Masahiro Mori is a Japanese roboticist and Buddhist thinker whose 1970 essay “Bukimi no Tani Genshō” (不気味の谷現象, later translated as “The Uncanny Valley”) fundamentally shaped how designers approach human-like artificial entities. His concept of the uncanny valley has influenced decades of robot, animation, and AI design, establishing a critical framework for understanding human psychological responses to non-human entities that appear almost—but not quite—human.

The Uncanny Valley Hypothesis

Mori’s most significant contribution is the identification of a critical phenomenon in human-robot interaction:

Core Concept: Mori proposed that as robots become more human-like in appearance and movement, human affinity for them increases—but only up to a certain point. When robots become very human-like but still noticeably artificial, they trigger a strong feeling of unease or revulsion (the “uncanny valley”).
Visual Model: He presented this relationship as a graph, with human likeness on the x-axis and affinity on the y-axis, showing a dramatic dip (the “valley”) before reaching complete human resemblance.
Movement Factor: Mori emphasized that movement amplifies the effect—a moving almost-human entity is more unsettling than a static one.
Examples: He illustrated his theory using examples ranging from industrial robots and prosthetic hands to corpses and zombies, placing them along the continuum of human likeness and emotional response.
Design Implications: Mori suggested that designers should avoid this valley, either by making robots obviously non-human or by striving for perfect human replication—though he advised pursuing the former approach.

Background and Career

Mori’s work spanned both technical and philosophical domains:

Academic Career: Served as a professor at the Tokyo Institute of Technology where he conducted robotics research.
Robotics Work: Focused on robotic hands and prosthetics, practical areas that informed his theories about human responses to artificial limbs.
Buddhist Influence: His thinking was significantly shaped by Buddhist philosophy, particularly concepts of human nature and spiritual presence.
Later Career: Founded the Mukta Research Institute, which explored connections between robotics, Buddhism, and human existence.
Public Recognition: While initially his work received modest attention, the uncanny valley concept eventually gained international recognition and influenced global design practices.

Cultural Impact

Mori’s ideas have had far-reaching influence:

Design Philosophy: His theory has guided design choices for robots, animated characters, and virtual humans across industries, with many designers deliberately creating stylized rather than realistic characters to avoid the uncanny valley.
Japanese Robotics: In Japan, his ideas influenced many robot designers to favor cute, clearly non-human appearances for social robots (like Sony’s AIBO) rather than pursuing realism.
Global Lexicon: “Uncanny valley” has entered the general lexicon as a concept applied beyond robotics to fields including CGI animation, video game design, prosthetics, and AI development.
Academic Research: Sparked decades of research into human perception of non-human entities, with scholars across disciplines testing and expanding on his hypothesis.
Philosophical Discourse: His work bridges engineering and philosophy, raising questions about what makes humans respond to artificial entities as social beings.

Perspective on Human-Robot Relationships

Beyond the uncanny valley, Mori articulated broader views on robotics:

Buddhist Framework: He approached robotics through a Buddhist lens, considering how artificial creations relate to concepts of consciousness and being.
Beyond Replication: Mori cautioned against the goal of perfectly replicating humans, suggesting that robots should develop along their own path rather than simply mimicking human form.
Spiritual Elements: He explored the idea that human response to robots involves spiritual and emotional dimensions beyond mere visual recognition.
Ethics of Creation: Raised early questions about the ethical implications of creating increasingly human-like machines.
Harmony Priority: Emphasized that robot design should prioritize harmonious human-robot relationships rather than technical achievement for its own sake.

Connection to Digital Twins

Mori’s work has implications for digital twin development:

His insights help explain why photorealistic digital humans often fail to create comfort and engagement compared to stylized representations.
The uncanny valley suggests potential challenges in creating digital twins that replicate human appearance but may fall short on behavior or micro-expressions.
Alternative approaches to digital twin representation may be more effective by deliberately avoiding hyperrealism in favor of stylized representations.
Digital twins with animated or cartoon-like representations may create stronger affinity than those striving for perfect human replication.

Connections

Influenced the design philosophy behind AIBO and other Japanese robots
Core concept relevant to Japanese AI Companionship
Work connected to Japanese Techno-Animism
Ideas applied in development of Physical AI Embodiment
Concept informs design decisions in Digital Twins
Research related to AI Personhood issues
Work contrasts with approach of Hiroshi Ishiguro who deliberately explores the uncanny valley