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Synthetic Personalities
The NeoThymos primer on Synthetic Personalities - Symbolically defined personas, grounded in human psychology and portable across many of the frameworks that our agents run on today.
NeoThymos is a tool used to define, synthesize, store and manage the deployment of Synthetic Personalities.
The initial version of NeoThymos is intended for developers of agentic systems. It can also be used by any creative storyteller looking for a more formal way to represent character personality. Future versions will be tailored to the specific needs of storytellers and other creative developers but it can be used today where a character study of a precisely engineered personality would be a useful work product.
Continue reading to learn more about what this means, why it is important, and how these concepts inform and support developers working with today’s agent runtime environments and agentic frameworks.
- … Grounded, Synthetic and Portable*
NeoThymos personalities are Grounded, Synthetic and Portable. In this article we’ll introduce each of these terms and how they relate to one another, providing jumping off points where you can delve more deeply, exploring related concepts and topics or learn about the psychological theories, models and designs that support our work.
We’ll conclude by briefly identifying other domains where such synthetic personalities may soon be used and then take a look at the deeper architecture and design features of NT Personalities, why they exist and where they will lead us in the future.
What do we mean by Personality?
Our primary focus is to characterize human personality types, independent of whether they belong to an actual person or are worn by a synthetic, neuro-symbolic entity - an AI agent. We all have a general idea of what personality means but let’s take a closer look at how psychologists talk about it and along the way point out how personality differs from, and relates to, adjacent concepts.
First though we want to be up front about one thing. There are differing opinions concerning whether or not it is appropriate to anthropomorphize machines in this way. We won’t get into those debates in this article except to note that there are reasonable arguments on both sides. The topic is discussed in greater depth in “Should we anthropomorphize our machines?”.
Formally, in scientific psychology, personality is fundamentally about internal structure, stability, and measurable variance between individuals. The American Psychological Association currently defines it as - “the enduring configuration of characteristics and behavior that comprise an individual’s unique adjustment to life.”
Gordon Allport (1897–1967) was an American psychologist and one of the founders of modern personality psychology.
Personality - “The dynamic organization within the individual of those psychophysical systems that determine his(/her) characteristic behavior and thought.”
He is particularly important because he helped shift psychology away from treating personality as a collection of isolated behaviors and toward understanding it as an organized, enduring system of individual characteristics.
He described personality as: “The dynamic organization within the individual of those psychophysical systems that determine his characteristic behavior and thought.” We will adopt his definition here.
When we talk about a personality, we think about it as a generally stable, abstract, internal mental state that influences the outward behavior of an agent; whether that agent be a flesh and blood human being, a synthetic machine intelligence, a creatively authored storybook character or a humanoid robot.
To make things even clearer we need to separate the concepts of identity and personality. Identity consists of the concrete attributes of an entity such as name, sex, age, hair color, while personality contains abstract characteristics like sentimentality, sociability, flexibility and diligence.
Persona = Identity + Personality
Being clear on the terminology we use makes it much easier to talk about the psychology of personality and how it is modeled and used in the NeoThymos system. When we bind together a personality and an identity we use the term Persona to describe this pairing. Persona = Identity + Personality. Each time we combine the concrete elements of an Identity with the more abstract structure of a specific personality we create a unique persona.
Note that some agentic frameworks like Open Claw support this distinction explicitly ( IDENTITY.md & SOUL.md files). In such cases NeoThymos maps directly onto these file structures when it renders a persona for the developer to use.
Personality is what a character is like… Identity is who they are
Another way to understand this distinction is the swap test: if you swap out the identity of a persona for another identity you will get an agent that acts the same but may “look” very different. But, if you keep the identity and swap out the personality you get an agent that looks the same but whose behavior can be quite different. Personality is what a character is like (an inquisitive, socially bold, perfectionist). Identity is who they are (a 32 year old female named Alice).
In NeoThymos, we often use the term core personality to describe the structure of an abstract personality, independent of the concrete aspects of a persona which we simply refer to as identity .
Finally, be aware that the terms NT Personality and NT Persona Kit are often used somewhat interchangeably as a generalized shorthand for the full collection of content rendered by NeoThymos and delivered to the developer as a kit of files that contain information generated from not only the full persona (core personality + identity) but also the fine tuned communication style and a deployment configuration that is specific to the target deployment environment.
“Grounded”
Psychological Grounding
It is common today for agentic personality to be approached in an ad hoc, almost arbitrary way. Snippets of text excavated from social media and blog posts or handed down from tutorials and example worksheets are cobbled together, deemed “good enough” and stuffed into the context window.
We need a better way, an approach that is defensible, not arbitrary.
The development of agentic AI systems with persistent, expressive personalities, systems that convincingly imitate human behavior, requires application of the psychological foundations that drive human behavior, decision-making, and social interaction.
Fully integrated systems wishing to faithfully emulate the complexity of human activity will need to draw on complementary psychological models that together provide a comprehensive framework for understanding the cognitive, emotional, and moral dimensions of human behavior. Within NeoThymos we draw on four major areas of psychological theory; cognitive appraisal theory for emotional responses, emotional state theory for affective modeling, personality psychology for individual differences, and evolutionary approaches to moral cognition.
Well established psychological models provide the scientific grounding we need to move forward with confidence. Today, NeoThymos leans most heavily on the HEXACO model of personality which is the main surface users of the system see and interact with, but models from the other areas of psychology noted above are also used internally and will play an increasingly important role in future development.
In summary - to create AI agents that are expected to navigate complex social environments and exhibit authentic, contextually appropriate responses, we must draw upon established psychological theories to capture the multifaceted nature of human psychology.
“Synthetic”
Synthetic Personalities
In the study of human psychology the “nurture vs. nature” debate continues to explore where we get our personalities from but there is no question that personality is a natural part of what being human is all about.
Psychometric research has resulted in strong analytical models of human personality, emotion and morality. In NeoThymos we use these models as structural blueprints to construct synthetic personalities.
A synthetic personality is a personality that does not belong to any person but rather is constructed from an engineered model of human behavior that is based on modern theories of human psychology.
Modern LLMs are incredibly skilled at generating text that appears personal and emotional. They have learned the patterns of human expression from vast amounts of training data. If you use exclamation points and words charged with emotional meaning, an LLM will reflect that tone back to you. However, this is a reactive, surface-level effect. It’s a masterful performance, but the actor has no memory of the character’s backstory once the scene ends. NeoThymos, capabilities are complementary to LLMs rather than competing with them.
A neuro-symbolic architecture
The core architectural framing of NeoThymos is as a hybrid system that deliberately blends Good Old-Fashioned AI (GOFAI) with a contemporary Large Language Model (LLM). This design represents a sophisticated separation of concerns: NeoThymos itself acts as a deterministic, rule-like system - managing personality structure and deterministically interpreting personality state. It delegates the stochastic tasks of narrative and image generation to an LLM.
NeoThymos uses a granular version of the HEXACO model of personality to represent the core structure of each synthetic personality. The HEXACO model contains six primary domains of personality each composed of four distinct facets plus one facet that is tied to multiple domains.
Unique and useful synthetic personalities can be synthesized by working with just the 6 domains plus the one interstitial facet. Giving a designer 6 broad “dials” is good, but giving them 25 (one for each facet) is vastly more expressive and engaging. It transforms the “personality knob” into a “personality mixing board” that provides the creative designer the control and fidelity needed to design compelling, unique agent personas.
With this level of control designers can create an agent who is high in Emotionality overall, but specify that this manifests as high Sentimentality (forms strong attachments) but low Fearfulness (is brave). The 6-domain model would struggle to represent this “sentimental hero” archetype, but a 25 dimension core personality makes it intuitive.
Why it’s important
NeoThymos uses deterministic methods to project the core personality vector onto the meaning that is encapsulated in the personality model. It does the same for other psychological models inside the system. Only at the end of this process are LLMs used to generate prose for both humans (e.g. the Character Study) and for agent configuration (e.g. SOUL.md, CLAUDE.md). The process is transparent and reproducible. It is “transparent” unlike the output from an LLM that has accumulated some context but drifts as input and context change.
“Portable”
(Incomplete section - needs work)
A synthetic personality has a home in your account on NeoThymos. From there it can be “Deployed* to multiples AI agent runtime environments. It produces files need to configure the same personality one one or many Environments. Even use for other creative uses.
Agents and other domains
NeoThymos is a tool for creating synthetic personalities. Used as the heart of character personas these Those personalities can be used anywhere characters It’s currently represent and mimic a human personality for use in domains such as; AI agent design & configuration, literary story telling, video/cinematic story telling, video game NPG design, table game design & implementation and embodied AI agents (humanoid and toy robots).
Future Direction
(Incomplete section - needs work)
Today’s NT Personalities are engineered vectors deterministically interpreted within the context of pre-defined models grounded in human psychology.
They do not currently include emotion generating appraisal mechanics, dynamic emotional state management, emotional memory, or recall.
These are the features that will support dynamic, transparent emotional and moral reasoning. Ultimately, this leads to synthetic personalities that evolve over time—not through the black-box emergence of a language model, but in psychologically grounded, realistic, and transparent ways based on events that provoke emotional responses.
Further Reading: The blog carries dispatches from the NeoThymos workshop, you can master basic terminology here and from there explore the glossary where the complete vocabulary lives.