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FAQ: How can I collect keyboard responses without ending the trial?
#1
In some tasks, a participant must make a keypress response, but the on-screen stimuli need to remain visible for a fixed duration on every trial. In other words, the keypress should be recorded but should not terminate the stimulus presentation.

A simple solution is to use a Keyboard Trigger to capture the response, followed by a Timer Trigger that is linked back to the stimulus onset to control the trial's duration.

Here is the recommended node sequence:
  • Display Screen: The node that presents your stimulus.
  • Keyboard Trigger: This node waits for and records the participant's keypress.
  • Intermediate Node: An action node, such as an Update Attribute (to save the response) or a Null Action, must be placed here to separate the two triggers.
  • Timer Trigger: This node will end the trial. To ensure a fixed duration, set its Start Time property to reference the start time of the initial stimulus screen (e.g., DISPLAY_SCREEN.startTime).
This structure ensures the trial's duration is always controlled by the Timer Trigger, which begins its countdown when the stimulus first appears. The Keyboard Trigger simply records a response if one is made, without affecting the overall timing.
   


Advanced Example
For a more complex task involving multiple keypresses within a single trial, please see the RECALL_SEQ sequence in the Create False Memories Example.