Different rules for binocular combination of luminance flicker in cortical and subcortical pathways
- Department of Psychology, University of York, United Kingdom
- School of Psychology and Vision Sciences, University of Leicester, United Kingdom
- York Biomedical Research Institute, University of York, United Kingdom
Figures
Figure 1
Summary of pupillometry results for N=30 participants.
Panel (a) shows a group average waveform for binocular presentation (low pass filtered at 5 Hz), with the driving signal plotted at the foot. Negative values indicate constriction relative to baseline, and positive values indicate dilation. Panel (b) shows the average Fourier spectrum (absolute amplitude values). Panels (c, d) show contrast response functions for pupil diameter at 2 Hz for different conditions (illustrated in Figure 8). Panel (e) shows contrast response functions at 1.6 Hz for three conditions. Shaded regions and error bars indicate bootstrapped standard errors.
Figure 2
Summary of EEG results for N=30 participants.
Panel (a) shows a group average waveform for binocular presentation (low pass filtered at 5 Hz), with the driving signal plotted at the foot. Panel (b) shows the average Fourier spectrum, and inset scalp distributions. Black dots on the scalp plots indicate electrodes Oz, POz, O1, and O2. Panels (c, d) show contrast response functions at 2 Hz for different conditions. Panel (e) shows contrast response functions at 1.6 Hz for three conditions. Panels (f–h) are in the same format but for the second harmonic response. Shaded regions and error bars indicate bootstrapped standard errors.
Figure 3
Ratio of binocular to monocular response for three data types.
These were calculated by dividing the binocular response by the monocular response at each contrast level, using the data underlying Figure 1c and Figure 2c, f. Each value is the average ratio across N=30 participants, and error bars indicate bootstrapped standard errors.
Figure 4
Binocular facilitation at different temporal frequencies, measured using EEG.
Panel (a) shows Fourier spectra for responses to binocular flicker at five different frequencies (offset vertically for clarity). Panel (b) shows the response at each stimulation frequency for monocular (red circles) and binocular (blue squares) presentation. Panel (c) shows the ratio of binocular to monocular responses. Error bars and shaded regions indicate bootstrapped standard errors across N=12 participants.
Figure 5
Contrast matching functions.
Dotted and dashed lines are predictions of canonical summation models involving linear combination (dotted) or a winner-take-all rule (dashed). Error bars indicate the standard error across participants (N=10), and are constrained along radial lines converging at the origin. Note that, for the 48% match, the data point on the x-axis falls higher than 100% contrast. This is because the psychometric function fits for some individuals were interpolated such that the PSE fell above 100%, shifting the mean slightly above that value.
Figure 6
Summary of computational modeling.
Panels (a–d) show empirical data from key conditions, replotted from earlier figures for the pupillometry (a), first harmonic EEG responses (b), second harmonic EEG responses (c) and contrast matching (d) experiments, with curves showing model behavior generated using the median group-level parameter values. Panel (e) shows the posterior probability distributions of the interocular suppression parameter for each of the four model fits. The pupillometry distribution (green) is centered about a substantially higher suppressive weight than for the other data types (note the logarithmic x-axis). The black curve shows the (scaled) prior distribution for the weight parameter.
Figure 7
Summary of intermodulation responses in pupillometry (a) and EEG (b) data.
The data are pooled across the binocular cross and dichoptic cross conditions of Experiment 1, with a target contrast of 48%. Vertical dashed lines indicate the fundamental flicker frequencies of 2 Hz (F1; black) and 1.6 Hz (F2; green), and the intermodulation difference (F1-F2=0.4 Hz) and sum (F1+F2=3.6 Hz) frequencies (red). Data are averaged across N=30 participants, and shaded regions indicate ±1 standard error.
Figure 8
Schematic diagram illustrating the ocular arrangements, and temporal waveforms of the luminance modulations used in Experiment 1.
Shaded waveforms indicate a target stimulus, that was presented at one of five contrasts on each trial (denoted by the shading levels). Unshaded waveforms indicate mask stimuli, that were presented at a fixed contrast level of 48% regardless of the target contrast. Each waveform corresponds to a 1 s period of a 12 s trial, and coloured symbols are for consistency with Figures 1 and 2. The icon in the upper left corner illustrates the stimulus appearance (a luminous disc against a black background). The left and right eye assignments were counterbalanced across trials in the experiment (i.e. the monocular stimulus could be shown to either eye with equal probability).
Appendix 1—figure 1
Summary of pupillometry results for N=12 participants, for peripheral stimulation.
See Figure 1 for a description of each panel.
Appendix 1—figure 2
Summary of steady-state EEG results for N=12 participants, for peripheral stimulation.
See Figure 2 for a description of each panel.
Author response image 1
Tables
Table 1
Summary of median parameter values.
| Dataset | Z | n | w | Rmax |
|---|---|---|---|---|
| Pupillometry | 3.44 | 0.01 | 0.61 | 0.00023 |
| EEG 1 F | 2.62 | 0.15 | 0.02 | 0.00336 |
| EEG 2 F | 3.71 | 0.07 | 0.02 | 0.0031 |
| Matching | 0.30 | 5.10 | 0.09 | - |
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Different rules for binocular combination of luminance flicker in cortical and subcortical pathways
eLife 12:RP87048.
https://doi.org/10.7554/eLife.87048.3
