Direct RT V2008 lagging speeds to display stimuli (case 16596)

[jason_reed]

Could you please upload a copy of your .csv input file and the short and long (i.e. log) output files it produced? I would like to take a look at them to see exactly how the timing breaks down for each stimulus and trial.

[fiona wixted]

Hi,
I have attached the csv and log files. Let me know if you need anything else. There are two more images (o and D which are also 500kb files) which would not upload as they are too big

Thanks
Fiona

Could you please upload a copy of your .csv input file and the short and long (i.e. log) output files it produced? I would like to take a look at them to see exactly how the timing breaks down for each stimulus and trial.

[fiona wixted]

I have attached two more images (o and D) here that I'm using to run the AVT test.

Thanks
Fiona

[jason_reed]

Could you please also upload a copy of the styles.drt file you use?

[jason_reed]

Please also tell me the screen refresh rate options you have for your monitor. You can find instructions for your Windows OS here: http://www.microcentertech.com/tech_...OW8003892B.htm. Please be sure to tell me all the options in the dropdown menu as well as the one you used when you actually ran your DirectRT files.

[fiona wixted]

Hi,

My refresh rate options for True Colour are 60 Hz or 75 Hz but I have tried varying the refresh rate and it hasn't had an impact on the test timing. I have attached the styles.drt form. The refresh rate was set at 60 Hz when I ran the test initially. Any ideas on what I could try to reduce the lag time?

Thanks a million,

Fiona

[jason_reed]

After taking a look at all the files, I have some thoughts on two aspects of your project.

First, there's the point about presenting two images (i.e., a letter.bmp file and the blank.bmp file) at the same time for a specific amount of time (i.e., 40ms). As discussed in the DirectRT manual section about screen refresh rates (http://www.empirisoft.com/directrt/h...y_concepts.htm) DirectRT " will display your stimulus for as many screen refreshes as it takes to come closest to your requested display time and will create a log data file for you so that you can compare requested against actual presentation times." So your ms per refresh would have to be a divisor of the desired display time; in your case, the ms per refresh would need to be something like 20 ms per refresh for your desired 40 ms display time. One thing you can do is to check the ms per refresh (1000/screen refresh rate) for different screen resolutions to see if the meet this criteria. Otherwise, DirectRT will do its best to display stimuli for the requested number of ms in the input file based on the screen refresh rate.


Second, there is your desire to have the six two-minute intervals; I assume this corresponds to trials 2-7 in your Fiona Script.csv file. You could control this by using a style code in the style column of the Fiona Script.csv file that has 0-120000! to stop each row of it after 2 minutes pass from the time the first stimulus in each row of your input file is presented. You can also use a different style code between <> to keep the automatically moviing on to the next stimulus for your keypresses like it describes here in the DirectRT manual here: http://www.empirisoft.com/directrt/h...ctrt_style.htm. See the attached styles file and Fiona script styles.csv file for an example.


Alternatively, you could use the meta column feature (see http://www.empirisoft.com/directrt/h...a_commands.htm) to create the same 2 minute time limit for each of row of your input file. Take a look at the attached Fiona script meta.csv file for an example that tells DirectRT to move on to the next trial after 2 minutes has passed. As with the styles code option, this should move on 2 minutes after each row of your input file starts regardless of whether the participant has progressed through everything in each row of the trial.