キキ ネコロゴ

Data Sources & Research Materials

This page provides a detailed explanation of "Janet's Law," the theoretical foundation for the time calculations used in our service "KIKI NEKO," and introduces related research materials and references.

What is Janet's Law

Psychological Mechanism of Time Perception

Definition of the Law

Janet's Law is an empirical rule stating that "the subjective length of time perceived in any period of life is proportional to the reciprocal of age (inversely proportional to age)." It explains the psychological phenomenon where the same objective time feels shorter as one ages.

Mathematical Expression

The subjective time length T at any period of life is proportional to the reciprocal of age A:

T ∝ 1/A

For example, one year for a 50-year-old corresponds to 1/50 of their life, while for a 5-year-old it corresponds to 1/5, so the same year feels shorter to the older person.

Originators and Historical Background

Paul Janet (1823–1899)

A 19th-century French philosopher who suggested the original idea of this law in his 1877 paper.

Paul Janet, "Une illusion d'optique interne", Revue Philosophique de la France Et de l'Étranger, vol. 3, 1877.

More info: National Diet Library Reference Cooperative Database

Pierre Janet (1859–1947)

A psychologist who was Paul's nephew. In his 1928 book, he introduced Paul's theory as one of the "theories on the concept of time" and popularized it as a law.

Pierre Janet, "L'évolution de la mémoire et de la notion du temps", 1928.

More info: National Diet Library Reference Cooperative Database

Scientific Evidence and Research

Psychological Mechanisms

  • Memory relativity: When fewer new experiences occur, the passage of time feels monotonous
  • Attention changes: Attention to novelty decreases with age, weakening time impressions
  • Physiological factors: Changes in neural transmission and brain processing speed affect time perception
  • Reference standard changes: Accumulated life experiences alter relative time perception

Current Research Trends

Recent neuroscience research reports that activity changes in brain regions involved in time perception (prefrontal cortex, parietal cortex, etc.) correlate with age. Changes in neurotransmitters like dopamine are also suggested to influence time perception.

Implementation in KIKI NEKO

Calculation Method

範囲： Calculation range: Ages 5–85 (80-year lifespan)

計算式： Integration of the reciprocal of age (from age 5 to 85)

重要な洞察： Key insight: Approximately half of perceived life passes by age ~20.6

Technical Implementation

  • Type-safe calculation processing with Next.js 15 and TypeScript
  • Data persistence with Firebase Firestore
  • Real-time calculation and countdown display
  • Dynamic calculation based on individual user age data

References & Materials

Academic Sources

  1. Janet, Paul. "Une illusion d'optique interne." Revue Philosophique de la France Et de l'Étranger 3 (1877).
  2. Janet, Pierre. "L'évolution de la mémoire et de la notion du temps." Paris: Chahine, 1928.
  3. Fraisse, Paul. "The Psychology of Time." Harper & Row, 1963.
  4. Zakay, Dan, and Richard A. Block. "Temporal cognition." Current Directions in Psychological Science 6.1 (1997): 12-16.
  5. Ichikawa, Makoto. "Introduction to the Psychology of Time: Mechanisms of the Mind that Create Time." Chuo Koron Shinsha, 2012.

Online Resources & Reference Sites

Wikipedia - Janet's Law

Basic explanation and overview of Janet's Law

https://ja.wikipedia.org/wiki/ジャネの法則

National Diet Library Reference Cooperative Database

Detailed academic information and sources on Janet's Law

https://crd.ndl.go.jp/reference/entry/index.php?page=ref_view&id=1000255467

Osaka University - Psychological Research on Time Perception

Academic research paper on time perception mechanisms

https://behavior.hus.osaka-u.ac.jp/2017/01A13004.pdf

Japan Society of Time Studies - Research on Time Cognition

Research report on time cognition and subjective time

https://www.jstage.jst.go.jp/article/ieiej/36/8/36_539/_pdf/-char/ja

Limitations and Precautions

Important Disclaimer

  • Janet's Law is an empirical rule and not a scientifically fully proven theory
  • Actual time perception may vary significantly due to individual differences and cultural backgrounds
  • This service's calculations are for educational and awareness purposes and are not medical or psychological diagnostic tools
  • They do not predict or guarantee actual lifespan or life duration

Individual Differences

Time perception is significantly influenced by the following factors: health status, lifestyle, occupation, hobbies and interests, social environment, cultural background, personality traits, and past experiences.

最終更新日: 2025年7月