An electronic device displays a messaging user interface of a message application, including a conversation transcript of a messaging session between a user of the electronic device and a plurality of other users, a message-input area, and a plurality of avatars corresponding to the plurality of other users. The plurality of avatars are displayed as a stack of avatars, with a first avatar of avatars displayed on the top of the stack of avatars. In response to detecting an input by a first contact on the touch-sensitive surface while a focus selector is at a first location in the messaging user interface that corresponds to the first avatar, if the input meets menu-activation-criteria, a menu that contains activatable menu items associated with the first avatar overlaid on the messaging user interface is displayed, and if the input meets avatar-spreading-criteria the plurality of avatars are displayed in an array.