diff --git a/docs/overview/dynamic-parameters.md b/docs/overview/dynamic-parameters.md
index 6ac8b05f..90207a0d 100644
--- a/docs/overview/dynamic-parameters.md
+++ b/docs/overview/dynamic-parameters.md
@@ -32,6 +32,7 @@ var trial = {
 
 var feedback = {
   type: jsPsychHtmlKeyboardResponse,
+  trial_duration: 1000,
   stimulus: function(){
     // The feedback stimulus is a dynamic parameter because we can't know in advance whether
     // the stimulus should be 'correct' or 'incorrect'.