I suspect such a study to have any validity would have to involve a rather large group of participants given the variables of anatomy, age, experience, etc.. The more controls you need to nail down a reasonably definitive answer to the questions you pose, the larger the group, the greater the expense. Assuming you don't have a private group with millions of dollars, you have to find researchers willing to spend the time to write the grant and find an agency willing to fund the research and that means justifying the tax dollars spent to someone. If you are not in a sexy field of research, you rarely get a grant that pays little more than your salary, the rest is done a shoestring budget (I have a friend that goes dumpster diving at corporations for glassware and hardware. :-) )
I took at look at http://www.informaworld.com/ just because I had no idea where to look ergonomic science so I googled. Interesting what I found, people actually are do some studies on typing in reference to RSI, but the studies are small and address questions of posture. I was surprised to find a study that is actually trying to come up with relevant measures. How success this particular approach is I have no idea.
Human-Computer Interaction, Volume 17, Issue 2 & 3 September 2002 , pages 271 - 309
Empirical Bi-Action Tables: A Tool for the Evaluation and Optimization of Text-Input Systems. Application I: Stylus Keyboards
Authors: Dominic Hughes; James Warren; Orkut Buyukkokten
Affiliation: Stanford University.
We introduce a technique that, given any text input system A and novice user u, will predict the peak expert input speed of u on A, avoiding the costly process of actually training u to expert level. Here, peak refers to periods of ideal performance, free from hesitation or concentration lapse, and expert refers to asymptotic competence (e.g., touch typing, in the case of a two-handed keyboard). The technique is intended as a feedback mechanism in the interface development cycle between abstract mathematical modeling at the start (Fitts' law, Hick's law, etc.) and full empirical testing at the end.
The utility of the technique in iterative design is contingent on what we call the monotonicity principle: For each user u, if our prediction of peak expert input speed for u is higher on system A than on system B, continuous text input by u after training to expert level will be faster on A than on B. Here, continuous refers to actual real-world use, subject to errors, physical fatigue, lapses of concentration, and so forth. We discuss the circumstances under which monotonicity is valid.
The technique is parametric in the character map-that is, in the map from actions (keystrokes, gestures, chords, etc.) to characters. Therefore, standard heuristic algorithms can be employed to search for optimal character maps (e.g., keyboard layouts). We illustrate the use of our technique for evaluation and optimization in the context of stylus keyboards, first benchmarking a number of stylus keyboards relative to a simple alphabetic layout and then implementing an ant algorithm to obtain a machine-optimized layout.
and then there is this
http://www.leaonline.com/doi/abs/10.120 … 1hci1104_2
TYPIST: A Theory of Performance in Skilled Typing
I can't read this paper without buying the article but here is the authors website
Here is a rather old small study (1981, N=6) that points out a problem to consider in constructing a learning study.
http://stinet.dtic.mil/oai/oai?verb=get … =ADA103437
"Six skilled typists were studied while they transcribed English text. The typists showed stable patterns of performance, but with significant individual differences among the typists. Inter-Keypress latencies for 2-finger digraphs (typed by two fingers on the same hand) were particularly variable among typists. Two typists showed large differences in 2-finger digraph latencies, but similar overall typing speeds. Finger movement trajectories, determined from analysis of videotapes of these typists, indicated that the differences in 2-finger digraph latencies correspond to differences in the independence of within-hand finger movements. A high-speed film of one typist showed that finger movements of this typist almost always overlapped. The starting times of movements were six times as variable as the ending times, suggesting that it is the completion rather than the initiation of the movements that is controlled in skilled typing. These studies demonstrate the importance of considering individual differences in constructing a theory of skilled human performance, even in a highly automatized task such as transcription typing."
another relative old publication