Massa's family doctor, Dino Altman, said Thursday the Brazilian driver was eating and walking around his hospital room.
He also appeared to have no problem in the left eye, which doctors feared had been badly injured in the crash during qualifying Saturday for the Hungarian Grand Prix.
"He is back to normal," Altman said.
Massa, 28, has been recuperating at the AEK hospital in Budapest after undergoing surgery on multiple skull fractures. He was hit in the helmet by a loose part from another car and crashed into a protective tire barrier.
Doctors have ruled out a return to Formula One this season, but Altman said Massa was already sending signals to Schumacher that his comeback might be short-lived.
Ferrari announced Wednesday that the German seven-time F1 champion would come out of retirement to replace Massa until he is fit to return, starting with the European GP on Aug. 21-23, in Valencia, Spain.
"He has no fear at all," Altman told reporters outside the hospital. "He thinks he will be able to race in Valencia."
Altman said no decision had been made about transferring Massa from Budapest. Massa's father said Wednesday he was expecting Massa to be transferred to a hospital in Paris soon.