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AI tool · Harvard

STRINGS

Tailored real-time interactive narrative & scriptwriting

RoleFull-stack · User research · Product design
Year2024
WithSumedh Hindupur · Mozes Jacobs
CourseHarvard CS 2790R · Elena Glassman

A scriptwriting tool that turns each character’s attributes into sliders, so writers steer AI dialogue directly instead of re-prompting. In a pilot with nine writers, the slider mode was preferred over a chat-style baseline (p < .002).

Overview

01

LLM writing tools lift the floor of creative writing and lower its ceiling. Characters drift out of voice, and changing the tone of a scene means another round of prompt engineering. STRINGS gives authorship back to the writer by exposing the dials the model usually hides.

Instead of re-prompting and hoping, you move a character’s attributes and the next line is written against them, closing the gulf of execution that makes most LLM tools feel uncontrollable.

How it works

02

You set up two characters and a scene. In Mode 2 each character gets sliders for response length, emotional state, dialogue style and relationship, with an editable label at each end (Troubled to Confident, for example). The positions go into the prompt as proportions, and GPT-4, cast as an expert screenwriter, writes one line at a time; any line can be edited before the next. Mode 1, the baseline, hands one prompt to GPT-4o and gets the whole scene back. The app counted every edit, slider move and generation for the study, and exports the finished script as a screenplay PDF.

Steer the scene

Try it

Nora and Jules sort the last boxes in their mother’s empty kitchen. The realtor arrives at noon.

NORA

Is that the last of her things?

JULES

The last box. You don’t have to sign today, you know. We could wait till spring.

Jules Stayed. Kept the house running for two years.
Two attributes, one gesture
Emotional state and dialogue style share a pad, so you move them together, the way an actor would.
See what moved
When a line rewrites, the words that changed light up, so the steering is visible.
Mode 1, for contrast
The study’s baseline: one prompt, the whole scene. To change a line, you change the prompt.

Rebuilt in code from the study app, with an original scene. Every line is pre-written; nothing here calls a model.

System

Architecture
STRINGS · SYSTEMHARVARD · 202401 / THE CONTROLSA voice, on slidersNoraCHARACTER 1EMOTIONAL STATETroubledConfidentDIALOGUE STYLEHesitantAssertiveRELATIONSHIPDistantConnectedLENGTHShortLongEVERY END LABEL IS EDITABLE · ONE PANEL PER CHARACTER02 / ONE LINE AT A TIMEThe sliders become the promptPROMPT, AS WRITTEN72% towards Confident and28% towards Troubled. 80%towards Assertive…GPT-4An expertscreenwriter,one line a callNEXT LINE · NORAI’m ready, Jules. Thequestion is whetheryou are.EDIT THE LINE, MOVE A SLIDER, GO AGAINEDITS, SLIDER MOVES AND GENERATIONS LOGGED FOR THE STUDY · EXPORTS A SCREENPLAY PDF03 / TWO MODESSteer, or ask onceMODE 1 · BASELINEAsk onceone prompt → GPT-4othe whole scene backMODE 2 · STRINGSSteersliders → GPT-4one line at a time, editableSTRINGSHARVARD · 202401 / THE CONTROLSA voice, on slidersNoraCHARACTER 1EMOTIONAL STATETroubledConfidentDIALOGUE STYLEHesitantAssertiveRELATIONSHIPDistantConnectedLENGTHShortLongEVERY END LABEL IS EDITABLE02 / ONE LINE AT A TIMESliders become the promptPROMPT, AS WRITTEN72% towards Confident and28% towards Troubled. 80% towardsAssertive and 20% towards Hesitant…GPT-4An expert screenwriterNEXT LINE · NORAI’m ready, Jules. The question iswhether you are.EDIT THE LINE, MOVE A SLIDER, GO AGAINLOGGED FOR THE STUDY · EXPORTS A SCREENPLAY PDF03 / TWO MODESSteer, or ask onceMODE 1 · BASELINEAsk onceone prompt → GPT-4othe whole scene backMODE 2 · STRINGSSteersliders → GPT-4one line at a time, editable

Study

03

A within-subjects pilot with nine novice writers, all college graduates. Each wrote a two-character scene in both modes, in randomized order, then rated control, consistency, creativity and efficiency.

Result

Pilot
STRINGS · PILOTHINDUPUR, CHIARAVALLOTI, JACOBS01 / THE PILOTNine writers, both modesWITHIN-SUBJECTS · RANDOMIZED ORDERp < .002OVERALL PREFERENCE FOR MODE 2TWO-TAILED t-TESTMode 1 was easier to pick up.02 / WHAT THEY CHOSEThe sliders, for dialogue and controlPREFERRED FOR DIALOGUE5 of 9MODE 23 of 9MODE 1FELT MORE IN CONTROL6 of 9MODE 2ONE SLOT PER WRITERSTRINGS · PILOTHARVARD01 / THE PILOTNine writers, both modesWITHIN-SUBJECTS · RANDOMIZED ORDERp < .002OVERALL PREFERENCE FOR MODE 2TWO-TAILED t-TESTMode 1 was easier to pick up.02 / WHAT THEY CHOSEThe sliders, for dialoguePREFERRED FOR DIALOGUE5 of 9MODE 23 of 9MODE 1FELT MORE IN CONTROL6 of 9MODE 2ONE SLOT PER WRITER

Findings

04

Mode 2 won overall and for writing dialogue, and most writers said it put them in control. The one place Mode 1 came out ahead was how quickly people picked it up, which is the cost of the extra controls.

Since then

05

Strings put a character’s attributes on sliders by writing their positions into the prompt. Research has since moved the same idea inside the model: an ICML 2026 paper builds personality sliders that steer a model’s internal activations at inference time, with no prompt text at all. Strings explored the writer-facing side of that idea, and tested it with writers.

The natural next steps: voice presets saved per character, so a voice holds across scenes; a few candidate lines to choose between; and export to Fountain, the plain-text format screenwriters already use.