Inquisit provides a number of commands for controlling the timing of various segments of a trial. A trial can be thought of as a sequence of four segments, illustrated in the following diagram:
| pretrialpause | Pauses for the specified duration at the begining of a trial, prior to stimulus presentation. In addition to providing a general means of controlling inter-trial intervals, the PretrialPause is useful for experiments that present large numbers of memory intensive stimuli on a given trial. Depending on the size of the stimuli and the speed of the hardware, stimulus preparation may add notable lengths of time to the beginning of the trial. Furthermore, stimulus preparation time may vary from trial to trial, in which case varying durations may be added to the beginning of the trials. However, if a PretrialPause interval is specified, Inquisit uses this time to prepare the stimulus presentation sequence. By specifying a PretrialPause duration long enough for stimulus preparation to complete, the experimenter can impose a constant and predictable duration at the beginning of each trial. |
| numframes | Specifies the number of stimulus presentations frames. A frame corresponds to a single vertical retrace interval of the monitor. |
| response | By setting this attribute to a timeout procedure (e.g., /response = timeout(1000)), it specifies the maximum duration for Inquisit to wait for the subject to respond. If no response occurs during within this duration, Inquisit finishes up the trial, waits for the postrialpause to complete, and moves onto the next. |
| timeout | Specifies the maximum duration of a trial, from the very beginning of the trial to the end, not including the posttrialpause. |
| posttrialpause | Pauses for the specified duration at the end of each trial after the subject has responded. In addition to providing a general means of controlling inter-trial intervals, the PosttrialPause is useful for experiments that present large numbers of memory intensive stimuli on a given trial. Depending on the size of the stimuli and the speed of the hardware, the process of cleaning up a stimulus presentation sequence (i.e., removing stimuli from memory) may add notable lengths of time to the end of the trial. Furthermore, stimulus cleanup time may vary from trial to trial, in which case varying durations may be added to the ends of the trials. However, if a PosttrialPause interval is specified, Inquisit uses this time to cleanup the stimulus presentation sequence. By specifying a PosttrialPause duration long enough for stimulus cleanup to complete, the experimenter can impose a constant and predictable duration at the end of each trial. |
| trialduration | Specifies the absolute duration of a trial, from beginning to end, including the posttrialpause. If the subject responds quickly, the posttrialpause interval is lengthened to fill out the remaining time in the duration. If the subject does not respond before the duration, the trial is terminated and the next trial begins. |