Table 2.
Comparison of average VEP SF limits and psychophysical thresholds in normally sighted adults using identical stimuli (see Fig. 5a)
| Study | Number of subjects | VEP stimulus | VEP SF limit (cpd) | Psychophysical threshold (cpd) | VEP minus psychophysical difference (log units) | VEP method | Psychophysical method |
|---|---|---|---|---|---|---|---|
| #54 [88] | 16 | Vertical sinusoidal gratings, 80%, 80 cd m−2, 15 rps, coarse-to-fine | 37.5 | 35.1 | − 0.029 | Monocular, Oz–O1/O2, DFT, linear extrapolation of magnitude to 0 μV | Monocular, method of ascending and descending limits, button press to indicate grating appearance/disappearance, geometric mean of 5 trials |
| as above but fine-to-coarse | 36.3 | 33.3 | − 0.038 | ||||
| #326 [36] | 16 | Horizontal sinusoidal gratings, 90%, 50 cd m−2, 15 rps, coarse-to-fine | 38.7 (SEM 1.2) | 42.4 (SEM 1.2) | 0.039 | Binocular, 5 occipital channels, DFT, linear extrapolation of magnitude to 0 μV | Temporal, 2-alternative forced-choice, 2-down, 1-up staircase, last 10 measurements for threshold: 77% correct |
| #88 [20] | 10 | Vertical sinusoidal gratings, 40%, 40 cd m−2, 12 or 7.5 rps, 2 × 3° |
26.1 (mag) 32.7 (phase) |
42.5 |
0.212 0.114 |
Oz–RO/LO, DFT, linear extrapolation of magnitude or phase versus SF to noise floor | Simultaneous button press at end of each VEP trial if a grating was seen; 50% threshold |
| #46 [116] | 8 | Monocular, vertical and horizontal sinusoidal gratings, 86%, 50 cd m−2, 7 rps, 2 × 3° | 25 | 26.3 | 0.022 | Oz–earlobe, sweep, linear extrapolation of amplitude to amplifier baseline | Verbal indication when moving sensation first occurred; method of adjustment, average of 2 ascending and 2 descending limits |
| #89 [32] | 7; 10 | Vertical sinusoidal gratings, 80%, 220 cd m−2, 12 rps, 14 × 28 cm | 31.9 | 29 | − 0.041 | Oz–O1/O2, DFT, linear extrapolation of magnitude to 0 μV | Psychophysical CS function including 80%; ascending and descending limits, button push at threshold |
| #150 [22] | 6 | Horizontal sinusoidal gratings, 40%, 50 cd m−2, 15 rps, 6.3 × 6° | 33.5 (SD 4.5) | 42.5 (SD 2.6) | 0.103 | Oz–Cz, adaptive filter, linear extrapolation of magnitude to 0 μV (automated, “C0”) | 2-alternative FC staircase, 2-down, 1-up, converge to 82% threshold, 35–60 cpd, step size 1/10 of range |
| #178 [14] | 4 | Vertical sinusoidal gratings, 80%, 0.1 cd m−2, 12 rps, @ 80 cm | 2.8 | 4.2 | 0.176 | Oz–lateral, DFT, linear extrapolation of magnitude to 0 μV | Forced-choice 2-alternative technique using same stimulus at 80 cm, 3–5 SFs, 75% correct |
| as above but 100 cd m−2 | 25 | 50 | 0.301 | ||||
| #160 [29] | 1 | Vertical sinusoidal gratings, 80%, 46 cd m−2, 24 rps, 20 × 15° | 11.3 | 14.6 | 0.111 | Oz–lateral, synchronous filter, linear extrapolation of relative amplitude to 0 μV | Psychophysical version of VEP stimulus, methods of adjustment, observer adjusted SF until threshold × 3 |
| as above but square-wave gratings, 90%, 360 cd m−2, 2 × 2° | 31 | 32 | 0.014 | ||||
| #1 [105] | not stated | Red (lit) and black (off) 14 × 7 photodiode checkerboard, 2 rps, 36 × 18 mm | ≈ 3.2 | ≈ 7.05 or ≈ 10.2 | 0.349 or 0.503 | Iz–mastoid, objective time domain analysis, distance at which VEP not significant | Subjects indicate the distance from which the checkerboard phase reversal is no longer perceived |
Hashtag numbers indicate the 155 references whose data were included in the systematic review