Maj. Gen. Lewis B. Hershey, director of Selective Service, said yesterday that defense mobilization officials are studying proposed changes to tighten draft deferments for college students.

The changes, scheduled to become effective in September, provide that high school seniors be allowed to take the Selective Service draft deferment test which only college students have thus far been permitted to take.

In addition, college freshmen in the upper third of their class or who score 70 per cent on the deferment test would be considered for educational exemption. Sophomores will need a grade of 72 per cent, and graduate students will need a score of 80, instead of the present 75.

Hershey emphasized that the local draft boards still have the final say on deferments, but would probably weigh heavily the test scores and class standings.

Other changes will probably follow, Hershey added.