spreading activation

Meaning: In the network model of semantic memory, concepts are nodes joined by links. When a node is activated (by seeing, hearing, or thinking of it), activation spreads along the links to connected nodes. Closely related nodes receive more activation and stronger links carry more of it, so related information becomes more accessible for a short time. Activation fades with distance and with time.

On the MCAT: Passages describe a lexical decision task or word-recognition experiment. After seeing "doctor," participants identify "nurse" faster than "bread." This faster response is priming, and spreading activation is the proposed mechanism. Expect questions asking you to predict which target word is recognized fastest, to read a reaction-time graph, or to explain why a related cue aids recall. It is also used to explain why retrieval cues work and why associated memories come to mind together.

Common confusion: Spreading activation is not the same as priming. Priming is the observed effect (faster, more accurate response), while spreading activation is the explanation of how the effect occurs in a semantic network. It also differs from the serial position effect or from encoding specificity, which concern the order of items or the match between encoding and retrieval context. Finally, activation is automatic and temporary, not a deliberate search.