diff --git a/task-launcher/serve/serve.js b/task-launcher/serve/serve.js
index e54291b6..87bb9e11 100644
--- a/task-launcher/serve/serve.js
+++ b/task-launcher/serve/serve.js
@@ -61,6 +61,7 @@ const sequentialStimulus = stringToBoolean(urlParams.get('sequentialStimulus'),
 const storeItemId = stringToBoolean(urlParams.get('storeItemId'), false);
 const cat = stringToBoolean(urlParams.get('cat'), false);
 const heavyInstructions = stringToBoolean(urlParams.get('heavyInstructions'), false);
+const debug = stringToBoolean(urlParams.get('debug'), false);
 
 const emulatorConfig = EMULATORS ? firebaseJSON.emulators : undefined;
 // if running in demo mode, no data will be saved to Firestore
@@ -104,6 +105,7 @@ async function startWebApp() {
         heavyInstructions,
         demoMode,
         version,
+        debug,
       };
 
       const taskInfo = {
diff --git a/task-launcher/src/styles/layout/_containers.scss b/task-launcher/src/styles/layout/_containers.scss
index 6e805006..b24ee9ba 100644
--- a/task-launcher/src/styles/layout/_containers.scss
+++ b/task-launcher/src/styles/layout/_containers.scss
@@ -310,3 +310,21 @@
   align-items: center;
   gap: 30px;
 }
+
+.theta-estimate-container {
+  position: absolute;
+  top: 30px;
+  left: 30px;
+  flex-direction: column;
+  justify-content: center;
+  align-items: center;
+  width: 30%;
+  max-height: 50%;
+  border: 1px solid red;
+  border-radius: 10px;
+  background-color: $bg-bubble-base;
+  color: black;
+  font-size: 1.5rem;
+  font-weight: $font-weight-bold;
+  padding: 10px;
+}
diff --git a/task-launcher/src/taskStore/index.ts b/task-launcher/src/taskStore/index.ts
index 6a5d1a55..7250ff39 100644
--- a/task-launcher/src/taskStore/index.ts
+++ b/task-launcher/src/taskStore/index.ts
@@ -26,6 +26,7 @@ import { InputCapability } from '../utils/detectInput';
  * @property {boolean} taskComplete - Whether the task has ended - if true, the user should return to dashboard.
  * @property {Object} assetsPerTask - Object containing list of assets belonging to each task.
  * @property {boolean} demoMode - Whether the task is running in demo mode (no interaction with Firestore), default is false.
+ * @property {boolean} debug - Shows theta estimate on the screen for cat debugging when enabled.
  * @property {number} currentCatBlock - The current block number to select trials from in a CAT.
  * @property {number[]} blockThresholds - Array of theta thresholds.
  * @property {number} totalTrialCount - Total number of trials, including practice and instructions.
@@ -91,6 +92,7 @@ export type TaskStoreDataType = {
   language?: string;
   maxTime?: number;
   demoMode: boolean;
+  debug: boolean;
   version: number;
   currentCatBlock?: number;
   blockThresholds?: number[];
@@ -147,6 +149,7 @@ export const setTaskStore = (config: TaskStoreDataType) => {
     testPhase: false,
     maxTime: config.maxTime,
     demoMode: config.demoMode,
+    debug: config.debug,
     version: config.version || 1,
     currentStoryGroup: 0,
   });
diff --git a/task-launcher/src/tasks/same-different-selection/trials/afcMatch.ts b/task-launcher/src/tasks/same-different-selection/trials/afcMatch.ts
index 12211e6a..092aef26 100644
--- a/task-launcher/src/tasks/same-different-selection/trials/afcMatch.ts
+++ b/task-launcher/src/tasks/same-different-selection/trials/afcMatch.ts
@@ -17,6 +17,7 @@ import { finishExperiment } from '../../shared/trials';
 import { taskStore } from '../../../taskStore';
 import { updateTheta } from '../../shared/helpers';
 import { sdsProgressComponentFilled, sdsProgressComponentEmpty } from '../../shared/helpers/components';
+import { displayDebugInfo } from '../../shared/helpers/displayDebugInfo';
 
 let selectedCards: string[] = [];
 let selectedCardIdxs: number[] = [];
@@ -333,6 +334,8 @@ export const afcMatch = (trial?: StimulusType) => {
           }),
         );
       }
+
+      displayDebugInfo(stim);
     },
     response_ends_trial: () => {
       return (trial || taskStore().nextStimulus).trialType === 'instructions' && taskStore().version === 2;
diff --git a/task-launcher/src/tasks/same-different-selection/trials/legacyStimulus.ts b/task-launcher/src/tasks/same-different-selection/trials/legacyStimulus.ts
index 779ae6a7..30e131db 100644
--- a/task-launcher/src/tasks/same-different-selection/trials/legacyStimulus.ts
+++ b/task-launcher/src/tasks/same-different-selection/trials/legacyStimulus.ts
@@ -15,6 +15,7 @@ import { isTouchScreen, jsPsych } from '../../taskSetup';
 import { taskStore } from '../../../taskStore';
 import { handleStaggeredButtons } from '../../shared/helpers/staggerButtons';
 import { updateTheta } from '../../shared/helpers';
+import { displayDebugInfo } from '../../shared/helpers/displayDebugInfo';
 
 const replayButtonHtmlId = 'replay-btn-revisited';
 let incorrectPracticeResponses: string[] = [];
@@ -249,6 +250,8 @@ export const legacyStimulus = (trial?: StimulusType) => {
           });
         });
       }
+
+      displayDebugInfo(stimulus);
     },
     on_finish: (data: any) => {
       const stim = trial || taskStore().nextStimulus;
diff --git a/task-launcher/src/tasks/same-different-selection/trials/stimulus.ts b/task-launcher/src/tasks/same-different-selection/trials/stimulus.ts
index 546b2f6b..9c1d0a49 100644
--- a/task-launcher/src/tasks/same-different-selection/trials/stimulus.ts
+++ b/task-launcher/src/tasks/same-different-selection/trials/stimulus.ts
@@ -16,6 +16,7 @@ import { isTouchScreen, jsPsych } from '../../taskSetup';
 import { taskStore } from '../../../taskStore';
 import { updateTheta } from '../../shared/helpers';
 import { shouldTerminateCat } from '../../shared/helpers/shouldTerminateCat';
+import { displayDebugInfo } from '../../shared/helpers/displayDebugInfo';
 
 const replayButtonHtmlId = 'replay-btn-revisited';
 let incorrectPracticeResponses: string[] = [];
@@ -401,6 +402,8 @@ export const stimulus = (trial?: StimulusType) => {
           });
         });
       }
+
+      displayDebugInfo(stimulus);
     },
     on_finish: (data: any) => {
       PageAudioHandler.stopAndDisconnectNode();
diff --git a/task-launcher/src/tasks/shared/helpers/config.ts b/task-launcher/src/tasks/shared/helpers/config.ts
index 48e040aa..6d9d5b96 100644
--- a/task-launcher/src/tasks/shared/helpers/config.ts
+++ b/task-launcher/src/tasks/shared/helpers/config.ts
@@ -94,6 +94,7 @@ export const setSharedConfig = async (
     semThreshold,
     startingTheta,
     demoMode,
+    debug,
     version,
     taskVersion, // deprecated; use `version` — kept for backward compatibility
   } = cleanParams;
@@ -127,6 +128,7 @@ export const setSharedConfig = async (
     semThreshold: Number(semThreshold),
     startingTheta: Number(startingTheta),
     demoMode: !!demoMode,
+    debug: !!debug,
     version: Number((version ?? taskVersion) || 1),
     displayPromptDurations: {},
   };
diff --git a/task-launcher/src/tasks/shared/helpers/displayDebugInfo.ts b/task-launcher/src/tasks/shared/helpers/displayDebugInfo.ts
new file mode 100644
index 00000000..7eba5c77
--- /dev/null
+++ b/task-launcher/src/tasks/shared/helpers/displayDebugInfo.ts
@@ -0,0 +1,34 @@
+import { taskStore } from "../../../taskStore";
+import { jsPsych, cat } from "../../taskSetup";
+
+function isRealTrial(trial: any) {
+    return (
+        trial.assessment_stage &&
+        trial.assessment_stage !== 'practice_response' && 
+        trial.assessment_stage !== 'instructions'
+    );
+}
+
+export function displayDebugInfo(stim: StimulusType) {
+    if (taskStore().debug && taskStore().runCat) {
+        const lastRealTrial = jsPsych.data.get().filterCustom(isRealTrial).last().values()[0];
+        const thetaEstimate = cat.theta;
+        const currentTrialDifficulty = stim.difficulty;
+        const CurrentTrialUid = stim.itemUid;
+
+        let previousResponse = 'N/A';
+        if (lastRealTrial?.correct !== undefined) {
+            previousResponse = lastRealTrial.correct ? 'Correct' : 'Incorrect';
+        }
+
+        const thetaEstimateContainer = document.createElement('div');
+        thetaEstimateContainer.classList.add('theta-estimate-container');
+        thetaEstimateContainer.innerHTML = `
+          <p>Theta estimate: ${thetaEstimate}</p>
+          <p>Previous response: ${previousResponse}</p>
+          <p>Current trial difficulty: ${currentTrialDifficulty}</p>
+          <p>Current trial UID: ${CurrentTrialUid}</p>
+        `;
+        document.body.appendChild(thetaEstimateContainer);
+      }    
+};
diff --git a/task-launcher/src/tasks/shared/trials/afcStimulus.ts b/task-launcher/src/tasks/shared/trials/afcStimulus.ts
index 6de17e52..49a6ef78 100644
--- a/task-launcher/src/tasks/shared/trials/afcStimulus.ts
+++ b/task-launcher/src/tasks/shared/trials/afcStimulus.ts
@@ -1,7 +1,7 @@
 // For all tasks except: H&F, Memory Game, Same Different Selection
 import jsPsychHtmlMultiResponse from '@jspsych-contrib/plugin-html-multi-response';
 import _toNumber from 'lodash/toNumber';
-import { jsPsych, isTouchScreen } from '../../taskSetup';
+import { jsPsych, isTouchScreen, cat } from '../../taskSetup';
 import {
   arrowKeyEmojis,
   replayButtonSvg,
@@ -21,6 +21,7 @@ import {
 import { mediaAssets } from '../../..';
 import { finishExperiment } from '.';
 import { taskStore } from '../../../taskStore';
+import { displayDebugInfo } from '../helpers/displayDebugInfo';
 
 const replayButtonHtmlId = 'replay-btn-revisited';
 // Previously chosen responses for current practice trial
@@ -291,6 +292,9 @@ function doOnLoad(layoutConfigMap: Record<string, LayoutConfigType>, trial?: Sti
   }
 
   setupReplayAudio(pageStateHandler);
+
+  // display debug info if enabled
+  displayDebugInfo(stim);
 }
 
 function doOnFinish(
@@ -302,6 +306,10 @@ function doOnFinish(
 ) {
   PageAudioHandler.stopAndDisconnectNode();
 
+  if (taskStore().debug) {
+    document.body.removeChild(document.querySelector('.theta-estimate-container') as Node);
+  }
+
   // note: nextStimulus is actually the current stimulus
   const stimulus = trial || taskStore().nextStimulus;
   const itemLayoutConfig = layoutConfigMap?.[stimulus.itemId];