In both 1960 and 1980, the same test of spatial-visual ability was given to national probability samples of high school seniors in the United States. The students in 1960 were participants in Project TALENT and in 1980 were participants in "High School and Beyond." In addition, a reading comprehension test was given to the 1960 students that subsequently was equated to a similar reading test given to the 1980 seniors. In 1960 the males had substantially higher scores in visualization and slightly higher scores in reading. Between 1960 and 1980 all means scores declined but substantially more so in visualization. However, the gap between males and females narrowed, particularly in visualization. In the absence of a clear explanation, the report attributes the general decline primarily to less student attrition in 1980 and the differential decline to convergence in the experiences of males and females. (Author)