Post-hoc simulations.

<p>Results for post-hoc simulations: Exp Full: the experiment using the full number of probes, Exp: results from the experiment with early stopping, Sim: simulation results with early stopping, Rand Sim: simulation with random probe selection and early stopping, Sim 150×10k: simulation with 150 targets and 10.000 probes with early stopping, Sim 10k×10k: simulation with 10.000 targets and 10.000 probes with early stopping. Top-left: Proportion correct, related correct and in top 10. Top-right: Rank, the rank for the last analysis (Sim 10k×10k) is scaled by dividing by 61.8. Bottom-left: Number of probes. Bottom-right: Information Transfer Rate. * indicates .001 < p <.05, ** indicates p <.001.</p

Association strength.

<p>Average association strength per block. The error bars indicate the standard deviation.</p

Classification accuracies.

<p>Single trial classification accuracies, based on relatedness labels from the Leuven dataset. All classification accuracies differ significantly from chance level (0.5) with a p-value of <.001.</p

Grand Average TFR.

<p>Grand average TFR results for the training block for channel C3. The data shown here is a normalised difference between the related and unrelated conditions, obtained by . The grey box indicates in which parts of the figure the difference between the two conditions is significant. The vertical dashed line indicates the grand average reaction time, i.e., when the subjects pressed the button.</p

Number of associations.

<p>Number of associations for prime words in the test blocks.</p

Performace scaling.

<p>Scaling of the performance of the BCI with larger vocabularies. The vocabulary size is plotted on the x-axis. The simulation results are indicated by the black circles. A fit of the data is displayed with a dashed red line. Top-left: results for proportion correct, the data were fitted with a logarithmic function. Top-right-panel: simulation rank, the data were fitted with a power law function. Bottom-left: number of probes, data were fitted with a logarithmic function. Bottom-right: Information Transfer Rate (ITR), the data were fitted with a second order polynomial after a log transformation, peaking at a vocabulary size of 1214.</p

Design.

<p>Basic design of the experiment.</p

Decoding results.

<p>First two columns indicate proportion correct, last column indicates the number of probes used to obtain the accuracy for the <i>stop</i> condition, for the <i>full condition</i> this is always 100. Asterisks indicate whether the proportion correct differs significantly from chance level (1/150, 0.00667). * indicates .001 < p <.05, ** indicates p <.001.</p

The BCI cycle.

<p>A general framework of BCIs, showing the consecutive steps in signal processing. These steps involve stimulation in a specific modality, data measurement and pre-processing, data analysis, and output or feedback generated by the BCI. Adapted from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133797#pone.0133797.ref001" target="_blank">1</a>].</p

Free-spelling performance.

<p>Performance rates of all individual participants and the grand average during free-spelling. The table lists the total number of K trials (i.e., including backspaces), total number of K’ spelled symbols at the end of the session, number of C correctly spelled symbols, the average time T needed for spelling one symbol (including overhead: inter-trial time), and an estimate of Symbols Per Minute (SPM). Note that only early-stopping was applied, which was trained with a fixed targeted accuracy of 95 percent for all participants. Note that C is an informal measure of correctness.</p