Note 6: 
    P. S. Goldman-Rakic, "Development of Cortical Circuitry and Cognitive Function," Child Development, Vol. 58 (June, 1987) pp. 601-622. 
    Goldman-Rakic concludes that the delayed response test measures the "emergence of representational memory ... the capacity to form representations of the outside world and to base responses on those representations in the absence of the objects they represent."