Timing diagnostics

The trial file requests durations; the participant’s display delivers them in whole monitor frames. For each timing column you use, the results record what actually happened, in three columns each:

• _ms: the measured duration in milliseconds.
• _f: the frames drawn during the interval (semicolon-separated per screen).
• _fDuration: the mean duration of one frame in milliseconds during the interval (about 16.7 on a 60 Hz display).

Columns	Measured interval
presTime_ms, presTime_f, presTime_fDuration	How long the stimuli were actually presented, per screen, for trials using presTime.
ISI_ms, ISI_f, ISI_fDuration	The actual inter-stimulus interval, for trials using ISI.
ITI_ms, ITI_f, ITI_fDuration	The actual inter-trial interval, for trials using ITI.

Cells show na on trials where the corresponding trial-file column was not used.

Note

Small deviations between the requested and measured durations are normal: displays can only change content on frame boundaries, and a busy participant machine can drop frames. Use these columns to quantify that precision, and to exclude trials where timing mattered and deviated too far.