RE: Change duration of a trial depending on participant response.

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RE: Change duration of a trial depending on participant response.

Change duration of a trial depending on participant response.

Author	Message
kev_dent	kev_dent posted 2 Years Ago HOT Topic Details Share Topic
Group: Forum Members Posts: 47, Visits: 153	Hi, I would like to create an experiment where participants view images. I would like to be able to have a participant increase or decrease the amount of time the stimulus is shown to them for by pressing keys. Press one key to increase the stimulus duration, press another key to decrease it. What would be the best way to implement this with inquisit? Thanks Kevin
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Dave	Dave posted 2 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 13K, Visits: 105K	+x kev_dent - 12/6/2023 Hi, I would like to create an experiment where participants view images. I would like to be able to have a participant increase or decrease the amount of time the stimulus is shown to them for by pressing keys. Press one key to increase the stimulus duration, press another key to decrease it. What would be the best way to implement this with inquisit? Thanks Kevin You want that for the currently running trial (i.e, the image is already on-screen) or you want that sometime before any image(s) are displayed? Give a concrete example.
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kev_dent	kev_dent posted 2 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 47, Visits: 153	Ok sure here is some toy code to illustrate what I want to do. Default duration of the stimulus is 4000ms if the participant presses z every press of z adds 100 ms on to this time. If the participant presses n every press of n increases the stimulus duration by 100 milliseconds. The keypresses should occur whilst the stimulus is on the screen. The sequence of keypresses and their timing relative to the start of the trial should also be recorded. Thanks Kevin <trial t> / stimulustimes = [0=t] / beginresponsetime = 0 / inputdevice = keyboard / validresponse = (44,49) / responseinterrupt = trial / isvalidresponse = [ if(trial.t.response == 44) {trial.t.trialduration = trial.t.trialduration + 100; false} else if (trial.t.response == 49) {trial.t.trialduration = trial.t.trialduration + 100;false} ] /trialduration = 4000 </trial> <text t> /items =("X") / erase = false </text>
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kev_dent	kev_dent posted 2 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 47, Visits: 153	Let me try that again. Default duration of the stimulus is 4000ms if the participant presses z every press of z adds 100 ms on to this time. If the participant presses n every press of n decreases the stimulus duration by 100 milliseconds. The keypresses should occur whilst the stimulus is on the screen. The sequence of keypresses and their timing relative to the start of the trial should also be recorded. Thanks Kevin <trial t> / stimulustimes = [0=t] / beginresponsetime = 0 / inputdevice = keyboard / validresponse = (44,49) / responseinterrupt = trial / isvalidresponse = [ if(trial.t.response == 44) {trial.t.trialduration = trial.t.trialduration + 100; false} else if (trial.t.response == 49) {trial.t.trialduration = trial.t.trialduration - 100;false} ] /trialduration = 4000 </trial> <text t> /items =("X") / erase = false </text>
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Dave	Dave posted 2 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 13K, Visits: 105K	+x kev_dent - 12/6/2023 Let me try that again. Default duration of the stimulus is 4000ms if the participant presses z every press of z adds 100 ms on to this time. If the participant presses n every press of n decreases the stimulus duration by 100 milliseconds. The keypresses should occur whilst the stimulus is on the screen. The sequence of keypresses and their timing relative to the start of the trial should also be recorded. Thanks Kevin <trial t> / stimulustimes = [0=t] / beginresponsetime = 0 / inputdevice = keyboard / validresponse = (44,49) / responseinterrupt = trial / isvalidresponse = [ if(trial.t.response == 44) {trial.t.trialduration = trial.t.trialduration + 100; false} else if (trial.t.response == 49) {trial.t.trialduration = trial.t.trialduration - 100;false} ] /trialduration = 4000 </trial> <text t> /items =("X") / erase = false </text> Actually, scratch what I posted previously. It won't work reliably that way. The fundamental problem is that a trial's duration really isn't meant to be changed once it's underway, for obvious performance and timing reasons. So, back to the drawing board. Not sure this can be done, or done well, i.e. without incurring serious timing hiccups
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Dave	Dave posted 2 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 13K, Visits: 105K	+x Dave - 12/6/2023 +x kev_dent - 12/6/2023 Let me try that again. Default duration of the stimulus is 4000ms if the participant presses z every press of z adds 100 ms on to this time. If the participant presses n every press of n decreases the stimulus duration by 100 milliseconds. The keypresses should occur whilst the stimulus is on the screen. The sequence of keypresses and their timing relative to the start of the trial should also be recorded. Thanks Kevin <trial t> / stimulustimes = [0=t] / beginresponsetime = 0 / inputdevice = keyboard / validresponse = (44,49) / responseinterrupt = trial / isvalidresponse = [ if(trial.t.response == 44) {trial.t.trialduration = trial.t.trialduration + 100; false} else if (trial.t.response == 49) {trial.t.trialduration = trial.t.trialduration - 100;false} ] /trialduration = 4000 </trial> <text t> /items =("X") / erase = false </text> Actually, scratch what I posted previously. It won't work reliably that way. The fundamental problem is that a trial's duration really isn't meant to be changed once it's underway, for obvious performance and timing reasons. So, back to the drawing board. Not sure this can be done, or done well, i.e. without incurring serious timing hiccups Alright, the following should work reasonably well: <values> / tduration = 0 / up_responses = 0 / down_responses = 0 / latency = 0 / stimonset = null / timeleft = 0 </values> <block myblock> / trials = [1-4 = trial.t] </block> <trial t> / ontrialbegin = [ values.tduration = 4000; // set default duration values.up_responses = 0; // count up responses in current trial values.down_responses = 0; // count down responses values.latency = 0; values.timeleft = 0; ] / ontrialend = [ values.stimonset = text.t.timestamp; // store stimulus timestamp ] / stimulustimes = [0=clearscreen, t] / validresponse = (0) / trialduration = 0 / branch = [ return trial.t_adjust; ] </trial> <trial t_adjust> / ontrialbegin = [ values.timeleft = values.tduration - values.latency; ] / ontrialend = [ values.latency = script.elapsedtime - values.stimonset; // calculate latency relative to stimulus onset if (trial.t_adjust.response == 44) { // up response values.tduration += 100; values.up_responses += 1; } else if (trial.t_adjust.response ==49) { // down response values.tduration -= 100; values.down_responses += 1; }; ] / validresponse = (44, 49) / beginresponsetime = -1 / timeout = values.timeleft / branch = [ if (trial.t_adjust.response == 0) { return trial.iti; } else { return trial.t_adjust; }; ] </trial> <trial iti> / stimulustimes = [0=clearscreen] / trialduration = 500 / validresponse = (0) / recorddata = false </trial> <text t> / items = ("T") / erase = false </text> <data> / columns = (date time subject group session blocknum blockcode trialnum trialcode response responsetext latency values.tduration values.up_responses values.down_responses values.latency values.timeleft) </data>
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kev_dent	kev_dent posted 2 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 47, Visits: 153	Thanks for your help Dave. I will have a play with this code.
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