Mean reaction times (RTs), time-to-peaks (TTPs), peak response forces (PFs), and standard errors of means (± SEM) for correct and incorrect responses as a function of Target Force (low, high) and Target TTP (short, long).

1<p>including errors of the opposite force and errors of the not-opposite force;</p><p>²including errors of the opposite and errors of the not-opposite TTP.</p

The force-unit monitoring model.

<p>Simulated data. (A) Two gamma functions with the same peak amplitude representing the force-unit activation for the short TTP (FU1) and the long TTP (FU2) condition. (B) The resulting function from the summation of the two 33 and 50 FU functions, representing the low and high target-force conditions and the short and long target-TTP conditions. (C) Two gamma functions with the same area under the curve representing the monitoring unit activation for the short TTP (MU1) and the long TTP (MU2) condition. (D) The resulting functions from the summation of the two 33 and 50 MU functions. Empirical data. (E) Mean force-time curves, time-locked to the response onset (0 ms) as a function of target force and target TTP. (F) Grand average waveforms of event-related potentials as a function of target TTP and target force.</p

Visual feedback of the force-time diagrams.

<p>(A) Force-time diagrams of the first practice trials including the target-force ranges (shaded areas) for 20% and 45% of MVF (upper panels) and target-TTP ranges for 150 ms and 400 ms (lower panels). A correct and an incorrect response, as well as an insufficient, excluded force pulse, are depicted. (B) Force-time diagrams for the four experimental conditions obtained by the combinations of the two target-force and the two target-TTP ranges.</p

Grand average ERP waveforms and current density maps.

<p>(A) Grand average waveforms of event-related potentials at the FCz electrode site, time-locked to response onset, as a function of target TTP and Response Type (including all error types). Waveforms are shown separately for the low force condition (left panel) and high force condition (right panel). (B) Current-source density maps show the general scalp distribution of cortical activity of the correct responses separately for target forces (low, high) and target TTPs (short, long) in an interval from 50 ms to 500 ms after response onset.</p

Grand average ERP waveforms for correct responses and errors of force selection.

<p>Grand average waveforms of event-related potentials at the FCz electrode site, (A) time-locked to response onset for (left panel) correct responses and errors of the opposite force and (right panel) for correct responses and errors of the opposite TTP, (B) time-locked to TTP onset for (left panel) correct responses and errors of the opposite force and (right panel) for correct responses and errors of the opposite TTP.</p

Mean response rates and standard errors of means (± SEM) of correct and incorrect responses as a function of Target Force (low, high) and Target TTP (short, long).

<p>Note: The values do not add up to 100% because of the excluded responses (i.e., no response and no isometric force pulses);</p>1<p>Ranges of the percentage of the four combined TTP-Force error types (e.g., too weak and too short).</p

SVR results for arousal ratings.

<p>A) Spatio-temporal decoding: Multivariate support vector regression (SVR) was used to regress <i>arousal</i> ratings (in increments: low/medium/high) from distributed patterns of CSD-ERPs within analysis time windows of 40 ms that were moved through the first 500 ms of each trial in steps of 20 ms. Ratings could be regressed significantly above chance between 180–200 ms (denoting the central time points of the analysis windows) and again around 380 ms after stimulus presentation (black line). Additionally shown are the results of the same SVR analysis using shuffled labels to obtain an empirical chance distribution for statistical testing (grey line). B) Temporal decoding: Multivariate SVR was used for each channel separately to regress <i>arousal</i> ratings (in increments: low/medium/high) from purely temporal patterns of CSD-ERPs within the first significant time period of the spatio-temporal analysis (combined time bins 180 ms and 200 ms). The heat map illustrates predictive channels, with electrodes P9 (<i>t</i>(14) = 2.59*), PO3 (<i>t</i>(14) = 2.24*), O1 (<i>t</i>(14) = 2.46*), P6 (<i>t</i>(14) = 2.46*), PO4 (<i>t</i>(14) = 2.87*) reaching significance. *<i>P</i><.05; **<i>P</i><.01 (uncorrected); error bars  =  standard errors.</p

Scalp distributions of differences in CSD-ERPs.

<p>The left column displays scalp maps for the average distribution of voltage for the N1 (50 to 150 ms), the N2 (150–250 ms), the EPN (280 to 320 ms) and the P3 (300 to 700 ms) time windows. The middle column visualises the difference maps for <i>arousal</i> (high minus low), and the right column displays the difference maps for <i>time reference</i> (future minus present) for the same ERP components.</p

Correlation coefficients of Low-level Image Features and Ratings.

<p>Note: <i>r</i> =  Pearson correlation coefficients; <i>P</i> =  uncorrected significance level; SD  =  Standard Deviation of the Mean; ‘Mean ratings’ refers to tests between the average ratings (across all participants) and the low-level image feature parameters; ‘Individual ratings’ refers to the averaged correlation coefficients between the individual participants' ratings and the low-level image features (SE  =  Standard Error of the Mean; Mean <i>r</i>_z  =  Fisher-Z-transformed <i>r</i>; *the critical value for <i>P</i><.05, df  = 23) was <i>r</i>_crit  = .553.</p><p>Correlation coefficients of Low-level Image Features and Ratings.</p

Means, standard errors of mean, and ANOVA results for the components of the event-related potentials for <i>arousal</i> ratings.

<p>Note: <i>df</i>s Greenhouse-Geisser corrected if required; SE  =  standard error of mean; **<i>P</i><.01.</p><p>Means, standard errors of mean, and ANOVA results for the components of the event-related potentials for <i>arousal</i> ratings.</p