The Optical Basis of Time-to-Contact Judgments
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In spite of the high correlation between judgments and ~bar, the absence of a useful event property associated with this variable makes our finding curious. The purpose of the present paper was to determine whether the higher correlations of te judgments with ?bar than tau is a general phenomenon or whether it was an artifact of the display conditions, namely, the use of a constant size-distance ratio (i.e., a constant initial optical size). First, we wanted to test if this relation would hold when more than one object-size/distance ratio, resulting in different optical sizes, is used. If, despite our previous findings, tau is used to time responses, then no differences should be found between the two size/distance ratios. Tau is independent of this ratio since it appears in both the numerator and denominator. Usage of ~bar, however, should lead to different responses with different image sizes.