From: mike@isgtec.com (Mike Sellers)
Newsgroups: comp.windows.x,comp.human-factors
Subject: Typing, reaction times, and users (was Re: GUIs Considered Harmful)
Date: 10 Sep 92 13:27:04 GMT
Followup-To: comp.human-factors
Organization: ISG Technologies Inc., Mississauga Ontario

Note the followup-to line.

In article <1992Sep08.215240.49778@ans.net> db3l@ans.net (David Bolen) writes:
| In article <3243@isgtec.isgtec.com> mike@isgtec.com (Mike Sellers) writes:
| >mouse@thunder.mcrcim.mcgill.edu (der Mouse) writes:
| >> Oh, the subjects were just basically incompetent in general.  If it
| >> takes as long as *one* second to decide which key to press, I consider
| >> myself "idling".  I type well over 100wpm when I don't have to stop and
| >> decide what I want to type next.  If I know what I want to do, and what
| >> key I need to press to do it, it will eat up perhaps .05 second.
| >Unless you've had yourself independently timed, I doubt strongly whether
| >_any_ of these numbers are correct -- I think a reaction time of 0.05 second
| >may be impossible ...
| 
| On the other hand - why are these numbers so off?  

First of all, typing speeds in excess of 100wpm are rare and are definitely
at the far end of the bell-shaped curve.  Legal secretaries are required to
type in the 80+wpm range; most engineering folks type in the 30-60wpm range.
(Then too, typing speeds differ on typewriters and computers, especially
when you take mistakes into account.)  Others who type less for a living
generally have lower typing speeds.

Second, typing as a learned skill is different from a cognitive behavior.
Minimum reaction times where attention and cognition (decision) are involved
are _at best_ about 0.3 seconds for very simple tasks ("press the button if
the second letter you see is the lowercase version of the first letter you
see").  This RT decreases as the cognitive loop is removed, down to a
lower limit of around one action per 0.075 second; this is approximately
the physical limit provided by the nerves and muscles of the hand and finger.
This is roughly consistent with typing speeds of 150-200 wpm (5 letter word, 
not 4, btw).  I think the world record for typing speed is just over 200wpm.

| Now if I can type (think, move fingers, depress key, etc..) a character in
| 0.1s, why can't my reaction time component of that be in the .05s range?
| Maybe I'm at the high end of the typing spectrum (actually, I'm pretty sure I
| am), but not unrealistic.

Expert typing does not require conscious attention, just as signing your
name with a pen does not (once you're beyond elementary school, anyway :-) ).
When you type at speed, you do not think about which fingers are moving
where, as they do not require the conscious control that they do for a task
requiring attention and decision.  Thus, reaction times of about 1 second
are, contrary to the first poster's assertion, at least average if not
slightly above average for that kind of task.

| >On the other hand, if you really do type "well over" 100wpm then you are
| >at the far end of the typing-speed spectrum.  Given this, your needs and
| >abilities do not conform to the needs and abilities of the vast majority 
| >of computer users; you cannot judge them by looking at yourself.
| 
| Ok, maybe I'll buy that.  But that doesn't invalidate either of our thoughts
| on the use of rodents (I happen to strongly agree with der Mouse (is that a
| proper name?) in this area), does it?

Not for users like you, no.  However, you are a definite minority, and are
unlikely to be the focus user of any major software products.

| My personal opinion has always been that I don't mind the mouse so much (it
| can even be helpful if I've been away from a program for a while), but 
| please, please, please, please be sure and give me a keyboard shortcut so 
| I don't *have* to use it.  Especially if the application involves text 
| input and manipulation.

Multiple channels of input should certainly be supplied, including text 
shortcuts if the users are at all likely to employ the keyboard.  This
does not invalidate the use of the mouse for many other users.




--
              Mike Sellers      User Interface Team Leader
           mike@isgtec.com      ISG Technologies, Toronto, Canada
              "Actum ne agas" -- Do not do what has been done.
                         Furare tantum ab Optimis
Newsgroups: comp.windows.x