Subjective awareness rating

After each trial, the participants were asked to verbally report their level of subjective awareness of a target that they may or may not have seen in the masked field. Awareness ratings were verbally reported according to the 4-point Perceptual Awareness Scale (Ramsøy and Overgaard 2004). Participants were provided with the following written descriptions: 1—“No experience”, 2—“Brief glimpse”, 3—“Almost clear experience”, 4—“Clear experience”. The verbal responses were recorded via a keypress by the experimenter.

Due to the low target luminance contrasts applied, there were few responses in the upper PAS categories (3 and 4) across all experiments. Therefore, all responses that were indicative of any level of awareness of targets under the masked condition (PAS score > 1) were clustered into one category of “Aware” responses and all responses with a PAS score of 1 were categorised as “Unaware” in the analysis for each experiment separately. For each condition and experiment, the number and proportion of aware and unaware responses and missed trials are reported. The frequency of each PAS response is also reported for each experiment. In the Linear Mixed Effect Model analysis, where all the data from the three experiments is combined in one analysis, the PAS responses are entered in the four-point scale (see Fig. 6a, b).

a Model plotted with the marginal effects values predicted with the function ggpredict() in the package ggeffects (Lüdecke 2018). The predictions of the model are shown together with the datapoints from all three experiments split by PAS response (1, 2, 3, 4) and the number of targets. b The marginal effects of model prediction without the data plotted over the prediction lines. Both figures were made in R with the package ggplot2 (Wickham 2016) as a part of the Tidyverse package (Wickham et al. 2019). The error margins represent the 95% CI as predicted for the model