Cumulative RT for Two Events

[David McFarlane]

Jordan,

OK, just for the sake of the record, let's see if I understand your 
design.  Here is the timeline I imagine:

- Stim1 is presented to subject
- subject responds, producing Stim1.RT
- some time intervenes, whether we want it to or not
- Stim2 is presented to subject
- subject responds, producing Stim2.RT

And you call the sum Stim1.RT + Stim2.RT the "cumulative" RT.

Well...  I would *not* by any means call that a "cumulative" RT, that 
seems to me to fight against the ordinary sense of the term 
"cumulative".  To me, "cumulative" refers to a sum with no intervening 
gaps, which you do not have here.  For instance, if I set my trip 
odometer to 0 and drove errands to the grocery store, the hardware 
store, and the filling station, I might say that I drove 0.5 miles to 
the grocery, 1.5 miles to the hardware, 0.5 miles to the filling 
station, and 1 mile to home, for a cumulative distance of 3.5 miles. 
But I would *not* say that the cumulative distance for the grocery and 
filling station segments was 1 mile, that would just be a weird use of 
the term "cumulative".  I might instead say that the *sum* distance for 
the grocery and filling station segments was 1 mile.

So what you mean instead is a mere sum of RTs, not a "cumulative" RT, so 
why not just say that?  Words are important my friend.

And once again, if you are to proceed in this line of work then you 
must, MUST, thoroughly study Chapter 3 of the User's Guide.  I cannot 
stress that enough.

-- David McFarlane, Professional Faultfinder


Jordan Schoenherr wrote:
> Hi David,
> 
> I'll definitely check this out. Concerning my meaning, I have two
> successive events and I want to sum the RT for event 1 and event 2 to
> create a cumulative RT.
> 
> On Sep 22, 5:27 pm, David McFarlane <mcfar... at msu.edu> wrote:
>> Jordan,
>>
>> Just making sure...  Please be advised that "Cumulative" timing mode
>> does *not* in any way, shape, or form produce a "cumulative RT",
>> whatever that means.  Cumulative timing mode only affects how E-Prime
>> schedules the onset time of the next object.  For details, study Chapter
>> 3 of the User's Guide that came with EP; you might also look at my
>> earlier post, "Mastering E-Prime: Meaning of all time audit measures" athttp://groups.google.com/group/e-prime/browse_thread/thread/39e899d34...
>> .
>>
>> -- David McFarlane, Professional Faultfinder
>>
>>
>>
>> Jordan Schoenherr wrote:
>>> And now for my final realization: if I turn off the logging function
>>> for the second event, that should do the trick.
>>> On Sep 22, 5:00 pm, Jordan Schoenherr <psychophysics.... at gmail.com>
>>> wrote:
>>>> I'll just post on my own thread:
>>>> So it seems that each event that is given a cumulative value is placed
>>>> in the RT recording sequence and RT feedback is provided for the final
>>>> event. I'm still interested in whether I can use the acc from the
>>>> first event in the feedback sequence?
>>>> On Sep 22, 4:25 pm, Jordan Schoenherr <psychophysics.... at gmail.com>
>>>> wrote:
>>>>> Hi All,
>>>>> As my subject indicates, I'm interested in obtaining the RT for two
>>>>> successive events individually and cumulatively. The latter will be
>>>>> used for feedback but have accuracy ONLY for the first event. Now,
>>>>> from what I can tell, the experiment 'NestingXRT' provides an example
>>>>> of how this can be accomplished.
>>>>> In the second event, 'time audit only' is selected in the duration/
>>>>> input window data logging and 'cumulative' is selected in the data
>>>>> audit window. From what I can tell, this would seem to mean that this
>>>>> event retains information from the previous two ('stimulus 1' and
>>>>> 'stimulus 2'), however, I'm more concerned about where the
>>>>> accumulation process starts and how this is specified.
>>>>> In short,
>>>>> 1) I want to record each event individually;
>>>>> 2) I want to have a way to obtain the cumulative RT for events 1 and 2
>>>>> (but not fixation or anything else that precedes the stims);
>>>>> 3) Present RT feedback based on cumulative RT (but accuracy only for
>>>>> the first event).
>>>>> Any help would be of great assistance!
>>>>> Cheers,
>>>>> Jordan

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