[ACT-R-users] Model of writing

[Michael Carl]

thanks very much for the program and the literature pointer (I will go through
it)! I have run Dan's peck-test lisp model. The ACT-R press-key action
in the lisp code
produces "rt" in 900ms and the peck actions for the same string takes 700ms.
Comparing this to our (Danish) data: there are two peaks in the duration
distribution for "rt": one around 75ms and another one around 180ms (there are
more instances at the second peak), while for instance the most frequent bigram
"er" (on the keyboard just to the left of "rt", and more likely typed with two
fingers) has most occurrences around 60-90ms. A frequent trigrams like "ing"
(even in Danish:-) is most of the time produced in 230-250ms and we also have
some 6-grams produced in less than 600ms (always for n-1 inter-keystroke
intervals).

In principle, if two or more fingers are involved there could be any time lapse
between the keystrokes, zero and even negative when the keys occur in the
reverse order e.g. frequent typo hte (but maybe you would model that
differently). If you splash both hands on the keyboard then almost all keys
could be produced simultaneously - all of which shows that typing actions go
on in parallel as Susan mentions.

There does not seems to be an easy way to simulate something like this in
ACT-R, even if we have the distributions and given also that there is no
indication which fingers were used for a particular typing event in our data.

Any suggestions?

Michael


2010/8/24 Bonnie John <bej at cs.cmu.edu>:
> Susan, what you say is certainly true, but adding my own bit of history,
> part of my thesis compared my serial approximation to the Rumelhart and
> Norman PDP model and I matched the inter-keystroke time for digraphs
> better than they did. My serial model had an average absolute percent
> error of 0.9% and theirs was 5.7%.
>
> That part of my thesis used a model of each finger's position and a very
> simple approximation of where all the fingers on the hand move to when
> one finger hits a key. Then it just used Fitts Law for the horizontal
> movement to the next key. This is at a lower level than what we are
> currently doing in CogTool/ACT-R, but it could be done in ACT-R if we
> programmed the fingers to know where they are in space and move
> according to the algorithm in my thesis. Anybody want to implement that?
>
> Bonnie
>
> Reference for the serial typing algorithm:
> John, B. E. (1996) TYPIST: A Theory of Performance In Skilled Typing.
> Human-Computer Interaction , 11 (4), pp.321-355.
> Figure 16 and 17.
> The PDP model I compared to was in
> Rumelhart, D. E. & Noman, D. A (1982) Simulating a Skilled Typist: A
> Study of Skilled Cognitive-Motor Performance. Cognitive Science, Volume
> 6, Issue 1, pages 1–36.
>
>
> Susan Chipman wrote:
>> I thought I might remind people that typing was one of the first
>> behaviors modeled by the PDP folks. They had data showing that
>> multiple typing actions went on in parallel -- that is, the actions of
>> future fingers were beginning before the current action was completed.
>> Don't know if these ACT-R models are dealing with that.
>>
>> Susan Chipman
>>
>> On Tue, Aug 24, 2010 at 3:29 PM, <db30 at andrew.cmu.edu
>> <mailto:db30 at andrew.cmu.edu>> wrote:
>>
>>
>>
>>     --On Tuesday, August 24, 2010 1:18 PM -0400 Bonnie John
>>     <bej at cs.cmu.edu <mailto:bej at cs.cmu.edu>> wrote:
>>
>>         We have a lower-level model of typing implemented in ACT-R tht is
>>         "under-the-hood" of CogTool. It is a mixture of my ages-old
>>         PhD thesis
>>         and what we cold do in ACT-R without changing the entire
>>         structure of
>>         its hand and fingers. So it still has remnants of ACT-R's typing
>>         assumptions, like the the hand always goes back to the
>>         home-row between
>>         each keystroke, but we have relaxed some of the other
>>         assumptions in the
>>         standard ACT-R typing model and so have sped it up to being
>>         about a 40
>>         wpm typist instead of the 20 wpm typist it is in the general
>>         release.
>>
>>
>>     One note to make about that is the only assumptions about fingers
>>     returning
>>     to the home-row are with the use of the press-key and peck-recoil
>>     actions.
>>     If one programs the specific finger movements with peck and punch
>>     actions
>>     then the fingers will stay at the key that was hit. If you're not
>>     already
>>     taking advantage of that you may be able to speed up your CogTool
>>     typist
>>     even further. Of course the complication is that to do that you would
>>     also have to have something that computes the necessary geometry
>>     from the
>>     current finger position to the target key instead of just the
>>     home-row to
>>     target key geometries which are available from press-key.
>>
>>     As a simple demonstration of that, attached is a simple model
>>     which types
>>     two keys in sequence using the same finger twice. The first time using
>>     two press-key actions and the second using explicit peck actions. The
>>     inter-key time for the second pair is less than for the first and that
>>     should be true for all valid one-finger pairs.
>>
>>     Dan
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