Center for Cognitive Brain Imaging

at Carnegie Mellon University


4CAPS Cognitive Neuroarchitecture


4CAPS is the most recent member of an architectural family that includes CAPS and 3CAPS.

The original CAPS architecture (Thibadeau et al., 1982) synthesizes symbolic and activation-based processing as it was understood in the early 1980s, and in this regard resembles other hybrid efforts of the time (Anderson, 1983; Hofstadter et al., 1983; Holland et al., 1985; Erman et al., 1980; Minsky, 1985; Rumelhart & McClelland, 1982). Its computational mechanisms include: variable-binding, constituent-structured representations, graded activations, weights, thresholds, and parallel processing. The suitability of CAPS for accounting for high-level cognition has been demonstrated by successful models of language comprehension (Just & Carpenter, 1987; Thibadeau et al., 1982), mental rotation (Just & Carpenter, 1985), and problem solving (Carpenter et al., 1990).

CAPS was succeeded by 3CAPS (Just & Carpenter, 1992; Just & Varma, 2002), which adds constraints on the resources available for maintaining and processing representations. This enables computational explorations of individual differences on a number of tasks: sentence comprehension in young adults of different working memory capacities (Just & Carpenter, 1992); sentence comprehension in intact neurotypicals and aphasics (Haarmann et al., 1997); discourse comprehension in young adults (Goldman & Varma, 1995); problem solving in neurotypical adults with different fluid intelligence (Just et al., 1996); problem solving in intact neurotypicals and patients with frontal lobe lesions (Goel et al., 2001); and human-computer interaction (Byrne & Bovair, 1997; Huguenard et al., 1997). The success of these models furthers the case that human information processing employs hybrid computational mechanisms in a capacity-constrained environment.

CAPS and 3CAPS models account for behavioral measures of high-level cognition collected from neurotypical young adults and neuropsychological patients, broadly defined. 4CAPS, the latest member of the CAPS family, extends to new measures and new populations. Like their predecessors, 4CAPS models account for the time course of cognition and for individual differences. Unlike their predecessors, they also account for neuroimaging measures of normal cognition, and they provide much more precise accounts of the behavioral consequences of cortical lesions.

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