Millisecond Forums

## Selection and randomization of stimuli

https://www.millisecond.com/forums/Topic32238.aspx

 By SilvioM - 9/23/2021 Dear all, I have been working on an Inquisit script (please find it attached) and I am struggling with the stimuli selection. I have a block with four different types of trials: approaching stim_1 in the upper part of the screen with distractor_1; approaching stim_1 in the lower part of the screen with distractor_1; approaching stim_1 in the upper part of the screen with distractor_2; approaching stim_1 in the lower part of the screen with distractor_2. There are eight stimuli by category (ie eight stimuli for stim_1 ; eight stimuli for distractor_1 ; eight stimuli for distractor_2) and overall, I would like to display 128 trials (32 per type of trials). I also would like that, at the block level, each possible pair of stimuli (64 pairs = stim_1 with distractor_1 and 64 pairs = stim_1 with distractor_2) would be displayed only once, with stim_1 being randomly displayed either in the upper part of the screen or either in the lower part of the screen. I have mainly used this post to compute the actual code : https://www.millisecond.com/forums/Topic2273.aspxAny help would be greatly appreciated! Thank you very much, warm regards, S.M By Dave - 9/23/2021 +x SilvioM - 9/23/2021Dear all, I have been working on an Inquisit script (please find it attached) and I am struggling with the stimuli selection. I have a block with four different types of trials: approaching stim_1 in the upper part of the screen with distractor_1; approaching stim_1 in the lower part of the screen with distractor_1; approaching stim_1 in the upper part of the screen with distractor_2; approaching stim_1 in the lower part of the screen with distractor_2. There are eight stimuli by category (ie eight stimuli for stim_1 ; eight stimuli for distractor_1 ; eight stimuli for distractor_2) and overall, I would like to display 128 trials (32 per type of trials). I also would like that, at the block level, each possible pair of stimuli (64 pairs = stim_1 with distractor_1 and 64 pairs = stim_1 with distractor_2) would be displayed only once, with stim_1 being randomly displayed either in the upper part of the screen or either in the lower part of the screen. I have mainly used this post to compute the actual code : https://www.millisecond.com/forums/Topic2273.aspxAny help would be greatly appreciated! Thank you very much, warm regards, S.MWhat are your concrete questions By Dave - 9/23/2021 +x Dave - 9/23/2021+x SilvioM - 9/23/2021Dear all, I have been working on an Inquisit script (please find it attached) and I am struggling with the stimuli selection. I have a block with four different types of trials: approaching stim_1 in the upper part of the screen with distractor_1; approaching stim_1 in the lower part of the screen with distractor_1; approaching stim_1 in the upper part of the screen with distractor_2; approaching stim_1 in the lower part of the screen with distractor_2. There are eight stimuli by category (ie eight stimuli for stim_1 ; eight stimuli for distractor_1 ; eight stimuli for distractor_2) and overall, I would like to display 128 trials (32 per type of trials). I also would like that, at the block level, each possible pair of stimuli (64 pairs = stim_1 with distractor_1 and 64 pairs = stim_1 with distractor_2) would be displayed only once, with stim_1 being randomly displayed either in the upper part of the screen or either in the lower part of the screen. I have mainly used this post to compute the actual code : https://www.millisecond.com/forums/Topic2273.aspxAny help would be greatly appreciated! Thank you very much, warm regards, S.MWhat are your concrete questions> I also would like that, at the block level, each possible pair of stimuli (64 pairs = stim_1 with distractor_1 and 64 pairs = stim_1 with distractor_2) would be displayed only once, with stim_1 being randomly displayed either in the upper part of the screen or either in the lower part of the screen.Then the two trials Approach_PA_SED_top and Approach_PA_SED_bottom should sample from the same set of two counters, not two separate sets of counters.Same for the two trials Approach_PA_NEU_top and Approach_PA_NEU_bottom. By SilvioM - 9/23/2021 My question is: how can I make each pair of stimuli (stim_1 with distractor_1 and stim_1 with distractor_2) appear only once?At the moment, as I pick 32 trials from the first trial condition (ie stim_1 on the top of the screen) and 32 trials from the second trial condition (ie stim_1 on the bottom of the screen), some pairs of trials may be redondant across conditions, and some pairs of trials may not be displayed. I hope that it is clearer now, thank you very much for your support. By Dave - 9/23/2021 +x SilvioM - 9/23/2021My question is: how can I make each pair of stimuli (stim_1 with distractor_1 and stim_1 with distractor_2) appear only once?At the moment, as I pick 32 trials from the first trial condition (ie stim_1 on the top of the screen) and 32 trials from the second trial condition (ie stim_1 on the bottom of the screen), some pairs of trials may be redondant across conditions, and some pairs of trials may not be displayed. I hope that it is clearer now, thank you very much for your support. As I said in my previous response, you ought to have the two NEU trials sample from the same two counters, and same thing for the two SED trials. 64 SED target-distractor combinations/ select = noreplace/ items = (1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8)## I create all combinations for target stimuli/ select = current(counter_Approach_PA_SED_target)/ items = (1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8)and distracting stimuliwith / ontrialbegin = [values.Approach_PA_SED_top = counter.counter_Approach_PA_SED_target.selectedvalue;    values.Avoid_SED_bottom = counter.counter_Avoid_SED_distractor.selectedvalue;    ]/ stimulusframes = [1=focuspoint; 100 = Approach_PA_SED_top, Avoid_SED_bottom, moi]/ validresponse = ("t", "b","g")/ correctresponse = ("t")/ timeout = 10000/ branch = [if (trial.Approach_PA_SED_top.response == 0) trial.tooslowfb]                            / branch = [if (trial.Approach_PA_SED_top.error) trial.errorfb]                                        / branch = [if (trial.Approach_PA_SED_top.correct) trial.correctfb_Approach_PA_SED_top] / ontrialbegin = [values.Approach_PA_SED_top = counter.counter_Approach_PA_SED_target.selectedvalue;    values.Avoid_SED_bottom = counter.counter_Avoid_SED_distractor.selectedvalue;    ]/ stimulusframes = [1=focuspoint; 100 = Approach_PA_SED_top, Avoid_SED_bottom, moi]/ validresponse = ("t", "b","g")/ correctresponse = ("t")/ timeout = 10000/ branch = [if (trial.Approach_PA_SED_top.response == 0) trial.tooslowfb]                            / branch = [if (trial.Approach_PA_SED_top.error) trial.errorfb]                                        / branch = [if (trial.Approach_PA_SED_top.correct) trial.correctfb_Approach_PA_SED_top]