[ Retroactive visual masking. Use in evaluation and therapeutic trials in senile dementia]

An adaptation of the retroactive visual masking test has been developed, using a micro-computer with automation of the protocol and of the analysis of the results. The essential parameter obtained from this test is the T50 (in ms) which is the delay necessary between the letter and the mask for the subject to be able to correctly identify 50% of the letters which are presented to him. The T50 becomes shorter from childhood until adulthood, then progressively increases. It is significantly longer in elderly hospitalized subjects than in those living at home. The retroactive visual masking test can be used to evaluate the effect of physical training on the intellectual function of elderly subjects. It has good reproducibility with usually negligible learning. It is simple and inexpensive, making it a useful tool in the investigation of intellectual deterioration in the elderly.