A NEW STEREOTEST - THE DOUBLE 2-ROD TEST

A new stereoacuity test, the double two rod test, uses a two-alternati ve forced-choice (2AFC) paradigm. The subject's task is to state which pair of rods, the left or the right, contains depth information. The test gives repeatable results; comparison between the depth threshold measured binocularly and monocularly suggests that monocular cues, if present, provide only poor depth information, compared to the depth in formation arising from binocular disparity. As part of an investigatio n of stereoacuity and ageing, we tested stereoacuity as a function of viewing time and the number of comparisons made between the two pairs of rods, Stereoacuity was significantly reduced for viewing times less than 3s while longer viewing times did not improve stereoacuity. The number of comparisons made between the two pairs of rods had no effect on stereoacuity. Copyright (C) 1996 The College of Optometrists. Publ ished by Elsevier Science Ltd