People rely on implicit interaction in their everyday interactions with one another to exchange queries, offers, responses, and feedback without explicit communication. A look with the eyes, a wave of the hand, the lift of the door handle--small moves can do a lot to enable joint action with elegance and economy. This work puts forward a theory that these implicit patterns of interaction with one another drive our expectations of how we should interact with devices. I introduce the Implicit Interaction Framework as a tool to map out interaction trajectories, and we use these trajectories to better understand the interactions transpiring around us. By analyzing everyday implicit interactions for patterns and tactics, designers of interactive devices can better understand how to design interactions that work or to remedy interactions that fail. This book looks at the "smart, " "automatic, " and "interactive" devices that increasingly permeate our everyday lives--doors, switches, whiteboards--and provides a close reading of how we interact with them. These vignettes add to the growing body of research targeted at teasing out the factors at play in our interactions. I take a look at current research, which indicates that our reactions to interactions are social, even if the entities we are interacting with are not human. These research insights are applied to allow us to refine and improve interactive devices so that they work better in the context of our day-to-day lives. Finally this book looks to the future, and outlines considerations that need to be taken into account in prototyping and validating devices that employ implicit interaction.

1. Introduction -- 1.1 Background -- 1.2 The theory of implicit interactions -- 1.2.1 Point of view -- 1.3 Book overview -- 2. The theory and framework for implicit interaction -- 2.1 Actors in the framework -- 2.2 Implicit interaction framework -- 2.2.1 Attentional demand -- 2.2.2 Initiative -- 2.3 Interaction paradigms -- 2.3.1 Foreground reactive -- 2.3.2 Foreground proactive -- 2.4 Interaction trajectories -- 2.5 Interaction analogues -- 2.6 Interaction pitfalls -- 2.7 Conclusion -- 3. Opening the door to interaction -- 3.1 Identifying implicit interactions -- 3.2 Analyzing implicit interactions -- 3.3 Designing implicit interactions -- 3.4 Implicit interaction patterns -- 3.5 Verifying/validating patterns -- 3.6 Wizard-of-Oz techniques -- 3.7 Video prototyping techniques -- 3.8 Findings -- 3.9 Conclusion -- 4. Light and dark: patterns in interaction -- 4.1 The difference between pattern diagrams vs. state diagrams -- 4.2 Command-based interaction -- 4.2.1 Breakdowns invoke the interactive paradigm -- 4.2.2 Common errors: misperception, misjudgment, misexecution -- 4.2.3 Repairs -- 4.2.4 Basic patterns -- 4.3 Interactions with "automatic switches" -- 4.3.1 Automatic systems hide problems -- 4.3.2 Using feedforward to show future actions -- 4.3.3 Testing background proactive systems -- 4.4 Interactive switches -- 4.4.1 Interaction errors -- 4.4.2 Repairs and overrides -- 4.4.3 Guiding lights -- 4.5 Dark patterns -- 4.6 Invisibility is a consequence and not a cause of good design -- 4.7 Conclusion -- 5. Action and reaction: the interaction design factory -- 5.1 Proxemics, or, dancing with the materials of design -- 5.1.1 The role of proxemics in interaction -- 5.1.2 Proxemics in interaction design -- 5.2 Intention -- 5.2.1 The dark pattern of secret robotic plotting -- 5.2.2 The role of intention in interaction -- 5.2.3 Intention in interaction design -- 5.3 Consistency -- 5.3.1 The head-in-a-head problem -- 5.3.2 The role of consistency in interaction -- 5.3.3 Consistency in interaction design -- 5.4 Conclusion -- 6. Driving into the future, together -- 6.1 The rationale for automation -- 6.2 Interaction design on the critical path -- 6.3 The right analogue is key -- 6.4 Transfer of control -- 6.5 Watch out for people -- 6.6 Know when to ignore the rules -- Bibliography -- Author biography.