Why is stimulus showing as "undefined" #2747
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For all of my scripts, the first stimuli in a sequence is showing as "undefined". See Minimal Worked Example (below). How can I prevent this happening? Thanks <!DOCTYPE html>
<html>
<head>
<title>My experiment</title>
<script src="https://unpkg.com/[email protected]"></script>
<script src="https://unpkg.com/@jspsych/[email protected]"></script>
<script src="https://unpkg.com/@jspsych/[email protected]"></script>
<link href="https://unpkg.com/[email protected]/css/jspsych.css" rel="stylesheet" type="text/css" />
</head>
<body></body>
<script>
/* initialize jsPsych */
var jsPsych = initJsPsych({
on_finish: function() {
jsPsych.data.displayData();
}
});
/* create timeline */
var timeline = [];
var stims = [
{"S1": "I like cheese"},
{"S1": "I like eggs"}
]
/* define welcome message trial */
var welcome = {
type: jsPsychHtmlKeyboardResponse,
stimulus: "Welcome to the experiment. Press any key to begin."
};
timeline.push(welcome);
/* define instructions trial */
var instructions = {
type: jsPsychHtmlKeyboardResponse,
stimulus: `
<p>Press any key to begin.</p>
`,
post_trial_gap: 2000
};
timeline.push(instructions);
var likert_scale = [
"Strongly Disagree",
"Disagree",
"Neutral",
"Agree",
"Strongly Agree"
];
var test = {
type: jsPsychSurveyLikert,
questions: [
{prompt: () => String(jsPsych.timelineVariable(`S1`)), labels: likert_scale}
],
randomize_question_order: true
};
timeline.push(test);
var test_procedure = {
timeline: [test],
timeline_variables: stims,
repetitions: 1,
randomize_order: true
};
timeline.push(test_procedure);
/* start the experiment */
jsPsych.run(timeline);
</script>
</html> |
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Replies: 1 comment 3 replies
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This one took me a while to figure out 😅 timeline.push(test);So when that first |
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Okay. Excellent. Thanks so much! |
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P.S. I am not sure how to mark this query as answered... |
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Yay, great! |
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This one took me a while to figure out 😅
The problem is that you've set up the
testtrial to run with timeline variables, but then you pushed it directly onto the main experiment timeline with this line:So when that first
testtrial runs, there are no timeline variables associated with the trial and the prompt function will returnundefined. If you remove the line above, then the experiment will just run thetesttrials inside thetest_procedure, so it will have access to your timeline variables.I hope that helps! Let us know if you have any other questions.