“…These authors did note that participants had limited verbal communication abilities, and there were no formal assessments of participants’ skill levels before the comparison was conducted. Researchers then began to investigate the role of hypothesized prerequisite skills such as IQ (e.g., Cohen‐Almeida, Graff, & Ahearn, ; Wilder, Ellsworth, White, & Schock, ), matching abilities (e.g., Clevenger & Graff, ; Cohen‐Almeida et al, ; Graff & Gibson, ), verbal repertoires (e.g., Higbee, Carr, & Harrison, ; Kuhn, DeLeon, Terlonge, & Goysovich, ), and discrimination abilities (e.g., Conyers et al, ; de Vries et al, ). Overall, multiple prerequisite skills have been assessed across numerous investigations; however, it is difficult to draw conclusions on which skills are pertinent because they have not been assessed systematically.…”