Why would performances between aIOVD and dIOVD stimuli that are supposed to isolate the same cue to motion-in-depth differ? Our stimuli were chosen based on the results by Czuba et al. [35] who found with their stimuli similar motion-coherence thresholds for FULL cue and aIOVD stimuli. The general, yet so far untested, assumption has been that both aIOVD and dIOVD stimuli isolate the IOVD mechanism by either rendering disparity information unusable (aIOVD) or by removing it (dIOVD) so that the detection and discrimination of motion-in-depth can only rely on the velocity information in the two eyes. No matter the method (aIOVD or dIOVD), this remaining velocity information should be very similar for the two types of IOVD stimuli since monocularly aIOVD and dIOVD stimuli were similar, i.e., the dots had the same size, contrast and, most importantly, the same monocular speed in the two eyes. The stimuli did also not differ systematically in other monocular cues (looming, optic flow) or in extra-retinal cues. Therefore, detection performances for aIOVD and dIOVD stimuli should be similar and should reflect the sensitivity of the IOVD mechanism.