diff --git a/components/boundingNew.js b/components/boundingNew.js
index ea671538..48c4d62f 100644
--- a/components/boundingNew.js
+++ b/components/boundingNew.js
@@ -324,6 +324,7 @@ export const restrictLevelBeforeFixation = (
   fontCharacterSet,
   spacingDirection = "horizontal",
   targetSizeIsHeightBool = false,
+  letterCharacters,
 ) => {
   const quickCase = getQuickCase(
     targetTask,
@@ -347,10 +348,20 @@ export const restrictLevelBeforeFixation = (
     targetString = sampleWithoutReplacement(fontCharacterSet, 1)[0];
     characterSet = targetString;
   } else if (quickCase === "typographicCrowding") {
-    [targetString, flanker1String, flanker2String] = sampleWithoutReplacement(
-      fontCharacterSet,
-      3,
-    );
+    const { target, flanker1, flanker2 } = letterCharacters ?? {};
+    const selectedCharacters = [target, flanker1, flanker2];
+    if (
+      selectedCharacters.some(
+        (character) => typeof character !== "string" || character.length === 0,
+      )
+    ) {
+      throw new Error(
+        "Typographic crowding requires a selected target and two flankers.",
+      );
+    }
+    targetString = target;
+    flanker1String = flanker1;
+    flanker2String = flanker2;
     characterSet = [flanker1String, targetString, flanker2String];
   } else if (quickCase === "ratioCrowding") {
     switch (spacingDirection) {
diff --git a/components/stimulusGeneration.ts b/components/stimulusGeneration.ts
index 013f416c..e50fa44e 100644
--- a/components/stimulusGeneration.ts
+++ b/components/stimulusGeneration.ts
@@ -28,6 +28,7 @@ import type {
   RsvpReadingStimulusResults,
   VernierStimulusResults,
   TextStimsLetter,
+  CharactersLetter,
 } from "./stimulus";
 import { rc, viewingDistanceCm } from "./global";
 import { Screens } from "./multiple-displays/globals";
@@ -127,7 +128,7 @@ const getLettersStimulus = (
         reader,
         extraInfo.characterSetBoundingRect,
         extraInfo.stage as PartOfTrial,
-        extraInfo.characters.target,
+        extraInfo.characters,
         extraInfo.proposedLevel,
       ));
   }
@@ -272,13 +273,14 @@ const getLettersStimulusV2 = (
   reader: ParamReader,
   characterSetBoundingRectOld: any,
   stage: PartOfTrial,
-  targetCharacter?: string,
+  letterCharacters: CharactersLetter,
   proposedLevel?: number,
 ): {
   level: number;
   stimulusParameters: any;
   characterSetBoundingRect: any;
 } => {
+  const targetCharacter = letterCharacters.target;
   if (stage === "afterFixation" && !(targetCharacter && proposedLevel)) {
     throw new Error(
       `targetCharacter (${targetCharacter}) and proposedLevel (${proposedLevel}) must be provided for afterFixation letter stimulus generation.`,
@@ -304,6 +306,7 @@ const getLettersStimulusV2 = (
       String(reader.read("fontCharacterSet", block_condition)).split(""),
       reader.read("spacingDirection", block_condition),
       reader.read("targetSizeIsHeightBool", block_condition),
+      letterCharacters,
     );
   } else if (stage === "afterFixation") {
     [level, stimulusParameters] = restrictLevelAfterFixation(