An electronic device, while displaying a user interface with a favored navigation axis, detects first movement of a contact on a touch-sensitive surface that includes a first component along the favored navigation axis and a second component in a direction different from the favored navigation axis. In response, if first movement meets direction-lock termination criteria, the device moves one or more user interface objects in two dimensions in accordance with both components of the first movement; and if first movement does not meet the direction-lock termination criteria, the device moves user interface objects in one dimension along the favored navigation axis in accordance with the first component of the first movement. After meeting the direction-lock termination criteria, in response to continued second movement of the contact, the device moves user interface objects in accordance with the second movement without regard to whether the second movement meets the direction-lock termination criteria.