Doctors emphasize she is in for a long recovery, and her neurosurgeon repeated his cautionary phrase of "she's holding her own."
But there was no denying what was clearly good news.
Giffords, a three-time Democrat, remains in critical condition at Tucson's University Medical Center where she was operated on Saturday after being shot during a meeting with constituents outside a Safeway supermarket. The attack killed six and injured 14 others. Six remained hospitalized.
Special Section: Tragedy in Tucson
Giffords' improvement has been incremental, but impressive. Doctors previously reported she raised two fingers of her left hand and gave a thumbs-up when responding to verbal commands. Now they say she is moving her arms.
"She has a 101 percent chance of surviving," said trauma chief Dr. Peter Rhee said. "She will not die. She does not have that permission from me."
She also can breathe on her own but still has a breathing tube in place as a precaution, said her neurosurgeon Dr. Michael Lemole.
In their briefing Tuesday, doctors also reversed themselves in describing the path of the bullet. They now believe she was shot in the forehead, with the bullet traveling the length of the left side of the brain, exiting the back.
Doctors previously thought she had been shot in the back of the head. They came to the new conclusion after reviewing X-rays and brain scans and consulting with two outside physicians with experience treating combat victims.
The brain's left side controls speech abilities and the movement and sensation of the body's right side. Giffords' doctors will not speculate on the potential for long-term disabilities. But she is lucky the bullet did not cross into both sides, or hemispheres, of the brain, which can do devastating damage.
As doctors continued to monitor Giffords' recovery, details emerged about the care she received when she was rushed by ambulance to the hospital.
Trauma surgeon Dr. Randall Friese was the first to treat Giffords.
"I immediately went over to her bedside and began to coordinate her care," he said.
That meant going through a checklist much like what a pilot would do before taking off. Doctors checked to make sure there weren't any other bullet wounds, put in a breathing tube and assessed her mental state.
Despite not knowing if Giffords could hear him, Friese said he took her hand and told her that she was in the hospital and that doctors would take care of her.
"Then I said, 'Squeeze my hand, Mrs. Giffords.' And she did," recalled Friese.
He asked her several more times to press his hand and she responded.
In the current case, the suspect, 22-year-old Jared Lee Loughner, is being in a Phoenix jail. As more details leak emerge about Loughner's , his family released a statement saying they had their sorrow at the deadly rampage.
On Wednesday, President Obama for a memorial honoring the shooting victims.