“In general, the path may have a complicated curvilinear shape (such as a spiral) with variable thickness W(s).

Simpler paths allow for mathematical simplifications of the general form of the law.”

so while a simpler form might be permissible in the case of constant width, the same law holds for all cases. In fact I’d argue that since youre pie shapes represent a tunnel with non-constant widths, they’d behave even less well for picking.

On the topic of apple’s dock, I don’t think it’s the *best* interaction approach, for a number of reasons. But one thing is certain – the effectively one dimensional scanning it provides seems far superior to the two dimensional scanning required for the rotating pie menu, especially considering there’s no root configuration in the pie menu (except when it’s first brought up.) That is – if I move the mouse out of the dock for some reason, everything is still where it was when I brought up the dock. The same is not true for the pie menu.

What happens if your attention is diverted while scanning the menu/dock? you turn to talk to a coworker or the phone rings. Say for argument’s sake you hit your mouse so the pointer is nowhere near the menu/dock.

When your focus returns to the screen, with a dock:

1) Locate your mouse pointer (wiggle mouse a bit, or use a cool compiz-like water effect, whatever)
2) Move mouse to the desired dock item location, which is always the same place.

With the pie menu:

1) Locate mouse pointer as above
2) Scan current pie menu configuration, since there’s no guarantee where things are
3) Move mouse to desired menu item

I’m not saying pie menus are bad – there’s plenty of literature that says they’re a good thing. All I’m saying is the rotating is bad. A rotating pie menu is *not* the same as (or anywhere near to) apple’s dock. Nor does it have all (or even many, I’d argue) of the benefits of pie menus.

Alex’s idea, with the menu items growing as the mouse approaches them (and presumably also shrinking the pies further away from the mouse) seems like a much better approach in terms of interaction, while simultaneously yielding cooler animation effects than simple rotation.

http://live.gnome.org/ScratchPad/CircularMenus

Maybe there is a chance that the ideas are combined? Would like to see this happen. BTW: I think that this is especially useful for children, people with disabilities and mbile devices where people dont use a keyboard.

This would very closely mirror the interaction of the OSX Dock, where approaching a target causes it, as well as closeby targets to grow larger and wider, in proportion to distance from the pointer.

Plus I think it would look wicked, a smoothly animated egg-like oval look as you extended deeper into a target. It’d also keep targets a bit more static so you could learn their positions. And the increased size would make it easier to see if you’re currently pointing to the right item.

Oh, and I’d make the pie pieces extend all the way to the center, or perhaps within just a few pixels of it. The utility of a pie menu is lessened if you have to travel ~20 pixels before you hit your first target (which is more than the height of at least one traditional menu item).

Something novel you might explore is to make the pie incomplete, taking up only the lower right 3/4 of a circle (in the case of right-handed pointers). Having the upper left 1/4 be open space would make it easier to dismiss an inadvertently opened pie menu.

Just food for thought

1, If the moving target is moving randomly or in a predictable way but away from the cursor, the time to acquire the target becomes erratic and the index of ease goes up dramatically. (Chasing cats)

2, If the moving target is moving toward the cursor the time to acquire the target decreases as long as the user is conscious of direction and the target they are reaching for. (reunited with a lover)

Don’t you think that if moving and scaling targets were a problem apple would have never used the dock? In all seriousness I think their interaction experts would have made it a big no no.

Your analogy isn’t even similar also, if you were to apply the analogy, the truth of it is that you are decreasing the length of the road. However this isn’t anything to do with steering, as the menu movement is in an arc (optimal movement of the wrist, least strain). Accot-Zhai steering law only really applies to cascading menus, where CORNERS are involved.

There’s also the derivation of Fitt’s law (mentioned on that same wikipedia entry): Accot-Zhai steering law, which draws a parallel between navigating through cascading menus on a display and travelling through a tunnel.

it has a wonderful passage here:

” \frac{ds}{dT} = \frac{W(s)}{b}

which says that the instantaneous speed of the user is proportional to the width of the tunnel. This makes intuitive sense if we consider the analogous task of driving a car down a road: the wider the road, the faster we can drive and still stay on the road, even if there are curves in the road.”

Like the passage says, it makes intuitive sense. I would argue that it also makes intuitive sense that the instantaneous speed of the user is inversely proportional to the amount the tunnel moves. Sure, they may have less distance to travel with the mouse, but that doesn’t mean it’ll be any faster (or easier) to hit their desired target.

Karl: this looks Awesome! Also, this grey-on-white editbox text is unreadable. Any chance of using gold ol’ black-on-white?

– Chris

“It describes untrained movements, not movements that are executed after months or years of practice”

“Pie menu items typically are selected faster and have a lower error rate than linear menu items, for two reasons: because pie menu items are all the same, small distance from the centre of the menu;”

– good ol wikipedia

Also reducing the law to the simplest description, the time to a target is a function of the size and distance to the target.

In the same way Apple exploit the changing distance (and size) in the dock menu, I have exploited this in fittsmenu.

You seem to be bringing up the same argument as mentioned in number 4 of this analysis of the OSX dock

http://www.asktog.com/columns/044top10docksucks.html

and although I agree with it in some respects, I also disagree believing that something visually stimulating is preferable to something which is proven to cause RSI. For instance fittsmenu is appropriate in situations like the one mentioned by Kevin, where designers are having to make repetitive dramatic movements to acquire the target of the toolbox to change tools.

For example, if I however to an icon in the bottom left, and then realize I need the icon in the top left, the top left icon will change locations if I try to move immediately to it. While the rotation may decrease the literal distance between my mouse and the desired icon, it increases the amount of time I must spend overall by requiring radial motion locked to the chosen rotation speed rather than simply moving to the new icon.

I suspect you’ll see this distortion if, rather than browsing the pie menu, you decide to jump between two icons that are one or two apart. Doing that accurately and quickly seems like a chore.

Its pretty much a circlular dock menu in that respect. Also the counter rotation helps with using the pie menu near screen edges.