4.5 Globalist versus Localist Representations 93
informative about the emotion, so that positioning an emotion on the given dimensions tells one a. lot.
4.5.12 Knowledge Representation, Action Selection and Planning in Psi
In addition to the basic motivation/emotion architecture of Psi, which has been adopted (with some minor changes) for use in CogPrime, Psi has a number of other aspects that are somewhat different from their CogPrime analogues.
First of all, on the micro level, Psi represents knowledge using structures called “quads.” Each quad is a cluster of 5 neurons containing a core neuron, and four other neurons representing before/after and part-of/has-part relationships in regard to that core neuron. Quads are natu- rally assembled into spatiotemporal hierarchies, though they are not required to form part of such a structure.
Psi stores knowledge using quads arranged in three networks, which are conceptually similar to the networks in Albus’s 4D/RCS and Arel’s DeSTIN architectures:
e A sensory network, which stores declarative knowledge: schemas representing images, ob- jects, events and situations as hierarchical structures.
e A motor network, which contains procedural knowledge by way of hierarchical behavior programs
e A motivational network handling demands
Perception in Psi, which is centered in the sensory network, follows principles similar to DeSTIN (which are shared also by other systems), for instance the principle of perception as prediction. Psi’s “HyPercept” mechanism performs hypothesis-based perception: it attempts to predict what is there to be perceived and then attempts to verify these predictions using sen- sation and memory. Furthermore HyPercept is intimately coupled with actions in the external world, according to the concept of “Neisser’s perceptual cycle,” the cycle between exploration and representation of reality. Perceptually acquired information is translated into schemas ca- pable of guiding behaviors, and these are enacted (sometimes affecting the world in significant ways) and in the process used to guide further perception. Imaginary perceptions are handled via a “mental stage” analogous to CogPrime’s internal simulation world.
Action selection in Psi works based on what are called “triplets,” each of which consists of
e asensor schema (pre-conditions, “condition schema”; like CogPrime’s “context”) e a subsequent motor schema (action, effector; like CogPrime’s “procedure”) e a final sensor schema (post-conditions, expectations; like an CogPrime predicate or goal)
What distinguishes these triplets from classic production rules as used in (say) Soar and ACT-R is that the triplets may be partial (some of the three elements may be missing) and may be uncertain. However, there seems no fundamental difference between these triplets and CogPrime’s concept /procedure/goal triplets, at a high level; the difference lies in the underlying knowledge representation used for the schemata, and the probabilistic logic used to represent the implication.
The work of figuring out what schema to execute to achieve the chosen goal in the current context is done in Psi using a combination of processes called the “Rasmussen ladder” (named
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