Aucb.157
fa.editor-p
utzoo!decvax!ucbvax!C70:editor-people
Thu Dec 10 12:57:42 1981
Re: Cross-Product Languages
>From Moran@PARC-MAXC Thu Dec 10 12:55:12 1981
DLW: If a user really can really push Control and Meta together, ie, as a
simple chord, then I think that this action can be approximated as a single
keystroke. So, Control-Meta-D would be two keystrokes -- for a user who has
developed the skill to do this chording, which is not part of normal typing
skill. Of course, typing n Meta-Control-F's in a row takes n+1 keystrokes,
since the Meta-Control only has to be pushed once (or n+2 for a user who
cannot chord).
JQJ: We are talking only about speed, not ease, here. And we are talking
only about skilled users. Also, we are only considering the time to execute
physical actions (key presses) and ignoring any mental time. A skilled
keystroke sequence will probably require mental preparation operations, which
we call M operations in our model. Since these are about 1.5 sec a crack (ie,
equivalent to about 5-8 keystrokes each), it is important to consider whether
a keystroke sequence requires them (clipping a keystroke or two at the expense
of incurring an M operation is not a good tradeoff). Check the
Keystroke-Level Model paper for details about the heuristics for determining
where M operations go in a command sequence. The notion of "ease" is, I would
assert, more bound up with these mental operations than with the physical
keystroke operations. But ease is not an operationalized concept and seems to
refer to several underlying psychological factors. For example, I intuitively
feel that a single touch-typing keystroke command is qualitatively "easier"
than a two-keystroke command, far beyond the extra keystroke time (and there
is usually no extra mental operation required for a two-keystroke command).
GS: (1) Your points about EMACS are interesting. The notion of consistency of
commands is quite subtle, and we don't have a good theory. I know of only a
couple of papers proposing psychologically-oriented grammars that might capture
some of the notion. The grammatical notion of consistency usually only deals
with commands as content-free symbol (for action) sequences. What your
Transpose-Word example points out that there is also an aspect of a command
sequence being "consistent" with the task it is supposed (assumed) to perform.
The tradeoffs between the various aspects of consistency are not understood.
(2) In skilled typing, the fastest keystrokes occur between hands (about 25%
faster than than keystrokes within hands). Typing the same key twice is
basically no faster than typing any other within-hand keystroke pair.
Tom Moran
-----------------------------------------------------------------
gopher://quux.org/ conversion by John Goerzen <
[email protected]>
of
http://communication.ucsd.edu/A-News/
This Usenet Oldnews Archive
article may be copied and distributed freely, provided:
1. There is no money collected for the text(s) of the articles.
2. The following notice remains appended to each copy:
The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996
Bruce Jones, Henry Spencer, David Wiseman.
