Trials timeline

The trials timeline (Figure 1) provides a temporal view of the trial and editing of logical order, style and timing of each construct within the trial. Each item on the timeline contains annotations describing its temporal properties and hovering the mouse pointer over these annotations will display a full rundown of the timing properties for the construct.

Figure 1. Timeline editor

Adding a construct

You can add constructs to the trial timeline by clicking on New item. When creating a new construct, you can choose to start with a blank slate, to copy an existing construct from this or another trial, or to clone an existing construct from another trial.

Cloning is an important part of response button position randomization and response keyboard key value randomization across multiple trial blocks.

Editing construct timing properties

Click anywhere along its row on the timeline to open the editor:

  • Start mode
    • Fixed: start time will be measured from the beginning of the trials timeline.
    • Offset from previous item: start time will be measured from the end of the previous item on the trials timeline. If there is no previous item, or the timeout of the previous item is set to nil(infinite), then start time will be measured from the beginning of the trial.
  • Start time (ms): when to initiate construct.
  • Duration mode
    • Fixed: duration will be a fixed time period.
    • Random: duration will be a random time period bound by minimum and maximum values.
    • Factor: duration will be a randomly chosen level from the factor selected.
    • Level: duration will be set to the value of the chosen level.
  • Timeout (ms): duration of construct presence.

Editing a construct

Click anywhere along its row (Figure 2) to open the editor.

Figure 2. Open construct editor

Timing and (if applicable) visual style properties can be edited from this view. For details on a specific construct please see the documentation for that construct.

Removing a construct

Constructs can be removed from the trial timeline by clicking on Delete next to the construct.

WARNING: Deleting a construct will also remove any trials rules related to that construct.

Reordering constructs

The logical order of constructs can be changed by dragging and dropping within the timeline. The temporal order will only change if any affected construct has a start mode set to Offset from previous item.

Setting stimulus cycles

Click on Stimulus cycles: 1 to set how many times all stimuli are presented. For example, if there are 10 stimuli in total and number of cycles is set to 3, there will be 30 stimuli presented in total (and therefore, 30 trials in this trial block).

Setting stimulus selection strategy

Stimulus selection: random determines how stimuli will be selected for each trial.

  • Sequential: selects stimuli for each trial in order.
  • Random: fully randomize stimuli across all cycles. Any single stimulus may appear zero, one or many times in any given cycle. Each stimulus will be presented an equal number of times as cycles selected. In the case of a single cycle, Random is no different to Random within cycle.
  • Random within cycle: randomize stimuli within each cycle only. Any single stimulus will appear exactly once in any given cycle.

Setting the stimulus set

Click on Stimulus set: nil to select the stimulus set for these trials to operate on. You may also create a new set here as well as clear the current set.

WARNING: Changing or clearing the current stimulus set will also remove:

Managing stimuli

The stimulus manager for the currently selected stimulus set can be accessed by clicking Stimulus manager.... Alternatively, you can manage a stimulus set by clicking on the Stimuli tab and selecting the desired set from the drop-down list (Figure 3).

Figure 3. Stimulus set selection