The Pulfrich phenomenon in a large population of young healthy subjects

Abstract

The Pulfrich phenomenon is perceived equally in both eyes. Depth perception without filters was not significantly different from zero. The illusion has clinical utility, since in normal subjects reliability of measurements is good and size of the illusion (without filters) small.

Influence of the Pulfrich phenomenon on driving performance

“…In good agreement with the theory of the Pulfrich effect, we found that smaller Pulfrich effects induced smaller car displacements [6,15,21,24] and that larger velocities were associated with larger car displacements [16]. We did not test the effect of a unilateral mydriasis on driving performance.…”

“…In such a situation, a moving object is perceived at an incorrect distance. Data from several psychophysical [3,6,12,15,16,21,34] and electrophysiological [4,32] investigations are consistent with the delay hypothesis. Other factors determining the magnitude of the stereophenomenon are pendulum velocity [16], level of illumination [15] and distance between observer and pendulum [17].…”

Computer-Based Test to Quantify the Pulfrich Stereophenomenon

“…The setup for the MP has been described in detail previously [24, 25]. Briefly, a black rod with a 4-mm diameter was oscillated in a frontal plane with simple harmonic motion by a motor-driven scotch yoke arrangement.…”

“…In normal subjects, the reliability of measurements is good, and the size of illusion without filters small [24]. …”

“…The most important question was whether or not a PP can be measured by inducing a phase shift between the pendulum perceived in the right eye and the one seen in the left eye. Exact quantification can be important for several reasons: (1) spontaneous elliptical movements of a small size are also found in normal subjects [24]; (2) this will allow determination of the time course of a spontaneous PP; (3) some patients require treatment with a tinted contact lens in front of the normal eye [26]. …”