Adding Parameters

We first define the parameters:

const defaultParameters = {
    number_of_trials: {
        type: "integer",
        default: 3,
        description: "How many trials to run.",
    },
    number_of_congruent_trials: {
        type: "integer",
        default: 2,
        description: "How many trials will be congruent (word matches its color).",
    },
    fixation_cross_duration_ms: {
        type: "number",
        default: 1000,
        description: "Duration, in milliseconds, of how long the fixation across will be shown.",
    },
    post_fixation_cross_blank_duration_ms: {
        type: "number",
        default: 1000,
        description: "Duration, in milliseconds, of how long a blank screen is shown after the fixation cross is hidden but before the word and response buttons are shown.",
    },
    show_feedback: {
        type: "boolean",
        default: false,
        description: "Should feedback, in the form of the user's performance, be shown at the end of the assessment? Default is true.",
    }
};

Using parameters

We call game.getParameter() to retrieve the value of each parameter and use that in place of a hard-coded value.

This is done in in the randomization code:

const numberOfTrials = game.getParameter("number_of_trials");
const numberOfCongruentTrials = game.getParameter("number_of_congruent_trials");

It is also used in the Actions that show the fixation cross and word:

Action.custom( {callback: () => {
    fixationCross.hidden = false;
}}),
Action.wait({duration: game.getParameter("fixation_cross_duration_ms")}),
Action.custom( {callback: () => {
    fixationCross.hidden = true;
}}),
Action.wait({duration: game.getParameter("post_fixation_cross_blank_duration_ms")}),

Finally, determine whether to show the results on the last scene. To do this, we now initialize the results labels' text to empty strings (""). Only in the end scene's onSetup event handler do we set the labels' text to the results, if show_feedback is true:

endScene.onSetup( ()=> {
    if (game.getParameter("show_feedback")) {
        const percentCorrect = game.data.trials.filter((trial) => trial.response_correct).length / numberOfTrials;
        percentCorrectLabel.text = "Percent correct: " + percentCorrect.toFixed(2);

        const congruentTrials = game.data.trials.filter((trial) => trial.congruent_stimulus);
        let congruentRtSum = 0;
        for (let i = 0; i < congruentTrials.length; i++) {
            congruentRtSum = congruentRtSum + congruentTrials[i].response_time_ms;
        }
        const meanCongruentRt = congruentRtSum / congruentTrials.length;
        congruentRtLabel.text = "Mean congruent rt: " + meanCongruentRt.toFixed(2);

        const incongruentTrials = game.data.trials.filter((trial) => !trial.congruent_stimulus);
        let incongruentRtSum = 0;
        for (let i = 0; i < incongruentTrials.length; i++) {
            incongruentRtSum = incongruentRtSum + incongruentTrials[i].response_time_ms;
        }
        const meanIncongruentRt = incongruentRtSum / incongruentTrials.length;
        incongruentRtLabel.text = "Mean incongruent rt: " + meanIncongruentRt.toFixed(2);
    }
});

Progress so far

You now have a fully completed assessment with parameters. The next page will present this at full size.

Run

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