When a pure eye rotation is simulated using optic flow stimuli, the image contains distortions resulting from the changing orientation of the eye relative to the scene, that we term 'dynamic perspective cues' (see Kim et al., 2014 for more details).
For example, affine properties of shape are invariant to the relative orientation of the eye and the plane of a drawing motion.
In experiments by Solomon et al., a display with orthogonal gratings was used in which the orientation of left-eye target elements was the same as the orientation of the right-eye distractors.
Using video recordings, we measured the rate of two types of head movements: regular (head moves along a single axis and the direction of the eye-bill tip vector follows the head movement [31]) and translational (head moves along a combination of axes in a straight or curved path but without changing the orientation of the eye-bill tip vector [31], [33]).
Our criterion for recording a spider's 'choice' was met only when the spider stalked a virtual mosquito (i.e., with body lowered, the spider approached one of the two virtual mosquitoes while maintaining orientation of principal eyes toward this mosquito), reached the upper end of the ramp and either stopped and remained facing to this virtual mosquito for 30 s or else leapt on to it.
The orientation of the eyes was marked on the limbus at 12 O'Clock position before enucleating.
Prolonged MD caused mismatch of the preferred orientation of two eyes, consistent with requirement of binocular visual experience during the critical period to develop orientation matching (Wang et al., 2010).
For these trials, each of the six contrast levels was combined with any other level and this was done for both possible assignments of grating orientation to eye (72 = 6 × 6 × 2).
For a simulation of different horizontal gaze positions, the orientation of the artificial eye model was varied covering the horizontal extent of the presented sentences (from about -17° to +9° relative to the center of the screen).
For example, many combinations of eye orientation and location of stimulation on the retina correspond to a visual stimulus that is directly in front of the head.
