Table 1.
Previous studies of the shear between corresponding points.
| Citation | Subject | θv (deg) | θh (deg) | θr (θv − θh) (deg) |
|---|---|---|---|---|
| Helmholtz (1925) | HHa | 2.66 | 0.3 | 2.36 |
| WVb | 2.13 | – | – | |
| WVa | 2.15 | – | – | |
| FSb | 1.32 | – | – | |
| FSa | 1.44 | – | – | |
| Nakayama (1977) | AC | 3.4 | 0.0 | 3.4 |
| CWT | 4.8 | 0.0 | 4.8 | |
| Ledgeway and Rogers (1999) | TL | 3.9 | 0.6 | 3.3 |
| BJR | 5.8 | 1.3 | 4.5 | |
| MLG | 2.9 | 0.5 | 2.4 | |
| Siderov, Harwerth, and Bedell (1999) | AK1 | 0.56 | – | – |
| AK2 | 0.48 | – | – | |
| HB1 | 0.49 | – | – | |
| HB2 | 0.40 | – | – | |
| LB1 | 0.62 | – | – | |
| LB2 | 0.41 | – | – | |
| MG1 | 0.32 | – | – | |
| MG2 | 0.41 | – | – | |
| Grove, Kaneko, and Ono (2001) | PG | 1.9 | – | – |
| HK | 1.7 | – | – | |
| NU | 1.6 | – | – | |
| Schreiber et al. (2008) | PRM | 2.8 | 0.0 | 2.8 |
| KMS | 6.1 | 0.0 | 6.1 | |
| HRF | 3.6 | 0.0 | 3.6 |
Note: θv is the angle between the vertical meridians. θh is the angle between the horizontal meridians (cyclovergence). θr is the difference between the two, indicating the amount of retinal shear between corresponding points. All of these studies used apparent-motion except:
a
binocular apparent vertical and horizontal;
b
monocular apparent vertical. For Siderov et al. (1999):
1
viewing distance = 200 cm;
2
viewing distance = 50 cm.