diff --git a/java/res/xml/prefs.xml b/java/res/xml/prefs.xml
index 2ca1af9..d3ac0da 100644
--- a/java/res/xml/prefs.xml
+++ b/java/res/xml/prefs.xml
@@ -117,6 +117,13 @@
             android:persistent="true"
             android:defaultValue="true"
             />
-    </PreferenceCategory>            
+    </PreferenceCategory>
+
+    <CheckBoxPreference
+            android:key="usability_study_mode"
+            android:title="@string/prefs_usability_study_mode"
+            android:persistent="true"
+            android:defaultValue="false"
+            />
 
 </PreferenceScreen>