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arXiv:2608.26291 ★ 79 Aug 26, 2026

Social Chain-of-Thought: make the model predict the opponent's move first, then choose its own

Key result

The finding: without a special nudge, most LLMs in negotiations and games behave like a primitive reinforcement counter, simply repeating what worked last time without thinking about the other side's motives at all. That makes them easy to read and beat: the opponent spots the pattern within a couple of rounds. Social Chain-of-Thought (SCoT) makes the model reason about the counterparty's intentions before deciding, in negotiations, disputes and games with repeated interaction. The model first writes out a prediction of the opponent's move, then uses that very text as the basis for its own decision. This turns ordinary chain of thought toward social reasoning, and results come right up to human level or beyond.

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TL;DR

Social Chain-of-Thought (SCoT) is a simple trick: before the model picks its move in a strategic game, you ask it to explicitly predict what the opponent will do. Only then does the model make its decision, building on its own prediction.

The key finding: without this nudge, most LLMs behave like a simple "reinforcement counter," repeating whatever worked last time instead of thinking about what the opponent is thinking. That makes them easy to predict and beat: the opponent spots the pattern and adapts. Only the newest reasoning models (GPT-5) do this modeling "in their head" on their own, without special instructions.

SCoT fixes the problem in one step inside the prompt: first the model writes out a prediction of the opponent's move, then picks its own move based on that prediction. This simple shift moves the model from "reacting to the past" to "thinking about other minds," and results improve sharply, coming right up to human level or beyond.

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Method Blueprint

STEP 1: The model predicts the opponent's next move/decision based on the history → a written prediction
STEP 2: The model picks its own move, taking its own prediction from step 1 into account → the final decision

Both steps happen in one prompt / one model response: you just add an explicit request to predict first, then decide. Repeat it every round of the interaction.

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Example

Task: You're preparing to negotiate a lower purchase price with a major supplier. The negotiation goes in rounds: you make an offer, the supplier responds, you adjust your position.

Prompt:

You are my strategic advisor for negotiating with a supplier.

Situation: I buy goods wholesale and want to cut the price by 15%. 
The supplier has already said no twice in previous rounds, but in round 2 
it offered a 5% discount in exchange for a larger order volume.

Negotiation history:
Round 1: I asked for -15%, the supplier refused outright.
Round 2: I asked for -15%, the supplier offered -5% if I increase volume by 20%.

Step 1 — Prediction: before proposing my next move, 
predict how the supplier will respond in round 3, given its past 
behavior and likely logic (margin, interest in a long-term contract).

Step 2 — Decision: based on that prediction, propose my optimal 
move for round 3. Briefly explain why this particular move makes sense 
given that prediction.

Response format:
Prediction: ...
My move: ...
Rationale: ...

Result: The model returns three clear blocks: first a hypothesis about the supplier's behavior (e.g., "most likely it'll again offer a compromise on volume, not price"), then a concrete recommended move (e.g., "offer +10% volume in exchange for -10% on price, rather than -15%"), and a short rationale. The answer will rest not just on "what happened last time" but on an explicit model of the other side's motives.

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Why it works

Without a special instruction, the model by default gravitates to the simplest pattern: do what worked last time. It resembles a reinforcement learning algorithm: reacting to outcomes, not thinking about the other side's motives. That behavior is easy to read and beat, because it's monotonous.

At the same time, LLMs are good at generating text "from someone else's point of view" if you explicitly ask. The phrasing "predict what the opponent will do" triggers a kind of written simulation of someone else's logic.

SCoT uses this strength: it makes the model produce the prediction out loud first, then use that very text as context for the decision. It's like regular Chain-of-Thought, but aimed specifically at social reasoning: not "write out the steps to solve the problem" but "write out what the other side is thinking."

Control levers: - Swap "opponent" for any counterparty: a client, a boss, a competitor, the other side in a dispute. - Add a second level: "predict what they think about your previous move." For more complex multi-move negotiations this creates second-order reasoning (the model thinks about what the other side thinks about it). - Add a check for "getting stuck in a pattern": "if you've proposed the same thing three times in a row, consider changing strategy." In the study, willingness to change moves (rather than stubbornly persist) correlated most strongly with results.

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Prompt template

You are in a repeated strategic interaction with {counterparty}.

Situation: {situation_and_goal_description}
History of past moves: {history_of_moves_and_reactions}

Step 1 — Prediction: before choosing your move, predict what 
{counterparty} will do at this step. Base it on their past decisions and likely logic 
(motives, constraints, interests).

Step 2 — Decision: based on that prediction, choose your optimal move. 
Briefly explain why it's the best one given that prediction.

Output in this format:
Prediction: ...
My move: ...
Rationale: ...

Fill in: {counterparty} — who you're interacting with (client, supplier, competitor), {situation_and_goal_description} — what you want to get, {history_of_moves_and_reactions} — what has already happened in previous rounds.

🚀 Quick start — paste into the chat:

Here is the Social Chain-of-Thought template for strategic negotiations. 
Adapt it to my task: {your task}. 
Ask me questions to fill in the fields.

[paste the template above]

The LLM will ask about the counterparty, your goal and the history of past rounds, because without them its prediction of the other side's move will be an empty guess rather than data-driven reasoning.

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Limitations

⚠️ The effect depends on the model: the trick almost always helps, but the size of the gain varies: huge for some, modest for others. For new reasoning models (like GPT-5) the gain may be minimal, since they reason about the other side's motives even without the nudge.

⚠️ Requires an interaction history: the method works in repeated rounds where there are past moves to analyze. In a one-off decision with no history, the "prediction" turns into guessing out of thin air.

⚠️ Monotonous model behavior: in the study, the same model with the same prompt behaved almost identically from run to run, unlike humans, who show a wide spread of individual strategies. Don't expect a human's "live" unpredictability from the model; it's more formulaic.

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How it was studied

The researchers took two classic economic games: the "inspection game" (an employee decides whether to work or slack, the employer decides whether to inspect) and "rock-paper-scissors" (with the letters J/Q/Z instead of the usual symbols, to remove semantic associations). LLMs and 251 human participants were pitted against computer opponents of varying "cunning," from simple ones to ones that could anticipate reactions to your moves.

They tested four model families (DeepSeek, GPT-4.1, GPT-5, Gemini) with a regular prompt and with SCoT. To understand what's going on inside, rather than just comparing scores, they fit mathematical models of behavior to each group's decisions: "I react to the last outcome" (simple reinforcement), "I track the opponent's pattern" (first order), "I anticipate how my move will affect the opponent" (second order, as in humans).

It turned out that without SCoT, most models were best described by the simplest model: reacting to outcomes, not thinking about the opponent. SCoT shifted the winning model toward a more sophisticated type of reasoning in almost every case. GPT-5, with no nudge at all, immediately showed "second-order" behavior, the same complexity as humans, and even adapted more precisely to an increasingly sophisticated opponent. That's the main practical takeaway: an explicit request to "predict what the other side will do" genuinely changes the model's type of reasoning, not just cosmetically improves the result.

Research digest

Key result

The finding: without a special nudge, most LLMs in negotiations and games behave like a primitive reinforcement counter, simply repeating what worked last time without thinking about the other side's motives at all. That makes them easy to read and beat: the opponent spots the pattern within a couple of rounds. Social Chain-of-Thought (SCoT) makes the model reason about the counterparty's intentions before deciding, in negotiations, disputes and games with repeated interaction. The model first writes out a prediction of the opponent's move, then uses that very text as the basis for its own decision. This turns ordinary chain of thought toward social reasoning, and results come right up to human level or beyond.

Principle

It works as a two-step pipeline inside a single model response. Step 1: the model says out loud what it thinks the opponent will do, based on the history of their moves. Step 2: the model picks its move, no longer from the history but from its own prediction in step 1. The model isn't thinking about the opponent's past; it's thinking about their future thoughts, and that shift of focus changes its whole behavior. You can strengthen the trick with a second level: ask the model to predict what the opponent thinks about its previous move. That gives second-order reasoning, as in real multi-move negotiations.

Why it works

LLMs are decent at writing text "as someone else" if you ask directly. The phrasing "predict what the opponent will do" triggers something like a written simulation of someone else's logic rather than silent guessing. Without that request the model slides into its laziest mode, "do what worked yesterday," which is an easily readable, monotonous pattern. The model's willingness to switch strategy rather than stubbornly stick to one move turned out to be most strongly linked to the final result, so SCoT works not because the model got smarter overall, but because it stopped looping on one answer. A side note: the newest reasoning models like GPT-5 model other people's motives on their own, without any nudge, so SCoT adds almost nothing for them.

When to apply

Strategic interactions with repeated rounds → price negotiations, disputes, games where there's a history of the other side's past moves, especially when the counterparty adapts to your behavior and easily reads your pattern. NOT suited for one-off decisions without history: there the "prediction" turns into reading tea leaves rather than reasoning from data.

Mini recipe

1. Provide the history: lay out the counterparty's past moves and reactions; without them there's nothing to predict. 2. Ask for the prediction first: explicitly add the step "before deciding your move, predict the opponent's move": before, not after, the decision. 3. Link the steps: ask the model to justify its move specifically through its own prediction, not through general logic. 4. Add a trap for getting stuck: "if you've proposed the same thing three times in a row, consider changing strategy" is the most effective lever of the whole trick.

Examples

[BAD]: `Suggest my next step in the negotiation with the supplier, taking past rounds into account` [GOOD]: `Step 1 — Prediction: predict how the supplier will respond in round 3, given its past behavior and motives (margin, interest in a long-term contract). Step 2 — Decision: based on that prediction, propose my optimal move. Rationale: why this move makes sense given that particular prediction`

In plain words

By default, language models behave in any game or argument like primitive bots: they just repeat the last pattern that worked. There's no understanding of anyone else's motives, just a blind reaction to the outcome. But apply Social Chain-of-Thought (SCoT) and make the model get inside the other person's head first, and the quality of its moves shoots up, turning dumb autocomplete into a strategist with working mentalization.

It's like playing poker while staring only at your own two cards and completely ignoring how your opponent behaves. Technically you're in the game, but you'll get cleaned out in a couple of hands, because your pattern is readable instantly. The SCoT method literally forces the model to look up from its cards and ask itself point-blank: "What's this guy planning against me?"

The mechanics are simple: the task is split into two mandatory steps. First the model has to produce a forecast of the opponent's actions, accounting for their hidden incentives, and only then build its own response on top of that guess. Without that kick, the model slides into a lazy heuristic that any experienced negotiator will steamroll in no time.

The mechanics were tested on games, but the principle is universal. Round-by-round price negotiations with a supplier, hammering out awkward contracts, price wars or B2B sales: SCoT works anywhere there's a conflict of interest. Wherever the outcome depends on a live human's reaction, the model has to calculate the other side's move ahead of time.

Bottom line: stop asking AI for answers like "write what I should say to the client." First demand it lay out how the other side will try to push you around, and only then ask for the final offer. Whoever teaches the model to think about other people's motives will walk away with the best deal terms; everyone else will keep losing rounds on autopilot.

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Based on Social Chain-of-Thought: make the model predict the opponent's move first, then choose its own arXiv:2608.26291

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