The information processing approach to human cognition, which emerged in the late 1950s, treats the mind as a system that encodes, transforms, stores, and retrieves information. Inspired by Shannon's information theory and the architecture of digital computers, this framework was articulated by Donald Broadbent (1958) in Perception and Communication and formalized by Richard Atkinson and Richard Shiffrin (1968) in their influential multi-store model. The approach transformed cognitive psychology from a discipline dominated by behaviorism into a science of mental computation.
Stage Models of Processing
If factors A and B affect different stages:
RT(A,B) − RT(A,b) = RT(a,B) − RT(a,b) (additivity)
Interaction → factors affect a common stage
Additivity → factors affect separate stages
Saul Sternberg's (1969) additive factors method provided a rigorous technique for identifying processing stages from reaction time data. If two experimental factors have additive effects on RT, they are inferred to affect different processing stages; if they interact, they affect at least one common stage. This logic allowed researchers to decompose complex cognitive tasks into constituent stages and to map the functional architecture of information processing.
The Atkinson-Shiffrin Model
The Atkinson-Shiffrin (1968) multi-store model proposed three memory systems: a sensory register (brief iconic or echoic memory), a limited-capacity short-term store (STS), and a long-term store (LTS). Information flows from sensory registration through attention-gated transfer into STS, where rehearsal processes determine whether it is encoded into LTS. This serial architecture provided the first comprehensive quantitative model of human memory and generated decades of productive research.
Broadbent's (1958) filter model proposed that information processing has an early bottleneck: a selective filter that passes only attended information to higher processing. Later models by Treisman (1964) and Deutsch and Deutsch (1963) debated whether the bottleneck is early (perceptual) or late (response). Baddeley and Hitch (1974) replaced the unitary short-term store with a multi-component working memory system — a central executive, phonological loop, and visuospatial sketchpad — resolving several empirical puzzles and providing a more flexible architecture.
Modern Perspectives
Contemporary cognitive science has largely moved beyond strict serial stage models toward parallel, interactive, and cascaded architectures. McClelland's (1979) cascade model allows partial activation to propagate between stages before processing at each stage is complete. Miller and Hackley (1992) used lateralized readiness potentials to show that response preparation can begin before stimulus identification is finished, supporting continuous rather than discrete information flow.
Despite these refinements, the information processing framework remains foundational. The decomposition of cognition into functionally distinct operations — encoding, comparison, decision, response execution — continues to organize research in attention, memory, language, and cognitive control. The framework also provides the conceptual bridge between information theory and cognitive psychology, connecting Shannon's abstract channel to the concrete architecture of the human mind.