Models of Interaction What are They? Guiard’s model of bimanual skill Key-action model (KAM)

Descriptive Models Descriptive models… Descriptive models may be… provide a framework or context for thinking about or describing a problem or situation Descriptive models may be… Simply a verbal or graphic expression of categories or identifiable features in an interface a descriptive model provides the designer with a tool for studying and thinking about the user interaction experience

Detailed Discussion In this presentation, we’ll have a look at just two descriptive models… Guiard’s model of bimanual skill Key-action model (KAM)

Guiard’s Model of Bimanual Skill Humans are not only two-handed, they use their hands differently Studying the between-hand division of labour in everyday tasks reveals that most tasks are asymmetric (I.e., our hands have different roles and perform distinctly different tasks) Guiard’s model… identifies the roles and actions of the non-preferred (non-dominant) and preferred (dominant) hands (next slide)

Guiard’s Model of Bimanual Skill (2) A pretty picture might help (next slide)

Guiard’s Model of Bimanual Skill (3) Non-preferred hand leads the preferred hand sets the spatial frame of reference for the preferred hand performs coarse movements Preferred hand follows the non-preferred hand works within established frame of reference set by the non-preferred hand performs fine movements

Insights Is Guiard’s model of bimanual skill useful? Yes. For one, it suggests that one of the most common interaction tasks in graphical user interfaces is poorly implemented The task is scrolling (next slide)

Scrolling Deconstructed Insight – think about how you do the following: Scrolling should be performed by the non-preferred hand But typically, scrolling is by the preferred hand, namely… By keys (Page Up, Page Down, Home, End, arrows) By the mouse By the wheel in a mouse

Scrolling Using the Non-Preferred Hand Thank you Microsoft (next slide)

Microsoft Office Keyboard

Key-Action Model (KAM) Name of the model Model Keyboard keys can be categorized as… Symbol keys Deliver graphic symbols — typically, letters, numbers, or punctuation symbols — to an application such as an editor Executive / function keys Invoke actions in the application or at the system-level or meta-level. Examples include ENTER, F1, or ESC Modifier keys Do not generate symbols or invoke actions. Rather, they set up a condition necessary to modify the effect of a subsequently pressed key. Examples include SHIFT or ALT. OR

KAM Critique Simple. Has a name. Identifies three categories of keys, providing for each a name, a definition, and examples. What do you think of this model? Is it correct? Is it flawed? Do all keyboard keys fit the model? Can you think of additional categories or sub-categories to improve the model or to make it more accurate or more comprehensive? Do some keys have features of more than one category? Can you think of a graphical illustration of the model to improve its expressive power? Is the model useful? Let’s see (Next slide)

KAM Implementation Here it is… Is this useful? Hmm… there appears to be a right-side bias of executive and modifier keys, or “power keys” In fact, this is great for left-handed users (next slide) Unique power keys

The Left-Handed GUI The desktop interface is biased for left-handed users!

Redesigning the Right-Handed GUI Right-handed users manipulate the mouse with their right (preferred) hand There is a need to empower the left hand; e.g., scrolling and access to power keys The solution? (next slide)

Microsoft Office Keyboard

References MacKenzie, I. S. (in press). Motor behaviour models for human-computer interaction. In J. M. Carroll (Ed.) Toward a multidisciplinary science of human-computer interaction. San Francisco: Morgan Kaufmann. MacKenzie, I. S., & Guiard, Y. (2001). The two-handed desktop interface: Are we there yet? Extended Abstracts of the ACM Conference on Human Factors in Computing Systems – CHI 2001, pp. 351-352. New York: ACM.