and wider system interactions throughout the life span. For decades a force within the ID field, Zigler's developmental approach to children with ID continues to influence researchers, interventionists, and policymakers.

Words Don’t Come Easy : Decoding and Reading Comprehension Difficulties in Adolescents with Intellectual Disability

“…Furthermore, Zigler (1967) stressed that the performance level of individuals with ID could not be attributed solely to cognitive functioning. Instead, he argued for a holistic approach ("whole child") and placed a focus on social-personality characteristics that had been largely absent in the existing literature on ID (Hodapp, 2021). This line of reasoning fits well with the aforementioned biopsychosocial model that was proposed a decade later (Engel, 1977).…”

Profiles and trajectories of executive functioning in young children with Down syndrome

“…contributions to science have continued to shape the way that researchers and clinicians think about individuals with intellectual disability (ID). Of note, Ed Zigler was a champion of the universal developmental approach, which espouses the belief that development is a universally human experience, regardless of ID status (Burack et al 2021;Hodapp 2021). His approach emphasised that individuals with ID follow similar developmental trajectories as do their typical developing (TD) peers, albeit at a slower pace.…”

Intellectual functioning in survivors of extremely low birthweight: Cognitive outcomes in childhood and adolescence

“…Beginning with Ed Zigler's (1967Zigler's ( , 1969 seminal writings, developmental researchers have recast theory and policy regarding persons with intellectual disability (ID) (for reviews, see Hodapp 2021;Burack et al 2021b). Zigler's approach was fundamentally rooted in compassion emanating from his own experience of poverty and marginalisation, in behaviourist methodology that offered reliable evidence to improve the lives of children with ID and in his unwavering determination to undermine the intellectual errors and prejudices that compound the daily difficulties faced by these children and their families (Burack et al 2021a).…”

“…Initially, Zigler (1967Zigler ( , 1969 did not extend this continuum to persons whose ID he labelled as organic, who had clear indication of physiological or genetic aetiology, neurological differences or accidental brain damage. He proposed a second distribution curve for IQ to account for individuals with these organic sources of disability that was superimposed on the curve for the general population, but lower down on the distribution of IQ (Zigler 1967; see also Hodapp 2021).…”

“…Subsequently, other developmental researchers, most notably Dante Cicchetti and colleagues (Cicchetti & Pogge-Hesse 1982;Cicchetti & Ganiban 1990), expanded the scope of developmental theorising to include children with organic sources of disability, with considerable discussion of the extent to which their development patterns resemble those of neurotypical children with milder or familial forms of ID (Burack et al 2016;Hodapp 2021;Burack et al 2021b). Although developmental profiles differ considerably across specific aetiological groups (e.g.…”