Two professors at the Harvard Medical School testified last week in the trial of John W. Hindley Jr., providing contradictory information about the accused assassin's mental condition when he shot President Reagan and three other victims in an assassination attempt last January.

Dr. Park E. Dietz, assistant professor of Psychiatry, testified that the 27-year-old Hinckley did not have schizophrenia or any other serious mental illness when he shot the president.

Dietz added that Hinckley had suffered from four relatively minor and "quite common" mental disorders, but had never been psychotic or "unable to test reality."

In arguing that Hinckley could discern what was real and what was not real, Dietz contradicted the defense testimony of four medical experts, who had said Hinckley had lost touch with reality and was driven by fantasies to shoot the president.

But Marjorie LeMay, associate professor of Radiology, testified recently that scans of Hinckley's brain suggest strongly that he is schizophrenic. LeMay said the CAT scan of Hinckley's brain showed it to be shrunken to an unusual degree for someone his age. The brain abnormality, she added, is found in only two percent of the normal population, but in about one-third of all schizophrenics.

Dietz and LeMay's testimony followed the testimony three weeks ago of David M Bear, assistant professor of Psychiatry, who said that Hinckley was suffering from schizophrenia. Bear testified for the defense, arguing that Hinckley was not fully responsible for the alleged shooting because his mental disorders had cut him off from reality.