Modern air-traffic control displays feature complex symbology that may negatively impact operator performance efficiency. Manipulations of stereoscopic depth have been proposed as a means to declutter such displays and thereby to enhance operator performance. In this study, we employed a flanker task designed by Eriksen and Eriksen (1974) to further investigate that possibility. Participants were required to correctly respond to target letters from the sets H and K and S and C that were bordered horizontally by response compatible and response incompatible flanking letters. Using a stereoscopic imaging technique, the flanking letters were made to appear .1 and .8 cm in front of or behind the target letters, or on the same plane as the target letters. Consistent with the findings of Eriksen and Eriksen (1974), when all letters appeared on the same plane, response times (RTs) to target letters in the presence of response incompatible flanking letters were significantly elevated in comparison to RTs in the presence of response compatible flanking letters. These effects were eliminated when the flankers appeared to be slightly in front of the target letters or at both distances behind the target letters. However, the flanker effects were restored when the flankers appeared well in front of the target letters. The results suggest that the decluttering ability of stereoscopic depth is complex and dependent on the relative apparent distance between the targets and their bordering flanker elements.