Probe Task Samples and Documentation (case 1590)

The following samples demonstrate how to execute a secondary task or probe task while a subject completes another task in MediaLab. Visual, auditory and TTL signal probes can be launched at any time from your questionnaire. You can create a schedule of probes at either random or fixed intervals and get subjects' response times to the probes. The probes can span multiple items as the probe function runs independently of the experiment once launched. Response times are assessed using DirectX so their accuracy is very good.

I was able to get this close to functional pretty quickly but it is not recording every response to the probe items. Instead, I get a data file with the responses for about half of the items and a "read me" text file saying things like "Can't run probe set 4 because last probe set is still running". It doesn't seem connected to the number of trials I have in between probe sets. Some of the probe sets work fine on back to back trials while others, with several trials in between, give me that error message.

Any ideas?

Do the samples work ok on your machine? If so, send me a copy of your probe file and que file and I'll take a look at them.
-Blair

I trying to run the probe samples. The anagrams work quite fine but the essay don´t. ???
I changed the first items in the anagram file from picture to tone to test for tone but no sound was produced (although other sounds can be heard), rather the old version with the pictures appeared. How can this be? I deleted the old probe pictures in the excel file - they are not there.
So how do I get tone probes when your example tone(1000,500,3000) does not work?
Something obvious I missed?

Okay, I just found out that changes in an once saved file are not realized by MediaLab although the changes are visible in the .csv file.
So, after creating my own NEW probe.csv file I succeeded in auditory tone probes so far.
Thanks for the examples!
GC

We're running an experiment in which people are reading stories and responding to a auditory probe. The probes are working just fine but all of our data in the resulting probes.sav file shows up as -1 for the var_t, var_k, and var_r variables. We've tried different probe parameters with no success. Any advice is appreciated.

Do the samples work for you ok? I took a look at the files you sent to support, and I noticed the time ranges for the probes were a little odd. There should be increasing values because they are cumulative--not relative to the last trial (which is what it looks in your input file). The start time of a probe should never be less than the end time of the previous probe. Otherwise, there is no way to know which probe the subject is responding to. Does that make sense? I'm actually surprised that this approach doesn't send MediaLab into a meltdown. It would make sense to have MediaLab inform you of this automatically.

Good day, i need to know if any one can share installation tutorial for attentional probe task program. Would be very grateful.[B][COLOR=navy][FONT=Arial]
[SIZE=1]Regards, F.[/SIZE]

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Hello, I want to know if I can combine MediaLab's voice response feature with STRT reaction input? In the keycodes document there are only keyboard inputs, but I would like to have the participants give vocal responses to the audio probes during video watching and record their RTs. Has anyone done anything like this before? If the current Medialab version doesn't support it, what would you suggest as the next best option for me to do? Thank you very much!

"We're running an experiment in which people are reading stories and responding to a auditory probe. The probes are working just fine but all of our data in the resulting probes.sav file shows up as -1 for the var_t, var_k, and var_r variables. We've tried different probe parameters with no success. Any advice is appreciated."

I am having the same problem. The tones are playing and being responded to, but the var_t, var_k, and var_t variable show up as -1s. Any help would be greatly appreciated.

RCPRIME,

Are you still getting values of -1 with var_t and var_k variables in your study?