[solved] understanding log data for RT task

atrop21

Hello,
this is my first post to the forum- thanks to the opensesame crew for an amazing program! its been so helpful.

quick description of my exp: I've been setting up a lexical decision task. my experiment includes (4 blocks of) looped trial sequences (looped 40 times). within the trial sequence there is a sketchpad item with a stimulus presentation followed by keyboard_response, which contains the key response time to the experimental stimuli. after each loop (ie after every 40 trials), I have a form_text_input.

In reading the data, I noticed that once the text input is logged, it repeats in the spreadsheet until the end of the experiment. this is no big deal but is there a way to make that stop?

More importantly, the data for item response_time_keyboard_response seems to repeat once at the end of each loop, i.e. corresponding to the running of form_text_input. Is this because response_time_keyboard response is just repeating itself in the absence of a new keyboard response? or, as i am concerned, is it possible that the response time logged is not corresponding directly to the RT to the experimental stimuli?

thanks!

Edwin

Welcome to the forum!

In general, the logfile contains a column for every single variable. Each row in the logfile is made on an occurrence of a logger object in your experiment. Usually, you use one logger per trial, resulting in a single line per trial in your logfile (which is most likely what you want).

When there is no new value for a variable, then the same value will be logged in consecutive trials. An example: if you log the variable subject_nr it will always show the same subject number, as it isn't updated during the experiment. The same goes for a variable that is only updated every 40 trials, like the result of your form_text_input: it simply does not change, so the logged value is the same in each trial, and thus in each row in your datafile.

The fact that the value for response_time_keyboard_response is repeating with the occurrence of your form_text_input leads me to believe you've added a logger after the text input, which would write a new row in the datafile, containing the (unchanged!) timestamp of the keyboard response.

To reset a variable, you could add a little bit of inline scripting:

exp.set("response_time_keyboard_response", "")

If you add this example to the Run Phase of an inline_script, it will set the value of response_time_keyboard_response to an empty string.

If you still have any questions after reading my post, the documentation page on logging data with OpenSesame's logger item is a must-read!

Good luck!

Edwin

atrop21

Hi,

Thanks for clearing things up! I do have a logger after the form_text_input, you are right!I'll try that in-line scripting and let you know. Either way its cool bc its just a little meaningless extra data, I suppose