A trial consists of one or more procedures. Each procedure consists of a timeline which in turn contains one or more constructs (aka items). As shown in (Figure 1),
Procedure 1 has a timeline containing constructs with the following items:
ISI: an Interstimulus interval construct
Fixation: a fixation construct
Color: a stimulus construct
Keys: a keyboard construct
Feedback: a feedback construct
The trials timeline (Figure 1) provides a temporal view of the trial and its procedures, and editing of logical order, style and timing of each construct within the trial. Each item on a procedure 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.
Procedure counterbalancing and counterbalancing of items within those procedures can also be managed.
A trial procedure consists of a timeline containing one or more constructs. Procedures end when an event occurs (e.g. a timeout, button click, key press, etc.) and execution of the trial either moves on to the next procedure in the trial (if there are more procedures to execute and the event action is set to move to the next procedure) or on to the next trial. Multiple procedures within a trial can be used to create things such as multi-event, multi-response trials and temporally counterbalanced stimuli (including counterbalanced compound stimuli).
Procedures can be used to produce complex experiment designs including multi-timeline, multi-stimulus, multi-response and multi-event trials with spatial counterbalancing and temporal counterbalancing. Combined with Psychstudio's rich stimulus management, response randomization and block counterbalancing, you've got world's-best trial sequencing, and stimulus/response composition and presentation. And don't forget, no code!
Click Procedure 1 and select
Create new procedure... from the timeline procedure menu (Figure 2).
Click Procedure 1 and select a procedure from the
Existing procedures in the timeline procedure menu (Figure 2).
Click Procedure 1 and select
Counterbalance procedures... from the timeline procedure menu (Figure 2).
You can add constructs to a procedure 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.
Click anywhere along its row on the timeline to open the editor:
Fixed: start time will be measured from the beginning of the procedure timeline.
Offset from previous item: start time will be measured from the end of the previous item on the procedure 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 procedure.
Click anywhere along its row (Figure 4) to open the editor.
Constructs can be removed from a procedure 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.
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).
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,
Randomis 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.
Click on Stimulus set: nil to select the stimulus set for these trials to operate on.WARNING: Changing or clearing the current stimulus set will also remove:
Stimulus sets containing compound components can be customized for a single trial set. Partial re-composition of compound stimulus sets allows you to recompose a subset of compound items isolated to this trial set only.
The customize screen (Figure 6) provides the following options:
Component: the component to partially recompose
Number of stimuli to recompose: the number of stimuli to recompose from the component
Force new compositions?: Forces new compositions; preventing any previous compositions being randomly generated. This type of forcing will always produce unique and previously unseen compositions (thus new compound stimuli) and therefore is not purely random
This kind of re-composition strategy might be handy when using the same stimulus set for practice and test. For example, a paired associate task where you're testing participants on their ability to recognize seen/unseen associations.