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Thread: interpretation of log file

  1. #1

    interpretation of log file

    Hello,
    I have an experiment in which I am showing multiple stimuli in each trial and recording reaction times.
    However i am finding it hard to interpret the log files:
    for every stimuli I get a response time e.g:

    1.1 stimulus_a 46ms
    1.2 stimiluls_b 81ms etc.

    so I think this is the response time for every stimulus in the set

    However at the end of each row there are also columns where it says:

    stim 1 time 1 stim 2 time 2 etc.

    and the times there are not the same times that i found before.
    so what is the real time? the one in the end of the row where it shows all of the stims and times, or maybe the times that are written in different rows?

    Thanks

  2. #2
    Join Date
    Nov 2005
    Posts
    3,328
    It's the first value that indicates the RT (i.e., in the RT column). The later (Time) values indicate how long the stimulus was on the screen. Since visuals need to be on the screen in multiples of the display's refresh rate, the display will usually be a tiny bit longer than the RT (e.g., 1 to 16ms for a 60hz display). Does that make sense?

  3. #3
    Not really. let me elaborate a bit
    every trial has a minmax value of 0-80! in every trial there are a few stimuli. a few have an RT value of 80, i.e. they are displayed for 80ms, and after those there are a few with an RT:any value. i.e. they appear for either 80ms (because of the minmax value) or until a button is pressed - whatever comes first. once a button is pressed i want to recrod the time and all that happens afterwards in not important for me.

    What i get in the log file is a row only for the stimuli that have a 'RT:any' value.
    and they are usually something like 81, 81, 81, 32. which means that three stimuli passed without a press of a button and then there was a press.

    in the 'time n' columns I get times for both the RT:80 stimuli and the RT:any and they are usually 33,33,33 for the 'RT:80' stimuli, then '100','100','100','42' for the 'RT:any' stimuli

    so it seems that the stimuili was on screen a time different than the one I have set. i can live with that as long as I can compute the time from the first 'RT:any' stimulus until the press of the button. But there is some contracdiction between the 'RT' column and the 'time n' columns

    I hope this is understandable
    thanks.

  4. #4
    Join Date
    Nov 2005
    Posts
    3,328
    Mmmm. Can you post your input file and a sample log output?

  5. #5
    yes I here they are. the stim is in hebrew though.
    Attached Files Attached Files

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