An electronic device displays text of an electronic document on a display; displays an insertion marker at a first position in the text of the electronic document; detects a first horizontal gesture on a touch-sensitive surface; in response to a determination that the first horizontal gesture satisfies a first set of one or more predefined conditions: translates the electronic document on the display in accordance with a direction of the first horizontal gesture, and maintains the insertion marker at the first position in the text; and, in response to a determination that the first horizontal gesture satisfies a second set of one or more predefined conditions, moves the insertion marker by one character in the text from the first position to a second position in the text in accordance with the direction of the first horizontal gesture.