Effects of roll and pitch components in retinal flow on heading judgement

We investigated effects of roll (rotation around line of sight) and pitch (rotation around the horizontal axis) components of retinal flow on heading judgement from visual motion information. It was found that performance level of human observers for yaw (rotation around the vertical axis) plus pitch is little different from that for only yaw although there is bias in perceived heading toward the fixation point, and that heading judgement is fairly robust with respect to roll. It was also found that there are some observers who can perceive heading with pitch, yaw and roll at a roll rate of 11.5 degrees /s without extra-retinal information. It suggests that there exist compensation mechanisms for roll in the human visual system.