I'm struggling to create a study in which subjects are asked to rate a series of faces on a Likert scale while in the background is played a sequence of random sounds. Specifically, I don't understand how to create a pool from which randomly picking out one sound per time until the end of the block. I don't want to set any limit to the sampling of sounds, just to be sure that the subject listens continuously to a random series until he rates all the faces of the list.
######items##############################################################
<item pictureitems>
/ 1 = "c0_p1_t2.jpg"
/ 2 = "c0_p1_t-2.jpg"
/ 3 = "c0_p1_t3.jpg"
/ 4 = "c0_p1_t-3.jpg"
/ 5 = "c0_p2_t2.jpg"
/ 6 = "c0_p2_t-2.jpg"
/ 7 = "c0_p2_t3.jpg"
/ 8 = "c0_p2_t-3.jpg"
/ 9 = "c0_p3_t2.jpg"
/ 10 = "c0_p3_t-2.jpg"
/ 11 = "c0_p3_t3.jpg"
/ 12 = "c0_p3_t-3.jpg"
/ 13 = "c0_p4_t2.jpg"
/ 14 = "c0_p4_t-2.jpg"
/ 15 = "c0_p4_t3.jpg"
/ 16 = "c0_p4_t-3.jpg"
/ 17 = "c0_p5_t2.jpg"
/ 18 = "c0_p5_t-2.jpg"
/ 19 = "c0_p5_t3.jpg"
/ 20 = "c0_p5_t-3.jpg"
/ 21 = "c0_p6_t2.jpg"
/ 22 = "c0_p6_t-2.jpg"
/ 23 = "c0_p6_t3.jpg"
/ 24 = "c0_p6_t-3.jpg"
</item>
<item soundsitems_threat>
/1 = "threat1.mp3"
/2 = "threat2.mp3"
/3 = "threat3.mp3"
</item>
<item soundsitems_neutral>
/1 = "neutral1.mp3"
/2 = "neutral2.mp3"
/3 = "neutral3.mp3"
</item>
<item soundsitems_negative>
/1 = "negativw1.mp3"
/2 = "negative2.mp3"
/3 = "negative3.mp3"
</item>
#video and picture elements###############################################
<picture faces>
/ items = pictureitems
/ position = (50, 40)
</picture>
<video sounds_threat>
/ erase = false
/ items = soundsitems_threat
/ playthrough = true
/ selectionrate = block
/ resetinterval = 0
/ size = (2,2)
/ position = (1,1)
/ select = noreplace
</video>
<video sounds_neutral>
/ erase = false
/ items = soundsitems_neutral
/ playthrough = true
/ selectionrate = block
/ resetinterval = 0
/ size = (2,2)
/ position = (1,1)
/ select = noreplace
</video>
<video sounds_negative>
/ erase = false
/ items = soundsitems_negative
/ playthrough = true
/ selectionrate = block
/ resetinterval = 0
/ size = (2,2)
/ position = (1,1)
/ select = noreplace
</video>
###########################trials########################################
<likert face_rate>
/ stimulusframes = [1=faces]
/ position = (50, 80)
/ anchorwidth = (10%)
/ anchors = [1 = "DISONESTO"; 4 = "Né DISONESTO Né ONESTO"; 7 = "ONESTO"]
/ buttonvalues = [1="-3", 2="-2", 3="-1", 4="0", 5="1", 6="2", 7="3"]
/ numpoints = 7
</likert>
################blocks######################################################
<block threat>
/ trials = [1 - 24 = noreplace(face_rate)]
/ preinstructions = (instruction)
/ postinstructions = (post)
/ bgstim = (sounds_threat)
</block>
<block neutral>
/ trials = [1 - 24 = noreplace(face_rate)]
/ preinstructions = (instruction)
/ postinstructions = (post)
/ bgstim = (sounds_neutral)
</block>
<block negative>
/ trials = [1 - 24 = noreplace(face_rate)]
/ preinstructions = (instruction)
/ postinstructions = (post)
/ bgstim = (sounds_negative)
</block>
################experiment##################################################
<expt face_sounds>
/ blocks = [ 1-3 = noreplace(negative, threat, neutral); 4= Demographic]
/ preinstructions = (intro_1, intro_2)
/ postinstructions = (end)
</expt>