Stroop and Garner effects in comparative judgment of numerals: The role ofattention

In 7 experiments, participants selected the larger member of pairs of digit s that differed in numerical magnitude as well as in physical size. Selecti ve attention to the relevant dimension (number or size) was gauged by Garne r and Stroop interference, both of which varied considerably as a function of the number and relative discriminability of values along the constituent dimensions. When the to-be-ignored dimension was more discriminable, sizab le Garner and Stroop effects affected performance on the relevant dimension . When it was less discriminable, Garner and Stroop effects were considerab ly smaller regardless of whether the relevant dimension was numerical or ph ysical size. The sensitivity of Stroop interference to manipulations of dis criminability is accounted for by the allocation of attention to the consti tuent dimensions. The demonstrated malleability of the Stroop effect is inc ompatible with claims of strong automaticity in numerical processing.