AI Gets a Personality: Steering LLMs with Big Five Traits

New research explores how to precisely control personality in large language models without compromising performance.

A recent paper introduces a method to imbue Large Language Models (LLMs) with specific personalities based on the Big Five Personality Traits. This technique allows for stable trait control by identifying optimal layers within the model, offering new possibilities for personalized AI interactions.

Mark Ellison

By Mark Ellison

November 7, 2025

3 min read

AI Gets a Personality: Steering LLMs with Big Five Traits

Key Facts

  • New research proposes 'Activation-Space Personality Steering' for LLMs.
  • The method uses the Big Five Personality Traits (Openness, Conscientiousness, Extraversion, Agreeableness, Neuroticism).
  • It extracts hidden state activations from transformer layers to identify trait-specific optimal layers.
  • Personality traits occupy a low-rank shared subspace within LLMs.
  • Steering can be achieved without negatively impacting the LLM's fluency or general capabilities.

Why You Care

Ever wish your AI assistant could be a bit more, well, you? Or perhaps more empathetic, or even a little more assertive when needed? A new study reveals how we might soon get exactly that. This creation could fundamentally change how you interact with artificial intelligence, making it far more nuanced and tailored to your preferences. What if your customer service bot understood your frustration on a deeper level?

What Actually Happened

Researchers have unveiled a novel approach to imbue Large Language Models (LLMs) with specific personality traits. This method, called “Activation-Space Personality Steering,” is detailed in a paper titled “Hybrid Layer Selection for Stable Trait Control in LLMs.” The team, including Pranav Bhandari and five other authors, proposes a pipeline that extracts hidden state activations from transformer layers, according to the announcement. They use the Big Five Personality Traits — Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism — as a comprehensive structure to model human personality. This structure is empirically validated, as detailed in the blog post. The process identifies trait-specific optimal layers across different model architectures for injection of these personality elements.

Why This Matters to You

This research bridges a essential gap in controlling LLM behavior during generation. The ability to precisely steer an AI’s personality opens up many practical applications for you. Imagine an educational AI that adapts its teaching style to your learning personality. Or consider a mental health chatbot that exhibits a consistently empathetic and agreeable demeanor. The resulting personality-aligned directions are then operationalized through a flexible steering structure, enabling precise control of trait expression in LLM outputs, the research shows. This means you could have an AI companion that genuinely feels like a consistent personality.

Big Five Personality Traits

TraitDescription
OpennessImaginative, curious, artistic, unconventional
ConscientiousnessOrganized, dutiful, disciplined, achievement-oriented
ExtraversionOutgoing, energetic, sociable, assertive
AgreeablenessCooperative, compassionate, trusting, polite
NeuroticismProne to negative emotions, anxious, easily stressed

For example, if you prefer a direct and task-oriented interaction, your AI could be steered towards higher conscientiousness. If you value a more creative and exploratory conversation, its openness could be enhanced. How might your daily tasks change if your AI perfectly complemented your working style?

The Surprising Finding

One of the most intriguing discoveries from this research is the nature of personality within LLMs. The team revealed that personality traits occupy a low-rank shared subspace. This means these complex psychological constructs are not scattered randomly but are concentrated in specific, smaller dimensions within the model’s internal workings. This finding is quite unexpected. It challenges the assumption that personality might be an emergent, diffuse property across the entire model. Instead, it suggests a more structured and manageable representation. The study finds that these latent structures can be transformed into actionable mechanisms for effective steering. This happens through careful perturbations without impacting the fluency, variance, and general capabilities of the LLM. This is a significant revelation for AI developers. It means personality steering can be achieved without making the AI sound unnatural or less capable.

What Happens Next

This research lays the groundwork for more and personalized AI systems. We can anticipate initial integrations of this system within the next 12 to 18 months, according to the announcement. For example, future virtual assistants could offer selectable personality profiles. You might choose an “optimistic guide” for travel planning or a “calm advisor” for financial decisions. The industry implications are substantial, potentially leading to more engaging customer service bots and highly specialized educational tools. The team revealed that their method helps to bridge the gap between psychological theory and practical model alignment. This suggests a future where AI’s emotional intelligence is as controllable as its factual knowledge. Keep an eye out for initial applications appearing in specialized AI products by late 2026 or early 2027.

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