Millisecond Forums

Can I change the way 'latency' is determine, or better yet, have different types of latency per trial?

https://forums.millisecond.com/Topic17020.aspx

By mvanrooij - 8/26/2015

Hi all, I'm using openended trials in which participant are instructed to respond by typing in the correct answer to a simple math problem like
'1 + 3 = ', followed by pressing 'ENTER'.

If I'm not mistaken, the latency that is collected for each trial, is the time between the start of the stimulus presentation to the moment of pressing 'ENTER', which is fine. However, I'm also interested in the time between the start of the stimulus presentation and the actual typing of the answer, i.e., the time until the first keyboard button press (not 'ENTER'). I therefore have to following two questions:
1. Is it possible to measure latency between the start of the stimulus presentation and the first keyboard response?
2. Is it possible to determine and record more than one latency, i.e., latency1 and latency2, per trial?

Thanks!
By Dave - 8/26/2015

Re. #1: Log the <openended> element's firstcharlatency property to the data file (or save it to a variable you log to the data file). There is also lastcharlatency; for further details see the language reference for the <openended> element / its properties).

<openended myopenended>
...
</openended>

<data>
/ columns = [..., response, latency, openended.myopenended.firstcharlatency, ...]
...
</data>

Re. #2: Generally no, with some trickery maybe. See e.g. this thread for an example: https://www.millisecond.com/forums/FindPost15812.aspx