Dr. Michael Lemole said her eyes are opening more frequently and she can carry out more complex sequences of activity in response to commands and on her own.
Giffords was shot in the head Saturday in an attack in Tucson that wounded 12 others and killed six people.
She remained in critical condition and still a the breathing tube in. Trauma surgeon Dr. Peter Rhee said it could be removed within a day.
Giffords’ husband, astronaut Mark Kelly, posted a message on Twitter Friday thanking people for the messages of support and said “GG,” as he referred to her, was “improving each day.”