Directional motion sensitivity under transparent motion conditions

We measured directional sensitivity to a foreground pattern while an orthogonally directed background pattern was present under transparent motion conditions. For both foreground and background pattern, the speed was varied between 0.5 and 28 deg sec(-1). A multi-step paradigm was employed which results in a better estimation of the suppressive or facilitatory effects than previously applied single-step methods (e,g, measuring D-max or D-min). Moreover, our method gives insight into the interactions for a wide range of speeds and not just the extreme motion thresholds (the D-values). We found that high background speeds have an inhibitory effect on the detection of a range of high foreground speeds and low background speeds have an inhibitory effect on a range of low foreground speeds, Intermediate background pattern speeds inhibit the detection of both low and high foreground pattern speeds and do so in a systematic manner. Copyright (C) 1996 Elsevier Science Ltd.