How to Evaluate Multi-Touch While Standing in a Store

Multi-touch interfaces are becoming increasingly popular for handheld devices and portable electronics. There are a number of technologies that can be used to implement multi-touch functionality. Are they all the same? What are the properties that distinguish a good multi-touch technology from a great one, and how can you test for these properties? This paper describes simple techniques for testing a multi-touch interface, which don't require any special tools or software. The paper relies on simple test utilities which are usually available for any given system.