The Malt, like a standard keyboard or most "flat" keyboards, uses a sideways striking type of thumb movement (flexion of the trapeziometacarpal joint at the base of the thumb). Some other "ergonomic" keyboards don't get the orientation right, but parallel to the other keys is close enough.
Maybe, but this hasn't really been studied and there aren't enough users to know whether or not such implementations will cause potential issues in the long term (anecdotally there are already some complaints).
Thumb keys have the big advantage that they can often be independently typed or held alongside finger keys on the same hand, but this isn't an essential limitation. For example finger modifiers can put the keyboard into an alternate mode (not needing to be held down).
This is factored into my analysis. Whether or not the thumb keys are used as so called 'one shot' modifiers is irrelevant. The problem is that once you include modifiers and real computer use the equation changes and complicates the analysis.
Alternately, if both hands are assumed to stay on the keyboard (for one-handed operation constraints are different), theoretically a single thumb modifier on each hand is enough; finger keys on the same hand can be used alongside as additional layers or modifiers, affecting keystrokes pressed on the other hand. Standard layer-switching with dedicated separate layer keys is arguably a waste of space.
This sort of chording has ergonomic implications that would have to be factored into the model. Intuitively this seems like it would involve a lot more strain than having dedicated keys for alt/ctrl/other layers.
Quote Colemak DH/Dvorak These are both suboptimal. They are built on outdated and limited assumptions about both physical keyboard shape and the way typing motions work (e.g. Dvorak is designed for mid-20th-century typewriters which are substantially different from any currently available computer keyboard). However there are diminishing returns to improvements in letter layout, so any of them is a reasonably acceptable alternative to QWERTY.
It is not self evident that layout optimization for typewriters dramatically differs from the optimization criteria for computer keyboards when typing English text. Even if you believe this it is not clear what the optimization criteria should be or whether or not any appreciable gains can be made over common layouts like Dvorak or Colemak.
i think that one of the motions that we should be doing a lot with our hands that we never do with keyboards is gripping with all fingers and the thumb at the same time. this motion sort of resets the whole mechanical system of the joints and ligaments. i have no empirical data on it, but i have a feeling it can prevent rsi, because doing heavy free weights helps against this, and that includes gripping stuff very hard. so it would be interesting to me how to make a layout where you grip an object a lot. note this is different than a pinching motion (eg when putting salt on something), and it's different from making a fist. But it's more like making a fist than anything - it's just that the thumb doesn't go over the fingers, but instead the tip of the thumb meets the tip of the other fingers.
i think the important part here is that all five digits close at the same time, rather than just thumb + one of the other fingers at random, but maybe having pairs (combinations of thumb and single finger) can be helpful in itself.
note that you don't really need to touch the tip of your thumb to the tips of the other fingers, just going part of the way will be helpful.
maybe the following system could help:
1. keyboard is shaped like a convex object which you grip, eg a ball or bar (cylinder) or upside down bowl
2. thumb operates shift
3. if you want to type a shifted version of a key, you press the thumb, then the key, and it will only get typed once the thumb is let go again
4. shifting is per side. so left shift only interacts with the left side of the keyboard, right with right side. you could be holding right thumb shift, and still typing lower case characters with the left hand, and those letters would get typed as soon as you pressed the key, not after releasing the thumb.
5. space is on thumb + multiple keys. any keys are fine, just more than one. alternatively that could be enter. not sure which is better, but space gets typed more, so you'd be doing the gripping motion more.
6. you have another shift on either side somewhere that can be operated like normal shift: bilateral, things get typed as soon as you press them.