A TEST OF CONDITIONED BLOCKING AND ITS DEVELOPMENT IN CHILDHOOD AND ADOLESCENCE - RELATIONSHIP TO PERSONALITY AND MONOAMINE METABOLISM

Conditioned blocking (CB) is the undermining of conditioning to a stim ulus by conjoint exposure with one already associated with the uncondi tioned stimulus. CB is one of several tests of ''learned inattention'' in which performance has been found to depend on personality features of human participants and monoamine activity in animals. In Part 1, t he performance of 25 healthy young adults on a new test form for demon strating CB is described. From personality inventories and 24-hr urine samples it was proposed that CB may be correlated with extroversion a nd increased catecholamine utilization. In Part 2, CB was shown to be present in 4 groups of 11 participants with mean ages of 10, 14, 17 an d 22 years independent of IQ, but it was least marked in the prepubert al group. No relation of performance with personality features was fou nd. As with the adult group, CB was positively correlated with dopamin e activity, but unlike the adults it was negatively correlated with no radrenalin activity. The maturation of attention-related information p rocessing is discussed in terms of the development of limbic structure s and dopaminergic versus noradrenergic function.