Experiment 1: design, behavior, and training data.

(A) Target stimulus set and schematic of the markers for the different types of processing (showing example stimuli). (B) Trial design. (C) Effects of memantine on subjective state assessed with the visual analogue scale. The categories alertness, contentedness, and calmness are based on Bond and Lader (1974), sedation on Danion et al. (1989). For details see Methods. (D) Participants’ ability to detect the Kanizsa illusion in the second target stimulus (T2). (E) Tenfold cross-validation decoding scheme applied to an independent training dataset. Mean decoding performance, area under the receiver operating characteristic curve (AUC), over time ± standard error of the mean (SEM) is shown. Thick lines differ from chance: P<0.05, cluster-based permutation test. Local contrast, collinearity, and illusion decoding accuracy peaked at 86, 242, and 273 ms after stimulus onset and these peaks were encompassed by a 78-94, 192-292, and 223-323 ms time window, respectively. Error bars are mean ± SEM. Individual data points are plotted using low contrast. Ns is not significant (P>0.05). **P=0.005.

Decoding applied to the T1 data.

(A) Local contrast, collinearity, and Kanizsa illusion decoding. These three visual features’ time windows: 78-94, 192-292, and 223-323 ms, respectively. Covariance/class separability maps with arbitrary units (AU) reflecting underlying neural sources are shown. Below these maps: mean decoding performance, area under the receiver operating characteristic curve (AUC), over time ± standard error of the mean (SEM). Thick lines differ from chance: P<0.05, cluster-based permutation test. (B) Mean AUC for every time window. Error bars are mean ± SEM. Individual data points are plotted using low contrast. Ns is not significant (P>0.05). ***P<0.001.

Decoding of the T2 data.

(A) Local contrast decoding: mean decoding performance, area under the receiver operating characteristic curve (AUC), over time ± standard error of the mean (SEM). Thick lines differ from chance: P<0.05, cluster-based permutation test. (B) Mean AUC for local contrast (rotation) decoding’s time window: 78-94 ms. Error bars are mean ± SEM. Individual data points are plotted using low contrast. Ns is not significant (P>0.05). (C) Collinearity decoding: mean AUC over time. (D) Mean AUC for collinearity decoding’s time window: 192-292 ms. (E) Kanizsa illusion decoding: mean AUC over time. (F) Mean AUC for Kanizsa illusion’s time window: 223-323 ms. *P=0.010.

Experiment 2: design, behavior, and training data.

(A) Trial design. (B) Effects of memantine on subjective state assessed with the visual analogue scale. The categories alertness, contentedness, and calmness are based on Bond and Lader (1974), sedation on Danion et al. (1989). For details see Methods. (C) Participants’ ability to detect the task-relevant feature. (D) Tenfold cross-validation decoding scheme applied to an independent training dataset. Mean decoding performance, area under the receiver operating characteristic curve (AUC), over time ± standard error of the mean (SEM) is shown. Thick lines differ from chance: P<0.05, cluster-based permutation test. Local contrast, collinearity, and illusion decoding accuracy peaked at 86, 297, and 266 ms after stimulus onset and these peaks were encompassed by a 78-94, 247-347, and 217-317 ms time window, respectively. Error bars are mean ± SEM. Individual data points are plotted using low contrast. Ns is not significant (P>0.05).

Decoding results of experiment 2.

(A) Local contrast decoding: mean decoding performance, area under the receiver operating characteristic curv e (AUC), over time ± standard error of the mean (SEM). Thick lines differ from chance: P<0.05, cluster-based permutation test. (B) Mean AUC for local contrast decoding’s time window: 78-94 ms. Error bars are mean ± SEM. Individual data points are plotted using low contrast. Ns is not significant (P>0.05). (C) Collinearity decoding: mean AUC over time. (D) Mean AUC for collinearity decoding’s time window: 217-317 ms. (E) Kanizsa illusion decoding: mean AUC over time. (F) Mean AUC for Kanizsa illusion’s time window: 223-323 ms. **P=0.002.