View source for Ecological interface design

'''Ecological interface design''' (EID) is a framework for designing human-machine interfaces based on the [[Abstraction Hierarchy|abstraction hierarchy]] of Jens Rasmussen and the perceptual psychology of James Gibson. It was developed by Kim Vicente and Rasmussen in the 1990s as an alternative to traditional interface design approaches that focus on user preferences, task analysis, or feature checklists. The core principle of EID is that the interface should make the underlying constraints and properties of the work domain visible to the operator, enabling them to navigate the abstraction hierarchy as the situation demands.

== The Two Principles ==

EID is governed by two principles:

'''The principle of direct perception.''' The interface should present information in a form that supports the operator's direct perception of the work domain's properties, without requiring extensive cognitive inference. This is inspired by Gibson's ecological psychology, which holds that perception is not a process of constructing internal representations from sensory data but a process of directly picking up invariant properties (affordances) from the environment. The interface should be designed so that the operator can 'see' the system's state, its constraints, and its possibilities for action, without having to reason about them.

'''The principle of skill-, rule-, and knowledge-based behavior.''' Rasmussen's model of cognitive control distinguishes three levels of behavior: skill-based (automatic, perceptual-motor), rule-based (procedural, if-then), and knowledge-based (analytical, problem-solving). The interface should support all three levels, allowing the expert to act on skill-based perception while providing the novice with the knowledge-based information needed for learning. The interface is not a single display but a hierarchy of displays that map to the levels of the abstraction hierarchy.

== The Interface Hierarchy ==

In EID, the interface is organized as a set of displays that correspond to the levels of the abstraction hierarchy:

'''The work domain display.''' Shows the functional purpose, abstract function, and generalized function levels — the 'why' and 'how' of the system. This display supports knowledge-based behavior by making the system's goals and constraints visible.

'''The task display.''' Shows the physical function and physical form levels — the 'what' and 'where' of the system. This display supports rule-based behavior by presenting the procedures and actions relevant to the current task.

'''The sensor display.''' Shows the raw sensory data — the physical signals from the system. This display supports skill-based behavior by providing the perceptual cues that experts use for pattern recognition and direct response.

The operator can move between these displays as the situation demands, zooming out to the work domain display when the situation is novel and uncertain, and zooming in to the sensor display when the situation is familiar and urgent.

== Connection to Systems Theory ==

EID is a systems-theoretic approach to interface design because it treats the interface not as a collection of widgets but as a model of the work domain. The interface is a representation of the system's [[Feedback Topology|feedback topology]] — the network of constraints, goals, and physical properties that determine what the system can do. The operator's task is to navigate this topology, and the interface's job is to make the topology visible.

The connection to [[Cognitive psychology|cognitive psychology]] is direct: EID assumes that the operator's mental model of the system is the primary determinant of their performance, and that the interface should be designed to support the construction and maintenance of an accurate mental model. The connection to [[Situation Awareness|situation awareness]] is also direct: EID aims to support all three levels of Endsley's model by providing information that is relevant to perception, comprehension, and projection.

== See Also ==

* [[Abstraction Hierarchy]]
* [[Cognitive psychology]]
* [[Situation Awareness]]
* [[Mental model]]
* [[Human-Computer Interaction]]
* [[Feedback Topology]]
* [[Design]]

[[Category:Design]]
[[Category:Human-Computer Interaction]]
[[Category:Systems]]
[[Category:Cognitive Science]]