[ACT-R-users] EMMA question (bug?)

["Marc Halbrügge"]

Dear Dario and list,

> I'm not sure what constitutes "short" encoding times for you, but  
> certainly the shorter they are, the more skipping you should observe.
well, I could have been more specific here, you're right ;)

When encoding times are short (compared to eye movement times), then the overall reaction time is mostly determined by the number of saccades needed. 
In this case, EMMA does not work well. The time needed for the (last) saccade to the target is disregarded when recog-time<total-time but recog-time>fprep-time

> I'll run some further tests with this and we'll be in touch.  
Thanks

Greetings
Marc


> 
> Best,
> Dario
> 
> 
> On Jul 9, 2008, at 4:39 PM, Marc Halbrügge wrote:
> 
> > Hi,
> >
> > while modeling some visual search behavior, I ran across the  
> > following problem:
> >
> > Salvucci (2001) states that "EMMA can produce skipped gazes by  
> > canceling
> > saccades when encoding occurs quickly (i.e., before eye-movement  
> > preparation is complete)"
> >
> > but the ACT-R module skips gazes much too often when the encoding  
> > time is short. I tracked that down to line 391 in method initiate- 
> > eye-move:
> >
> > (when (<= recog-time (total-time sacc-mvmt))
> >  (schedule-event-relative (max 0 recog-time)  'ENCODING- 
> > COMPLETE   ;;mjs
> >
> >
> > I my opinion, this should be (changes in bold)
> >
> > (when (<= recog-time (FPREP-TIME sacc-mvmt))
> >  (schedule-event-relative (max 0 recog-time)  'ENCODING- 
> > COMPLETE   ;;mjs
> >
> >
> > What do you think?
> >
> > Greetings
> > Marc
> 
> _____________________________________
> Dario Salvucci, Ph.D.
> Associate Professor
> Department of Computer Science
> Drexel University
> http://www.cs.drexel.edu/~salvucci/

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