Priming Single Digit Numbers: Automatic Spreading Activation Dissipates as a Function of Semantic Distance

The most commonly referenced model of semantic priming is the spreading activation model of Collins and Loftus (1975). The model asserts that concepts activated in a semantic network by a prime serve as a source of activation that spreads to other nearby (related) concepts. Activation of these nearby nodes serves to lower their thresholds, which in turn facilitates the processing of targets matching these activated nodes. Priming, therefore, facilitates the processing of related targets. Spreading activation is assumed to dissipate with distance. In effect, distance represents the degree to which two concepts are related. It is argued that although the distance assumption is addressed in the experimental literature, an adequate test of this assumption has not been performed as yet. The present research tests the distance assumption by using single digit stimuli for the sets where prime and target are related. Using a lexical decision in one experiment and a letter-digit classification task in four others, it was found that the amount of facilitation varies inversely with the numerical distance between the prime and target and that this distance effect is largely the same in both the forward (e.g., five-seven) and backward (e.g., seven-five) directions. The results are interpreted to support the assumption that spreading activation dissipates with distance.