AXIS OF ELONGATION CAN DETERMINE REFERENCE FRAMES FOR OBJECT PERCEPTION

Object perception remains constant in the face of much retina image va riability. One way to achieve such constancy is to represent objects w ith respect to a reference frame, and many theories of object recognit ion assume that, among other factors, observers use objects' primary a xes of elongation to derive reference frames. However, the limited res earch directly addressing this assumption suggests that the role of ax is of elongation may not be as central as previously thought (Palmer, 1990; Quinlan & Humphreys, 1993). The present study reexamines elongat ion's role in determining reference frames, adapting Palmer's paradigm to determine the extent to which surrounds bias the perception of amb iguously oriented objects: equilateral triangles. When surrounds were oriented inconsistently with experimentally constrained correct respon ses, response times increased with surrounds' elongation. These result s hold for both symmetric and asymmetric surrounds, suggesting that el ongation alone is sufficient to construct a reference frame for object perception.