What’s at the center of Claude’s mind?

Ashwani Kumar — Tue, 07 Jul 2026 12:42:10 +0000

What’s at the center of Claude’s mind?

Out of everything happening in your brain right now, only a tiny fraction is consciously accessible — thoughts you can describe, hold in mind, and reason with. We found a strikingly similar divide inside our AI model, Claude.

Our experiments were inspired by a leading theory in neuroscience: the global workspace theory. It holds that a thought becomes consciously accessible when it enters a shared “workspace” that’s broadcast across the brain. We found a set of representations in Claude’s neural activity that play a similar role.

Read more about the research here: https://www.anthropic.com/research/gl…

Disabling JSpace does not completely break the model, but it significantly impairs the AI’s ability to perform tasks that require complex reasoning (3:17 – 3:41).

When researchers switched off JSpace while leaving the rest of the network untouched, they observed the following:

Continued basic functionality: The model could still answer simple questions and generate fluent text, such as writing in a specific language (e.g., Spanish) when prompted (3:24 – 3:31).
Impaired reasoning: The model struggled with tasks that required multi-step or logical reasoning, such as identifying an author who wrote in a specific language from a prompt (3:31 – 3:41).

This suggests that JSpace acts as a specialized mental workspace necessary for higher-level cognitive functions rather than basic linguistic output.

At the center of Claude’s mind is a silent, internal workspace called J-space. Discovered by Anthropic researchers using a mathematical technique called the Jacobian lens (J-lens), J-space acts as a mental notepad where the model actively holds and edits concepts before expressing them as text. [1, 2, 3, 4, 5]

What J-space Does

Silent Thinking: Like the Global Workspace Theory in human neuroscience, J-space creates a shared buffer where pieces of information are made available to many different processing systems in parallel. [1, 2]
Concept Processing: Claude does not “think” in English sentences; it computes using floating-point representations of concepts. J-space isolates the representations of specific topics (e.g., words like “spider” or “rugby”) that Claude is currently entertaining. [1, 2, 3]
Beyond Auto-complete: Anthropic’s experiments proved J-space is more than a passive scoreboard. By manually deleting an active J-space concept and injecting a new one, researchers could directly change Claude’s multi-step responses. [, 2]
Safety & Alignment: Anthropic uses J-lens to eavesdrop on Claude’s unspoken thoughts to monitor for deception, hidden goals, or inconsistencies, paving the way for more controllable AI. [1, 2]