[open] Showing multiple videos in one trial...and creating a datasource

KJO

Hi,

I've been struggling with this today and couldn't find much info on video experiments (most seem to use pictures etc.).
I'm trying to recreate an experiment that I built using another software package.

Basically, I want to show participants three videos per trial (the videos contain two people talking), after the third video I want to show a blank screen and then have the eye tracker track eye movements whilst a question (sound file) is played.

I want each of the three video clips per trial to appear in a particular order (i.e. always vid1, vid2 then vid3) but I wish to randomize the order of the trials themselves (i.e. three clips make up item 1, another three make up item 2 etc. and each item will be a different trial, presented in a different order to each participant)...

How do I create a database so that OpenSesame can extract the three videos relevant to each trial? I've done this in Experiment Builder before to gather pilot data, but I wish to use OpenSesame to run the actual experiment...

Also, I wish to do the same with the sound files so that the correct question for each item is presented after the three videos within the trial.

Any help or advice would be greatly appreciated,

K

Edwin

Hi K,

You could define the video files and the corresponding sound file within a loop item, e.g. in four variables: vid1, vid2, vid3, and snd.

The sequence that is associated with this loop, could look like this:

# NOTE: this is NOT code, this is an overview of
# how your trial block could be arranged!

loop # this is where you define your variables
-- sequence # this is used to run multiple items in a row
---- media_player_vlc_1 # play [vid1]
---- media_player_vlc_2 # play [vid2]
---- media_player_vlc_3 # play [vid3]
---- eyelink_start_recording # to start the recording of gaze position
---- eyelink_log # to log information about the current trial, e.g. which videos were shown and which sound was played
---- eyelink_log # to mark the start of sound playback
---- sampler # to play the sound file
---- eyelink_log # to mark the ending of sound playback
---- eyelink_stop_recording # to stop the recording of gaze
---- logger # to log trial data

The videos and sound files can be played in either the file pool of the experiment, or the directory in which the experiment is saved as well.

Further reading:

• sound playback
• video playback
• EyeLink documentation (tutorial PDF)

Good luck!

KJO

Thanks for your response!

Judging by what you've said above I'm glad to see that I'm on the right track...

The problem I'm having is that I can't seem to extract more than one row from the loop item when running the experiment on a test run. So the same three videos are being played each time and won't move onto the next row of videos (plus sound file).

Basically I want to have 30 separate rows (with three videos and a sound file each) that are played in a random order for each participant.

Also, I was wondering if there is a way to have two separate lists of data files that I could administer to participants? (i.e. List 1 has different videos than List 2 and a participant would receive only one particular list when they do the experiment...).

Thanks for any advice you can offer,

K