Table 1.

Comparison of cognitive level, IQ, mental age, Piagetian stage, and communication skills in patients with cognitive disabilities

COGNITIVE LEVELIQMENTAL AGE, YPIAGETIAN STAGECOMMUNICATION SKILLS
Borderline70 to 8412 to 16Formal operationsRead and write at a grade 2 to 8 level
Mild55 to 698 to 12Concrete operations to formal operationsRead and write simple phrases, ability to follow simple instructions using prepositions
Moderate43 to 545 to 8Preoperational to concrete operationsMinimal sight vocabulary, understands 2-step commands
SevereHard to test2 to 5PreoperationalTelegraphic speech, understands 1-step commands
ProfoundHard to testInfancy to 2SensorimotorOrients to speech, small vocabulary
  • Adapted from Lougheed.4