Do Arabic numerals activate magnitude automatically? Evidence from the psychological refractory period paradigm.

A single experiment (N = 30) tested the claim that Arabic numerals automatically activate their magnitude representations by assessing whether central attention is required in order to activate magnitude within the psychological refractory period (PRP) paradigm. Subjects performed a color discrimination task as Task 1 and a parity judgment task as Task 2. Task overlap was controlled by varying stimulus onset asynchrony (SOA). A spatial-numerical association of response codes (SNARC) effect arose in Task 2 and yielded under-additive effects with decreasing SOA. This result suggests that magnitude is activated prior to central attention, and is therefore consistent with the claim that numerals activate magnitude automatically.