People perceive patterns in representations, patterns that may not have been initially intended. This phenomenon of emergence is deemed to play an important role in design. Computer based design assistants can and should support this human perceptual ability, using pattern recognition to anticipate human designers’ perception of emergent shapes and supporting the subsequent manipulation of and reasoning with these shapes as part of the design. Freehand drawing programs with gesture recognition are well positioned to implement shape emergence. Support for emergent shapes in the Back of an Envelope system is described.

Back of an Envelope