Digits affect actions: the SNARC effect and response selection.

The SNARC (spatial-numerical association of response codes) effect refers to the finding that processing digits can modulate response times, with low digits facilitating left responses and high digits facilitating right responses. Recent evidence indicates that the locus of this effect is in the response selection stage. To examine this possibility, we presented participants with low or high digits and then asked them to make one of two keypresses (left or right) - whichever one they felt more comfortable making. The results showed that low digits biased the selection of left keypresses while high digits biased the selection of right keypresses. Thus, the SNARC effect not only affects how fast responses can be initiated but also affects what responses will be selected.