Based on the results of the two studies and the discussions of their implications, I propose four points of interest for interface designers choosing where to locate their tool containers.
6.3.1 It’s not just Fitts’s Law
The first, and likely the most important, point is that the selection time (the measure provided by Fitts‟s Law) is not the only user performance measure affected by tool container location. I have shown in this thesis that other factors of user performance are also affected by tool container location choice, specifically, attention and group awareness. In addition to these user performance factors, I have also described many issues that can arise from tool container properties in the three locations of the taxonomy.
For example, although all tool containers inherently require some screen real-estate, the different tool container locations occlude different parts of the workspace. Fitts‟s Law states the in-place
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tool containers afford faster tool selections than tool containers displayed farther away from the point of interaction; however, in-place tool containers occlude the area of the workspace around the point of interaction, which can cause users to forget which tool they wanted to select (this was observed with Shadow Cursor, in study 1). Hence, although in-place tool containers afford faster selections, there are additional issues introduced by occluding the workspace around the point of interaction.
Another example is that the location of a tool container can inform a user about which item in the workspace it will affect (Section 3.2.4). An in-place tool container provides the most obvious link between the tool and the workspace item, whereas an inside workspace tool container provides at least an application and/or workspace link. Tool containers in the outside workspace location do not necessarily have these intrinsic links, so interface designers should include artificial cues, such as labels or link lines, to inform the user of this link.
6.3.2 Location, location, location
In all direct touch applications, there is occlusion of the tool container by the interaction device (the finger or stylus). This is particularly cumbersome for users on tabletop displays when the tool containers are static, such as the personal location in study 2. In this situation, players often observed that their arm occluded their toolbars, because they had to reach over their toolbars in order to hover in their bonus box (which is to say, interacting in their personal workspace). This observation is important, because it suggests that for direct input, a toolbar along the edge of the table should not be centered in front of the user. Had the toolbar been offset slightly, players would not have occluded their toolbars with their arms. Another problem players described was that the shadow of their arm occluded their toolbars when they were making selections. This is a problem with all direct touch tool containers.
6.3.3 Outside of workspace may be a good location for tool containers
There are few tool containers that are displayed outside of the user‟s workspace; however, these tool containers may offer benefits to the users that may not be easily achieved by tool containers
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displayed at the other locations. This has been shown to be the case for tabletop displays in study 2, where the shared space better supported group awareness compared to the personal workspaces. It has also been shown to be the case for individual users in study 1, with the good performance of Visual Trackpad.
The taxonomy of tool container location, however, shows there are other potential factors that make the outside workspace location desirable for tool containers. For example, there can be no occlusion of the workspace with outside location workspace, neither by the interaction (the finger, stylus, or embodiment – i.e., cursor) nor by the tool container. Also, outside workspace locations can better support bimanual interactions. The best motivating example of this is keyboard shortcuts, which are efficient once they are learned. Lastly, outside workspace locations can provide different input types and techniques than those offered to the user in the workspace. For example, LensMouse allows users to access toolbar items via direct input, and also supports regular indirect mouse input on screen. This example shows how tool containers should be paired with the best selection technique.
Interface designers should make use of the outside workspace location, because it offers properties that are not always available in the other two locations. Tool containers in this location can also be matched to the best selection technique, allowing users to make faster and more effective selections from them.
6.3.4 Which side of the individual-group tradeoff to support?
As proposed by previous researchers [31], users in collaborative environments must split their attention between attending to their individual work and attending to the group work. As shown in study 2, the location of the tool containers has a substantial effect on the ability for groups to coordinate their work: tool containers displayed in the shared space better support group awareness than tool containers displayed in the users‟ personal workspaces. These results can be interpreted in two ways.
First, some tool selections are important for all users to be aware of (for example, deleting a page from a shared document). These tools should be displayed in the shared space, because their
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selections are more likely to be noticed by other users. This is equivalent to choosing to support the group side of the individual-group tradeoff, because these selections are likely slower for individual users.
Second, some tool selections are either unimportant to other users (for example, using a magnifying glass to see more details) or are tool selections that users want to hide from others (for example, in a game). For these types of selections, designers may wish to specifically reduce the ability of other users to stay aware of these selections by choosing to support the individual side of the individual-group tradeoff. This would mean displaying these tool (and thus their tool containers) inside of the users‟ personal workspace.
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