Devices and methods are disclosed which relate to improving the efficiency of text input by measuring the angle of each key press and rejecting improbable keys pressed at an off-center angle. Examples include a text-entry device which has logic for resisting error while the user enters text on a keyboard of the text-entry device. Each key determines the angle at which the key is pressed. Keyboard logic on the text-entry device assigns a range of acceptable angles to each key. If a key is pressed within the range of acceptable angles, which is typically around the center, then the entry is permitted. If a key is pressed outside the range of acceptable angles, which is typically on the edges, then the entry is denied. Once text is entered, the keyboard logic assigns a prediction value to each key based on a statistical probability that the key will be entered next. The keyboard logic then adjusts the range of acceptable angles based on that statistical probability.