Umwelt

German biologist Jakob von Uexküll (1864-1944) coined this term to describe the fact that different organisms can share the same environment, but because of differences (and limits) in sensory abilities, they experience this shared environment in very different ways. The word Umwelt means "the surrounding world", and the Umwelt will vary from agent to agent. "Every object becomes something completely different on entering a different Umwelt. A flower stem that in our Umwelt is a support for the flower, becomes a pipe full of liquid for the meadow spittlebug (Philaenus spumarius) who sucks out the liquid to build its foamy nest (Uexküll, 2001, p. 108).

A more modern version of the Umwelt appears in Gibson's (1979) ecological psychology: his notion of the environment (which cannot be defined independently of the agent within it) is an Umwelt variation. So too is his notion of affordance, which is also defined relative to the agent. In both cases, though, Gibson has extended the notion of Umwelt by including the notion of agent-based action (as in the action of a perceptual system) or possible action afforded to a particular agent. The Umwelt is important to embodied cognitive science, because it is recognized that an agent's experience of the world depends not only upon its sensory apparatus, but also upon its physical embodiment.

References:

1. Gibson, J. J. (1979). The Ecological Approach To Visual Perception. Boston, MA: Houghton Mifflin
2. Uexküll, J. v. (2001). An introduction to umwelt. Semiotica, 134(1-4), 107-110.

(Added November 2009)