Lecture 3 Summary
The Embodied User
What are the necessary and sufficient conditions to fool our brain's "reality tests"
into believing we are physically there in a continuous and complete environment?
Lecture slides
Telepresence – Definition
Telepresence = the experience of "being there" in a mediated or virtual environment; the
(perceptual) illusion of non-mediation.
Coined by Marvin Minsky (1980) in the context of teleoperation systems
Pictorial realism is not a necessary condition for presence (Slater et al., 1999)
Narrative involvement is not a necessary condition either — presence is about form,
not content
Key Technological Factors for Telepresence
Vividness – number of sensory modalities addressed
Interactivity – extent to which user actions update the environment (closed action-
perception loops)
Sufficient conditions involve moving your head/arm and seeing the virtual display
update correspondingly — i.e., lawful sensorimotor contingencies
Take-Home Message
Understanding telepresence requires treating the user as an embodied agent — not
just a brain, but a biological body
All perception is mediated; due to the plasticity of body image and body schema,
tools and technologies can become transparent extensions of the self (Clark: we are
all cyborgs)
Telepresence depends on sensorimotor integration — we enact telepresence
There is nothing magical about telepresence: it is a natural consequence of how we
adapt to a slippery surface or the weight of a hammer
Metzinger's Orders of Embodiment
, Order Components
1st Morphology only
2nd Morphology + Body Schema
3rd Morphology + Body Schema + Body Image
1. Morphology
Physical form and features of the body: limbs, muscles, sensory receptors
Determines action possibilities and sensory experiences
First-order embodiment — hard-wired, rigid (e.g., Braitenberg vehicle)
Tools extend morphology physically (hammer, prosthesis, magnifying glass)
2. Body Schema
The non-conscious, anonymous performance of the body — a dynamic distributed
network of procedures guiding behavior
"A postural model of the body, constantly updated for position and movement in time
and space" (Head & Holmes, 1911)
There is no homunculus in the brain — the schema is a network of procedures, not a
central representation
Tools extend the body schema functionally:
Yamamoto & Kitazawa (2001): crossing sticks impairs temporal order judgments
like crossing arms
Iriki et al. (1996): monkey bimodal neurons expand receptive field to include a
rake after tool use
Berti & Frassinetti (2000): patient's near-space neglect expanded when using a
stick
Cardinali et al. (2009): arm kinematics altered after grabber use — body schema
elongated
3. Body Image
The higher-order consciousness of the body as owned — perceptions, feelings,
conceptual knowledge about one's body
Requires self-consciousness (only humans, great apes, dolphins, elephants, magpies
pass the mirror/rouge test)
The Embodied User
What are the necessary and sufficient conditions to fool our brain's "reality tests"
into believing we are physically there in a continuous and complete environment?
Lecture slides
Telepresence – Definition
Telepresence = the experience of "being there" in a mediated or virtual environment; the
(perceptual) illusion of non-mediation.
Coined by Marvin Minsky (1980) in the context of teleoperation systems
Pictorial realism is not a necessary condition for presence (Slater et al., 1999)
Narrative involvement is not a necessary condition either — presence is about form,
not content
Key Technological Factors for Telepresence
Vividness – number of sensory modalities addressed
Interactivity – extent to which user actions update the environment (closed action-
perception loops)
Sufficient conditions involve moving your head/arm and seeing the virtual display
update correspondingly — i.e., lawful sensorimotor contingencies
Take-Home Message
Understanding telepresence requires treating the user as an embodied agent — not
just a brain, but a biological body
All perception is mediated; due to the plasticity of body image and body schema,
tools and technologies can become transparent extensions of the self (Clark: we are
all cyborgs)
Telepresence depends on sensorimotor integration — we enact telepresence
There is nothing magical about telepresence: it is a natural consequence of how we
adapt to a slippery surface or the weight of a hammer
Metzinger's Orders of Embodiment
, Order Components
1st Morphology only
2nd Morphology + Body Schema
3rd Morphology + Body Schema + Body Image
1. Morphology
Physical form and features of the body: limbs, muscles, sensory receptors
Determines action possibilities and sensory experiences
First-order embodiment — hard-wired, rigid (e.g., Braitenberg vehicle)
Tools extend morphology physically (hammer, prosthesis, magnifying glass)
2. Body Schema
The non-conscious, anonymous performance of the body — a dynamic distributed
network of procedures guiding behavior
"A postural model of the body, constantly updated for position and movement in time
and space" (Head & Holmes, 1911)
There is no homunculus in the brain — the schema is a network of procedures, not a
central representation
Tools extend the body schema functionally:
Yamamoto & Kitazawa (2001): crossing sticks impairs temporal order judgments
like crossing arms
Iriki et al. (1996): monkey bimodal neurons expand receptive field to include a
rake after tool use
Berti & Frassinetti (2000): patient's near-space neglect expanded when using a
stick
Cardinali et al. (2009): arm kinematics altered after grabber use — body schema
elongated
3. Body Image
The higher-order consciousness of the body as owned — perceptions, feelings,
conceptual knowledge about one's body
Requires self-consciousness (only humans, great apes, dolphins, elephants, magpies
pass the mirror/rouge test)
