Visual evoked potential habituation in mental deficiency.

Habituation of visual evoked potentials (VEPs) may be a helpful tool in the comparative investigation of mental and neural physiologic processes. Through-train and across-train procedures of VEP averaging were performed during habituation in three groups of male children exhibiting mental retardation (idiopathic, exogenous, chromosomal) and in normal children. The children with idiopathic and exogenous mental retardation reached the same VEP habituation level as the normal children (amplitude reduction of 20-60% of early and late VEP components). The across-train averaging showed however a slower than normal development of habituation in these mentally retarded subjects. Habituation failed to occur in the low-grade mentally retarded children, who displayed a reverse tendency of increasing VEP amplitudes and of VEP variability during repetitive flash applications.