Perturbations Table

Four types of unit-amplitude perturbation waveforms are implemented: sinusoids, trapezoidal pulses, uniform random noise, and Gaussian noise.To apply a perturbation to the trajectory of a trial target, the perturbation waveform object -- which is displayed and modified on the Perturbations Editor -- must be attached to the trial's definition via the Perturbations Table, located on the Perturbations/RVs tab pane at the top of the Trial Editor. To do so, right-click on the leftmost column of the table. As shown in the screenshot on the right, a context menu appears. Select the command Add Perturbation. Maestro will then display a popup list of all perturbation objects currently defined under the Perturbations subtree in the open experiment document. Double-click on your choice in this list. The popup is extinguished and a new row appears in the table for the perturbation waveform you selected. Set the remaining parameters in the table appropriately:

• • The Gain column reflects the amplitude of the perturbation applied in this trial. It is a floating-point value in the range [-999.99 ... 999.99]; the default value is 1.0. Effective units are degrees/second for perturbation of a velocity component, or degrees for perturbing the direction of a velocity vector. To change the gain, you can right-click on the cell to increment the value; with the Shift key depressed, a right-click will decrement the value. Alternatively, double-click on the cell to invoke an "in-place" edit control that "covers" the cell and accepts numeric input; simply type in the new amplitude and press Enter or click somewhere outside the edit window.

  • The Seg column holds the index of the segment at which the perturbation will begin. Note that the perturbation can continue beyond the end of the specified segment, stopping after the duration specified in its definition, or at trial's end, whichever comes first. Right-click on the cell to increment the index, Shift-right-click to decrement it, or double-click on the cell to invoke an "in-place" combo box control that lets you choose a valid segment index. [Remember that Maestro will automatically revise the segment indices in this table whenever you insert a segment into or remove a segment from the trial's segment table.] If the segment index is set to NONE, then the perturbation is effectively ignored.

  • The Target column displays the name of the trial target affected by the perturbation. Right-click or Shift-right-click to cycle the value through the list of targets participating in the trial, or double-click on the cell to select a target from the dropdown list of a combo box. If NONE is selected, then the perturbation is effectively ignored.

  • The Affected column indicates what aspect of the target's trajectory is perturbed: the horizontal window velocity component (winH), the vertical window velocity (winV), the horizontal pattern velocity (patH), the vertical pattern velocity (patV), the direction of the target window velocity vector (winDir), the direction of the target pattern velocity vector (patDir), the speed (amplitude) of the target window velocity vector (winSpd), the speed of the target pattern velocity vector (patSpd). One can also choose to simultaneously perturb the speed of both window AND pattern motion with the same waveform (speed), or simultaneously perturb the direction of window and pattern motion (direc).

To remove any perturbation from the table, right-click on its name in the Pert Name column and choose Remove from the context menu. To clear the perturbation list and start from scratch, invoke the context menu and select Clear Perturbation List.