Nontarget columns and parafoveal target identification: Some limits on previously observed effects

Three experiments were conducted to determine limits to the phenomenon in which a column of nontargets to the foveal side of a parafoveally presented target is more detrimental to identification than a column to the target's peripheral side, while a single nontarget to the peripheral side is more disruptive. Experiments 1 and 2 showed that proximity of nontarget characters in a column is not sufficent to produce the difference in the effect of the position of nontarget columns and single nontargets. Physical features of characters in the column allowing closure emerged as important to the effect of its position on target identification. Experiment 3 confirmed the findings of the first two experiments and showed, in addition, that performance is better with nontarget columns than with single nontargets because characters in the columns exert lateral interference on one another and thereby release such interference on the target.