diff --git a/src/lib/rt-categorize-html.js b/src/lib/rt-categorize-html.js
index 6d71747..aaae3fc 100644
--- a/src/lib/rt-categorize-html.js
+++ b/src/lib/rt-categorize-html.js
@@ -116,24 +116,21 @@ export function rt_categorize_html() {
 
     // create response function
     var after_response = function(info) {
-
       // kill any remaining setTimeout handlers
       jsPsych.pluginAPI.clearAllTimeouts();
 
       // clear keyboard listener
       jsPsych.pluginAPI.cancelAllKeyboardResponses();
 
-      var correct = false;
-      if (trial.key_answer === info.key) {
-        correct = true;
-      }
+      const correct = trial.key_answer === info.key - 96 || trial.key_answer === info.key - 48;
 
       // save data
       trial_data = {
         "rt": info.rt,
         "correct": correct,
         "stimulus": trial.stimulus,
-        "key_press": info.key
+        "key_press": info.key,
+        "key_answer": trial.key_answer
       };
 
       display_element.innerHTML = '';
diff --git a/src/trials/interference.js b/src/trials/interference.js
index 0002cb7..6c484e3 100644
--- a/src/trials/interference.js
+++ b/src/trials/interference.js
@@ -9,21 +9,12 @@ const interference = (trial, experimentConfig) => {
     type: 'rt-categorize-html',
     trial_duration: experimentConfig.response_time_limit,
     on_load: () => pdSpotEncode(code),
-    key_answer: 48+trial.Correct,
+    key_answer: trial.Correct,
     show_stim_with_feedback: false,
     feedback_duration: 2000,
     timeout_message: interferenceTrial(lang.prompt.too_slow, true) + photodiodeGhostBox(),
     stimulus: stimulus,
     response_ends_trial: true,
-    on_finish: (data) => {
-      if (data.key_press !== null) {
-        data.correct = trial.Correct === data.key_press - 48;
-      }
-      else {
-        data.correct = false;
-      }
-      data.code = data.key_press - 48
-    }
   }
 }