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
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.
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:
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