An electronic device includes a touch-sensitive surface. The electronic device includes one or more sensors to detect intensity of contacts with the touch-sensitive surface. The device detects a first touch input on the touch-sensitive surface, and, in response to detecting the first touch input on the touch-sensitive surface, determines a first intensity applied by the first touch input on the touch-sensitive surface. The device identifies a first intensity model identifier from a plurality of predefined intensity model identifiers, and, in accordance with the first intensity applied by the first touch input on the touch-sensitive surface and one or more thresholds associated with the first intensity model identifier, determines a first touch characterization parameter. Subsequent to determining the first touch characterization parameter, the device sends first touch information to the first software application. The first touch information includes the first intensity model identifier and the first touch characterization parameter.