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Vernon, D., Metta, G. & Sandini, G. (2007). A Survey of artificial cognitive systems:
Implications for the autonomous development of mental capabilities in computational agents.
IEEE Transactions on evolutionary computation, 11(2), 151-180.
@Article{VeronMettaSandini2007,
author = {David Vernon and Giorgio Metta and Giulio Sandini},
title = {A Survey of artificial cognitive systems: Implications for the
autonomous development of mental capabilities in computational agents. IEEE Transactions on evolutionary computation},
journal = {IEEE Transactions on evolutionary computation},
year = {2007},
volume = {11},
pages = {151--180}
}
Cite this paper for:
- Overview of autonomous development of mental capabilities in computational agents.
- Cognitvist, emergent and hybrid system paradigms
- Characteristics of autonomous cognitive systems.[p151]
- Cognitivist approaches rely upon symbolic representations, which instantiate representations physically
as cognitive codes. [p.152]
- Emergent approaches purport systems which are viable and effective in both expected and novel environments
through autonomous processes of self-organization [p. 155].
- Cognivist, emergent and hybrid cognitive architectures.
- SYSTEM: DARWIN, Neuromimetic, Brain-based Device [p168]
- SYSTEM:Kismet cognitive architecture [p171]
- Autopoietic and operationally-closed systems [p172]
- Perception/Action codependency [174-5]
The actual paper can be found in
"IEEE Transactions on evolutionary computation, 11(2), 151-180."
Definition of Cognition [p151]
Cognition is an integrated process which "achieves robust adaptive, anticipatory, autonomous behavior,
entailing embodied perception and action." [p151]
Embodiment is key to cognition, with strong ties found between perception,
action and cognition. Intention, emotion and action are key grounding components of cognition.
Table 1, The Cognitivist vs. Emergent Paradigms of Cognition [p153]:
Each paradigm is compared according to key characteristics:
- ..characteristic: cognitivist vs. emergent
- computational operation: syntactic vs. network organization
- representation framework: symbolic token patterns vs. global system states
- semantic grounding: association of symbol & percept vs. construction of skills
- temporal constraints: temporal independence vs. real-time entrainment
- inter-agent epistemology: independent vs. dependent
- embodiment: not inferred vs. cognition implies embodiment
- perception: abstract symbols vs. agent response to "perturbation" [p153]
- action: caused by manipulation of symbols vs. system impacting the environment
- anticipation: reasoning by procedural or probability models vs. exploration of percept-action domain
- adaptation: new knowledge vs. new dynamics
- motivation: problem-solving vs. expansion of agent/environment integration
- relevance of autonomy: may not be implied vs. directly implied by definition
Description of cognitivist systems:
Cognitivist systems can also be described as physical symbol information-processing systems. [p153]
See Figure 1: The Essence of a Physical Symbol System [p 154]
Cognitivist systems describe behaviors as consequences of cognitive code operations. [p152]
Cognitivist systems are limited by human input such as bayesian networks (with predetermined probabilities)
and by semantic structures. [p154-5]
Re: artificial intelligence- cognitivist systems utilize physical symbol processing
and heuristic search methods for problem-solving. [p154]
A cognitive visual system which interprets traffic video input is an example of a cognitivist-type system.
Description of emergent systems:
Emergent systems include the concept of co-determinism- whereby the agent acquires sensory information
from the environment in order to construct its reality and to effect itself upon the environment using a
reflexive and real-time process.[p155]
Three sub-types of emergent systems are:
- connectionist- networks based on parallel distributed processing [p157]
- dynamical- more theory than practice, whereby open systems use non-linear methods to construct
real-time "realities" of itself and the enviroment- used more for system analysis then AI [p157-159] and,
- enactive models-autopoietic systems driven by self-maintenance. [p159].
See page 159 for a full description of the three levels of autopoietic systems.
Bickhard's autonomy and stability theories outlined [p160]:
Two types of autonomy exist: 1) self-maintenance- where agents contribute to their persistance and,
2) recursive self-maintenance- where agents also contribute to the conditions of their
persistance as per environmental shifts.
Two types of stability exist: 1) energy well stability (closed system with thermodynamic equilibrium)
and 2) far from equilibrium stability (open system with no thermodynamic equilibrium)
Description of hybrid systems:
Hybrid models or systems may use representation of percepts but operate without the constraints
of a priori programmer knowledge systems.
Cognitive Architectures
Cognitivist architectures are the
a priori "representational assumptions,
the characteristics of its memories, and the processes that operate
on those memories." [p162]
Emergent architecture are structures for the "perception, action, adaptation, anticipation,
and motivation that enable the ontogenetic development over the system’s lifetime." [p162]
Table 2, Cognitive Architectures Reviewed... [p163]:
- Cognitvist: Soar, EPIC, ACT-R, ICARUS, ADAPT
- Emergent: AAR, Global Workspace, I-C SDAL, SASE, DARWIN
- Hybrid: HUMANOID, Cerebrus, Cog: Theory of Mind, Kismet
Examples of Cognitivist Architectures [p163-6]
- Soar (Newell, 1990)- decision-making productions using universal sub-goals for impasses
- EPIC (Kieras & Meyer, 1997)- (Executive Process Interactive Control)- cognitive processor using parallel
production rules for sensory-motor tasks. Executive function governs resource sharing.
- ACT-R(Anderson, 1996)- (Adaptive Control of Thought- Rational)- modules and buffers "mimic" brain areas.
See Figure 2: ACT-R Cognitive Architecture [p164]
and utilize production rules to effect sensory-motor tasks. Goal module tracks intention.
- ICARUS (Langley, 2004)- Represents skills and concepts differently. Operations include
pattern matching and backward chaining is used at impasses.
- ADAPT (Benjamin et al,2004)- (adaptive dynamics and active perception for thought)-
combines features of Soar, EPIC and ACT-R to run
sequential architecture tasks (such as task initiation) but
multiple action tasks (pick up object) may be run in parallel.
Examples of Emergent Architectures [p166-9]
- AAR (Brooks, 1986)- Subsumption architecture beginning with simple
whole systems with increasingly sophisticated layers.
- Global Workspace (Shanahan, 2006)- Internal and external sensori-motor loops compete
cortically and concurrently to effect a "winner take all" decision.
See Figure 3 and 4: The global workspace theory cognitive architecture: “winner-take-all”
coordination of competing concurrent processes [p167] and "achieving prospection by sensorimotor simulation [p168]
- I-C SDAL (Christensen & Hooker, (2000)- a norm matrix regulates actions that focus on self-maintenance
and adaptive development of skills.
- SASE (Weng, 2002,2004)- Phylogeny is fixed without knowledge of future tasks.
Development occurs ontogenetically with only sensory input from environment.
See Figure 5: SASE cognitive architecture [p168]
- DARWIN (Kirchmar et al, 2005)-Neuromimetic "brain-based device". Agent utilizes neural areas,
neuronal units and synaptic connection (+1 million).
The DARWIN VIII uses Hebbian rules and recognizes and has preferences for geometric shapes,
DARWIN IX simulates rat's whiskers to navigate and categorize objects,
and DARWIN X can develop a spatial and episodic memory of objects and locations using visuo-detectors and odometry.
Examples of Hybrid Architectures [p169-171]
- HUMANIOD (Burghart et al, 2005)- Parallel processing of three levels each of perception and task subsystems
which is organized via a global knowledge data base (which uses representational schemas)
- Cerebrus (Horswill, 2001)- Performs reasoning about "itself" using a behaviour-based sensorimotor system with
distributed semantic rule-based network in order to move away
from the central processing models (such as in ACT-R)
- Cog: Theory of Mind (Scassellati, 2002)- Upper torso robot designed to model and
learn social interaction tasks (attribution of beliefs, goals etc)
- Kismet (Breazeal, 2000)- Robotic head which engages people in face to face interaction.
Kismet goal is to learn from people via social
interaction. Operates via homeostatic goal states of"drives" such as social, stimulation and fatigue.
See Figure 6: Kismet Cognitive Architecture.
Table 3, Cognitive Architectures vis a vis seven of the twelve characteristics... [p172]:
Table quickly demonstrates which architectures exhibit the desirable characteristics of autonomy.
SASE And DARWIN exhibit the most with all
characteristics represented either strongly or weakly.
The Developmental Stance [p172-5]:
See Figure 7: Maturana & Varela's ideograms to denote autopoietic and operationally closed systems.. (1987)
Architecture's phylogenetic structures must support motivation and structures for development. Similar to Kelsova(1995).
Co-determinism and self-organization capabilities are important features of development.
Learning (von Hofsten, 2004) [p173] and exploration are key elements of development.
Metzoff & Moore (2002) suggest imitation is key to learning-
with four phases: 1) body babbling, 2) imitation of body movements,
3) imitation of actions on objects and 4) imitation based on inferences re:
other;s intentions.
Winograd & Flores (1986) suggest that learning is not the increased databank of representations from the environment,
but is the continued refinement of behaviour based on satisfying internal or external demands.
This leads to co-dependency of perception and actions...."mirror neurons" [p175].
Recommended Key features of autonomous cognitive systems [p175-6]:
Based on Kirchmar et al (2005) design principles for autonomous development of systems.
- network of distributed subsystems which compete and cooperate to achieve goals
- modification of phylogeny and system dynamics must be possible
- anticipatory capabilities are needed (ie. to rehearse possible options)
- agent must have characteristics of embodiment (Ziemke, 2001) "structural coupling with the environment" [p176]
Summary author's notes:
- Many of the architectures described (particularly emergent) are still in development. A summary of the success
or developer's plans for modifications would be helpful so that the reader may be aware of what features of the architecture are
contributing most to the theory development.
- Very good overview of current archetypes of cognitive architectures and the supporting theories driving their development.
- Authors seem to favour emergent rather than cognitivist theory and thereby offer more critique of the cognitivist architectures.
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