The Anchor–Interval Hypothesis:
Measuring Phenomenological Duration via Proper Time

This paper starts from a simple observation: equal clock intervals do not feel equal. Fear stretches time. Flow compresses it. Trauma scrambles it. Psychedelics reshape it. These effects are regular and predictable, not random distortions. The paper argues that they reveal the underlying metric of lived time.

The Anchor–Interval Hypothesis treats temporal experience as the accumulation of a variable experiential density laid over an invariant physical backbone. Anchors are public events that keep everyone aligned. Intervals are the stretches of lived time between them. What changes from moment to moment is the density of experience that fills those intervals. Novelty, attention, arousal, and absorption shift that density in lawful ways. When these variables rise or fall, the lived interval expands or contracts even though the physical interval stays fixed.

The paper shows how this structure can be formalized, how it can be made measurable, and how the resulting metric opens a path toward testing temporal consciousness instead of only describing it.

Across fear, flow, trauma, and psychedelics, equal spans of clock time routinely feel unequal; these "distortions" are robust and graded (Zakay & Block 1997; Eagleman 2009; Wittmann 2011; Droit-Volet 2019). Standard models treat them as errors in duration estimation. We propose the Anchor–Interval Hypothesis (AIH): what standard models call distortions are reinterpreted as systematic variation in the experiential metric of lived time. AIH offers a dual-aspect description linking relativity's invariant proper time (Einstein 1905; Rovelli 2018) to a variable experiential density along the same worldline. Public anchors secure intersubjective coordination; intervals are the lived distances constructed between anchors. Lived duration is modeled as the accumulation of this density over proper time, yielding Perceptual Interval Units (PIUs). We propose that momentary density depends on novelty, attention, arousal, and absorption - constructs known to modulate duration judgments-thus rendering lived time operationalizable without reducing it to clocks. The view complements physics by adding a measurable inner metric consistent with relativistic constraints and reframes "distortions" as lawful metric variation. Falsifiability: if experimentally manipulating attention/novelty fails to shift the estimated density, or if PIUs fail to predict retrospective duration/memory beyond clock time, AIH weakens.

We make decisions, form memories, and anchor our lives inside lived time, not clocks. When the density of experience changes, the felt shape of a day changes with it. Some hours are thick. Some vanish. These patterns influence mood, perception, and behavior. They also reveal how consciousness constructs its own temporal geometry.

If lived duration can be measured in a principled way, we can test claims that were once only descriptive. We can study disorders of temporal experience. We can track how attention, novelty, and arousal shape the sense of a day. And we can build tools that adjust to the user's actual felt time instead of the clock's. The paper argues that temporal experience is not noise around an objective baseline. It is a lawful, measurable dimension of mental life.

• Equal clock intervals do not feel equal
• Public anchors keep temporal order aligned across observers
• Lived time is built from intervals filled with varying experiential density
• Novelty, attention, arousal, and absorption shape that density
• The density integrates over proper time to produce lived duration
• Distortions are not errors but the metric of experience
• The framework is falsifiable through manipulation and prediction
• Lived time becomes measurable without reducing it to clock time