Mind, Body, World- Foundations of Cognitive Science, 2013a

which make use of the knowledge attained, and the processes by which transition
takes place from the initial to the final state, that is, language acquisition” (pp. 201–
202). An account of the processes that underlie performance requires an investigation
at the algorithmic level.
Finally, Marr (1982) noted that Chomsky’s notion of linguistic competence parallels
the computational level of analysis. A theory of linguistic competence specifies
an ideal speaker-listener’s knowledge of language (Chomsky, 1965). A grammar
is a theory of competence; it provides an account of the nature of language that
“is unaffected by such grammatically irrelevant conditions as memory limitations,
distractions, shifts of attention and interest, and errors (random or characteristic)
in applying . . . knowledge of the language in actual performance” (p. 3). As a computational-level
theory, a grammar accounts for what in principle could be said or
understood; in contrast, a performance theory accounts for language behaviours
that actually occurred (Fodor, 1968b). Marr (1982) argued that influential criticisms
of Chomsky’s theory (Winograd, 1972a) mistakenly viewed transformational
grammar as an algorithmic, and not a computational, account. “Chomsky’s theory
of transformational grammar is a true computational theory . . . concerned solely
with specifying what the syntactic decomposition of an English sentence should be,
and not at all with how that decomposition should be achieved” (Marr, 1982, p. 28).
The notion of the cognitive vocabulary arises by taking a different approach to
linking Marr’s (1982) theory of vision to Chomsky’s (1965) theory of language. In
addition to proposing the tri-level hypothesis, Marr detailed a sequence of different
types of representations of visual information. In the early stages of visual processing,
information was represented in the primal sketch, which provided a spatial representation
of visual primitives such as boundaries between surfaces. Operations on the
primal sketch produced the 2½-D sketch, which represents the properties, including
depth, of all visible surfaces. Finally, operations on the 2½-D sketch produce the 3-D
model, which represents the three-dimensional properties of objects (including surfaces
not directly visible) in a fashion that is independent of view.
Chomsky’s (1965) approach to language also posits different kinds of representations
(Jackendoff, 1987). These include representations of phonological structure,
representations of syntax, and representations of semantic or conceptual structures.
Jackendoff argued that Marr’s (1982) theory of vision could be directly linked to
Chomsky’s theory of language by a mapping between 3-D models and conceptual
structures. This link permits the output of visual processing to play a critical role in
fixing the semantic content of linguistic representations (Jackendoff, 1983, 1990).
One key element of Jackendoff ’s (1987) proposal is the distinction that he
imposed between syntax and semantics. This type of separation is characteristic of
classical cognitive science, which strives to separate the formal properties of symbols
from their content-bearing properties (Haugeland, 1985).
Marks of the Classical? 351