Correlation of the two eyes during optokinesis under different stimulus conditions
| . | Butterflyfish . | Pipefish . | Sandlance . |
|---|---|---|---|
| Normal optokinesis | Yoked fast phase | Mainly independent fast phase | Independent fast phase |
| Split drum stimulation | Disjunctive fast and slow phase, slow phase gain linked, convergence to temporo-nasal stimulation | Independent fast and slow phase, independent slow phase gain | Independent fast and slow phase, independent slow phase gain |
| Monocular stimulation with visual feedback to contralateral eye | Yoked optokinesis, seeing eye drives eye that views stationary grating | Independent slow phase, fast eye movement sometimes linked, but no optokinesis in contralateral eye | Independent slow and fast phase, no optokinesis in contralateral eye |
| Monocular stimulation, contralateral eye occluded | Yoked optokinesis, seeing eye drives occluded eye | Yoked slow phase, fast phase largely independent | Independent slow and fast phase, no optokinesis in contralateral eye |
| . | Butterflyfish . | Pipefish . | Sandlance . |
|---|---|---|---|
| Normal optokinesis | Yoked fast phase | Mainly independent fast phase | Independent fast phase |
| Split drum stimulation | Disjunctive fast and slow phase, slow phase gain linked, convergence to temporo-nasal stimulation | Independent fast and slow phase, independent slow phase gain | Independent fast and slow phase, independent slow phase gain |
| Monocular stimulation with visual feedback to contralateral eye | Yoked optokinesis, seeing eye drives eye that views stationary grating | Independent slow phase, fast eye movement sometimes linked, but no optokinesis in contralateral eye | Independent slow and fast phase, no optokinesis in contralateral eye |
| Monocular stimulation, contralateral eye occluded | Yoked optokinesis, seeing eye drives occluded eye | Yoked slow phase, fast phase largely independent | Independent slow and fast phase, no optokinesis in contralateral eye |
The results clearly show differences in the degree of correlation between the two eyes in the species studied. The emerging picture is that of a sliding scale of conjugacy, revealing different linkage strengths between the eyes of the different species.