Copycat is a
model
A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure.
Models c ...
of
analogy making and human
cognition based on the concept of the
parallel terraced scan
The parallel terraced scan is a multi-agent based search technique that is basic to cognitive architectures, such as Copycat, Letter-string, the Examiner, Tabletop, and others. It was developed by John Rehling and Douglas Hofstadter at the Cent ...
, developed in 1988 by
Douglas Hofstadter,
Melanie Mitchell
Melanie Mitchell is an American scientist. She is the Davis Professor of Complexity at the Santa Fe Institute. Her major work has been in the areas of analogical reasoning, complex systems, genetic algorithms and cellular automata, and her publi ...
, and others at th
Center for Research on Concepts and Cognition Indiana University Bloomington
Indiana University Bloomington (IU Bloomington, Indiana University, IU, or simply Indiana) is a public research university in Bloomington, Indiana. It is the flagship campus of Indiana University and, with over 40,000 students, its largest ca ...
.
The original Copycat was written in
Common Lisp and is
bitrotten (as it relies on now-outdated graphics libraries for Lucid Common Lisp); however, Java and Python ports exist. The latest version in 2018 is
Python3 portby Lucas Saldyt and J. Alan Brogan.
Description
Copycat produces answers to such problems as "abc is to abd as ijk is to what?" (abc:abd :: ijk:?). Hofstadter and Mitchell consider analogy making as the core of high-level cognition, or ''high-level perception'', as Hofstadter calls it, basic to recognition and categorization.
High-level perception
emerges from the spreading activity of many independent processes, called ''codelets'', running in parallel, competing or cooperating. They create and destroy temporary perceptual constructs, probabilistically trying out variations to eventually produce an answer. The codelets rely on an associative network, ''slipnet'', built on pre-programmed concepts and their associations (a
long-term memory
Long-term memory (LTM) is the stage of the Atkinson–Shiffrin memory model in which informative knowledge is held indefinitely. It is defined in contrast to short-term and working memory, which persist for only about 18 to 30 seconds. Long- ...
). The changing activation levels of the concepts make a conceptual overlap with neighboring concepts.
Copycat's architecture is tripartite, consisting of a ''slipnet'', a ''working area'' (also called
workspace
Workspace is a term used in various branches of engineering and economic development.
Business development
Workspace refers to small premises provided, often by local authorities or economic development agencies, to help new businesses to estab ...
, similar to
blackboard system
A blackboard system is an artificial intelligence approach based on the blackboard architectural model, where a common knowledge base, the "blackboard", is iteratively updated by a diverse group of specialist knowledge sources, starting with a pro ...
s), and the ''coderack'' (with the codelets). The slipnet is a network composed of nodes, which represent permanent concepts, and weighted links, which are relations, between them. It differs from
traditional semantic networks, since the effective weight associated with a particular link may vary through time according to the activation level of specific concepts (nodes). The codelets build structures in the working area and modify activations in the slipnet accordingly (bottom-up processes), and the current state of slipnet determines probabilistically which codelets must be run (top-down influences).
Comparison to other cognitive architectures
Copycat differs considerably in many respects from other
cognitive architecture A cognitive architecture refers to both a theory about the structure of the human mind and to a computational instantiation of such a theory used in the fields of artificial intelligence (AI) and computational cognitive science. The formalized mod ...
s such as
ACT-R
ACT-R (pronounced /ˌækt ˈɑr/; short for "Adaptive Control of Thought—Rational") is a cognitive architecture mainly developed by John Robert Anderson and Christian Lebiere at Carnegie Mellon University. Like any cognitive architecture, ACT-R ...
,
Soar,
DUAL,
Psi
Psi, PSI or Ψ may refer to:
Alphabetic letters
* Psi (Greek) (Ψ, ψ), the 23rd letter of the Greek alphabet
* Psi (Cyrillic) (Ѱ, ѱ), letter of the early Cyrillic alphabet, adopted from Greek
Arts and entertainment
* "Psi" as an abbreviatio ...
, or
subsumption architecture Subsumption architecture is a reactive robotic architecture heavily associated with behavior-based robotics which was very popular in the 1980s and 90s. The term was introduced by Rodney Brooks and colleagues in 1986.Brooks, R. A., "A Robust Progr ...
s.
Copycat is Hofstadter's most popular model. Other models presented by Hofstadter et al. are similar in architecture, but different in the so-called microdomain, their application, e.g. Letter Spirit, etc.
Since the 1995 book ''
Fluid Concepts and Creative Analogies
''Fluid Concepts and Creative Analogies: Computer Models of the Fundamental Mechanisms of Thought'' is a 1995 book by Douglas Hofstadter and other members of the Fluid Analogies Research Group exploring the mechanisms of intelligence through compu ...
'' describing the work of the Fluid Analogies Research Group (FARG) book, work on Copycat-like models has continued: as of 2008 the latest models are Phaeaco (a
Bongard problem
A Bongard problem is a kind of puzzle invented by the Russian computer scientist Mikhail Moiseevich Bongard (Михаил Моисеевич Бонгард, 1924–1971), probably in the mid-1960s. They were published in his 1967 book on pattern re ...
solver), SeqSee (number sequence extrapolation), George (geometric exploration), and Musicat (a melodic expectation model). The architecture is known as the "FARGitecture" and current implementations use a variety of modern languages including C# and Java. A future FARG goal is to build a single generic FARGitecture software framework to facilitate experimentation.
See also
*
Artificial consciousness
*
LIDA (cognitive architecture)
*
Semantic pointer architecture
References
Further reading
* (1993)
*
External links
A short description of CopycatGithub repository of copycat implementation (and other FARG projects)The Copycat Project: A Model of Mental Fluidity and Analogy-Making(pdf)
A Python version of Copycat by J. Alan Brogan, 2012A Python version of Copycat by Joseph Hager, 2017* Abhijit Mahabal's Seqsee code i
Perland i
Python*
ttp://ericpnichols.com/musicat/ Eric Nichols' Musicat dissertationThe Letter Spirit page at the Center for Research on Concepts and Cognition{{Douglas Hofstadter
Cognitive architecture
Common Lisp (programming language) software