“…First, processing of line orientation in visual search or detection tasks is effortless, provided the orientations of the target and distractors are sufficiently different (e.g., Foster & Ward, 1991a, 1991bMarendaz, Stivalet, & Genon, 1991;Nothdurft, 1991). Second, orientation acuity is better for vertical or horizontal orientations than for oblique orientations, suggesting that horizontal and vertical are treated as reference orientations (Appelle, 1972;Heeley, Buchanan-Smith, Cromwell, & Wright, 1997;Orban, Vandenbussche,& Vogels, 1984;Vogels & Orban, 1985). Third, for orientations deviating by a small amount (about 20º) from the vertical, search for oriented lines shows an asymmetry: Search for a tilted target among vertical distractors is fast and accurate, whereas search for a vertical target among tilted distractors is slow and inefficient Cavanagh, Arguin, & Treisman, 1990;Foster & Ward, 1991a, 1991bMarendaz, 1998;Marendaz, Stivalet, Barraclough, & Walkowiac, 1993;Marendaz et al, 1991;Meigen, Lagreze, & Bach, 1994;Treisman, 1985;Treisman & Gormican, 1988).…”