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

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

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

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

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

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