Using Radio Buttons
When you tab into a set of enabled radio buttons, you always tab to the currently selected radio button. To move between the radio buttons in the set, use the Up and Down Arrow keys. Note that moving to a different radio button activates that radio button. To leave the radio button set, press Tab (the radio button that has the focus when you leave the set remains selected).
When you tab into a set of disabled radio buttons, you can move between the radio buttons in the set using the Tab key.
For JAWS users: When you tab to a radio button, JAWS announces the radio button’s label and tells you that it is checked. If the radio button is disabled, JAWS announces that it is disabled and tells you whether it is checked or unchecked.