Dynamically add trials to a timeline based on user-response

[mrinmayik]

Hello all,

I'm coding an experiment using jsPsych 7.1.2, where I want trials to be added based on a user's response. For instance, if a user selects Study Phase, then I want study trials to be displayed. If they select Test Phase, then test trials should be displayed.

Here is the relevant code (in the interest of full disclosure, this solution is adapted from a response from chatGPT!!):

var get_exp_info = {
    type: jsPsychSurvey,
    timeline: [
            {
                pages: [
                    [
                        {
                            type: 'multi-choice',
                            prompt: 'What phase are you running?',
                            name: 'Exp_Phase',
                            options: ['Study',
                                      'Test'],
                            add_other_option: false
                        },
                        {
                            type: 'multi-choice',
                            prompt: 'Which day are you running?',
                            name: 'Exp_Day',
                            options: ['Day 1',
                                      'Day 2'],
                            add_other_option: false
                        }
                    ]
                ]
            }
        ],
    data: {
            task: 'get_expinfo'
        },
    on_finish: function(data) {
        ExpPhase = data.response.Exp_Phase; // Save the user response to the variable
        ExpDay = data.response.Exp_Day; // Save the user response to the variable

        if ( ExpPhase == 'Study' ) { //ExpInfo.filter({task: "get_expinfo"}).trials[0].response.Exp_Phase
            timeline.push(CallSetup(), endtask, VideoWatching(), endtask, PaintingPreference(), endtask, npat, endtask, SceneCongruency(), endtask, Taboo(), endtask, AutobiographicalInterview())
        }else if ( ExpPhase == 'Test' ){
            //Concatenate the things that happen at both time points
            timeline.push(STARTTEST, temporalorder, selfreport_engagement)
        }

    },
    css_classes: ['privatescreenformatting', 'alignverticalhorizontal', 'promptscreen']
}
//Add these two into the timeline
timeline.push(get_subj_id, get_exp_info)

jsPsych.run(timeline);

This doesn't seem to work. It runs the get_subj_id, and get_exp_info trials, and then the experiment terminates, without any error. Any suggestions on how to fix this?

Thank you,
Mrinmayi

PS: Variables, functions used here (e.g., CallSetup(), endtask, VideoWatching() etc.) have been defined before the code block pasted here.

[mrinmayik]

Using jsPsych.addNodeToEndOfTimeline seems to work (this time not suggested by chatGPT 😆 )!

on_finish: function(data) {
        ExpPhase = data.response.Exp_Phase; // Save the user response to the variable
        ExpDay = data.response.Exp_Day; // Save the user response to the variable

        if ( ExpPhase == 'Study' ) { 
            var study_timeline = {
                timeline: [CallSetup(), endtask, VideoWatching(), endtask, PaintingPreference(), endtask, npat, endtask, SceneCongruency(), endtask, Taboo(), endtask, AutobiographicalInterview()]
            }
            jsPsych.addNodeToEndOfTimeline(study_timeline)
        } else if ( ExpPhase == 'Test' ){
            // Concatenate the things that happen at both time points
            var test_timeline = {
               timeline: [STARTTEST, temporalorder, selfreport_engagement]
            }
            jsPsych.addNodeToEndOfTimeline(test_timeline)
        }
    }

Not sure if this is the best solution, but I thought I'd post it to get feedback!

[mrinmayik]

This solution seems to be working for me. Just a quick note to say that the timelines being passed to jsPsych.addNodeToEndOfTimeline need to initialised beforehand. Otherwise anything trials in which stimuli are displayed using timeline variables (e.g., stimulus: jsPsych.timelineVariable('stimulus')) will throw a "resource not found" error.

So I ended up adding the line:
var study_events = [CallSetup(), endtask, VideoWatching(), endtask, PaintingPreference(), endtask, npat, endtask, SceneCongruency(), endtask, Taboo(), endtask, AutobiographicalInterview()]

before the setting up the get_exp_info variable. And then use:

var study_timeline = {
         timeline: study_events
}

Hope this helps!