do, and consequently, the interaction that could take place. Perception and action were co-determined by the effectivities and affordances, which acted 'in the moment' together. Therefore, the agent directly perceived and interacted with the environment, determining what affordances could be picked up, based on his effectivities. This view is consistent with Norman's (1988) theory of "perceived affordances," which emphasizes the agent's perception of an object's utility as opposed to focusing on the object itself. An interesting question is the relationship between affordances and mental representations as set forth in a more cognitivist perspective. While Greeno (1998) argues that attunements to affordances are superior to constructs such as schemata and mental models, Glenberg & Robertson (1999) suggested that affordances are the building blocks of mental models. Perception (variance/invariance) The work of Gibson (1986) in the field of visual perception greatly influences situated cognition. Gibson argued that visual perception is not a matter of the eye translating inputs into symbolic representation in the brain. Instead the viewer perceives and picks up on the infinite amount of information available in the environment. Specifically, an agent perceives affordances by discovering the variants, what changes, and more importantly the invariants, what does not change across different situations. Given a specific intention (or intentional set), perceptions of invariants are co-determined by the agent and the affordances of the environment, and are then built upon over time. Memory Situated cognition and ecological psychology perspectives emphasize perception and propose that memory plays a significantly diminished role in the learning process. Rather, focus is on the continuous tuning of perceptions and actions across situations based on the affordances of the environment and the interaction of the agent within that environment (Greeno, 1994). Representations are not stored and checked against past knowledge, but are created and interpreted in activity (Clancey, 1990). Situated cognition understands memory as an interaction with the world, bounded by meaningful situations, that brings an agent toward a specified goal (intention). Thus, perception and action are co-determined by the effectivities and affordances, which act 'in the moment' together. Therefore, the agent directly perceives and interacts with the environment, determining what affordances can be picked up, based on his effectivities, and does not simply recall stored symbolic representations. Knowing Situativity theorists recast knowledge not as an entity, thing, or noun, but as knowing as an action or verb. It is not an entity which can be collected as