Attentional scanning in the selection of central targets from multi-symbol strings

Subjects responded to five-symbol strings consisting of a central target, one or two compatible or incompatible flankers, and neutral symbols in the remaining positions. Performance strongly depended on the position of compatible or incompatible flankers. With normal letters, left-side flankers had a much larger impact than right-side flankers. This left-side asymmetry of the flanker compatibility effect disappeared with strings composed of spaced letters or of tiny pictures and tended to turn into a right-side asymmetry with vertically mirrored letters. These results seem to indicate the operation of attentional scanning processes. Flankers may be scanned either automatically, due to a reading-like habit, or strategically, in attempting to localize the target.