(1) The student may be identified as having cognitive delay if the student has a significantly subaverage general intellectual functioning and corresponding deficits in adaptive behavior and educational performance, especially in the area of application of basic academic skills in daily life activities.
(2) "General intellectual functioning" means performance on a standardized intelligence test that measures general cognitive ability rather than one limited facet of ability.
(a) "Significantly subaverage general intellectual functioning" is defined as two or more standard deviations below the population mean on a standardized intelligence test. Error in test measurement requires clinical judgment for students who score near two standard deviations below the mean.
(b) The presence of subaverage general intellectual functioning must occur during the developmental period defined as the period of time between conception and the 18th birthday.
(3) Deficits in adaptive behavior is defined as significant limitations in the student's effectiveness in meeting the standards of personal independence, interpersonal communication, and social responsibility expected for the student's age/grade peers and cultural group as measured by standardized instruments or professionally recognized scales.