Respond after the clip ends

Play an audio clip and only accept the keypress once playback has finished, with RT measured from the end of the clip.

When to use it

Use this for auditory judgements where the reaction time should measure the decision, not the listening. If responses stay open during playback, RT is counted from clip onset, so longer clips mechanically inflate the numbers and eager participants answer before they have heard the evidence. Holding the response until playback ends makes RTs comparable across clips of different lengths. If early responses are themselves the phenomenon, as in gating or interruption paradigms, leave the window open during playback instead.

Trial file

type	content	stimFormat	stim1	responseWindow	keyboard	key	button1
instructions	Listen to each clip. When it ends press F if the speaker sounds happy or J if they sound sad.						NEXT
test		.mp3	voice_happy1	afterStim	f j	f
test		.mp3	voice_sad1	afterStim	f j	j
test		.mp3	voice_happy2	afterStim	f j	f
test		.mp3	voice_sad2	afterStim	f j	j

How it works

stimFormat set to .mp3 makes each row an audio trial: the cell holds the extension, stim1 holds the basename, and the file plays as the trial’s stimulus. There is no presTime because it does not limit media playback anyway; the playback length comes from the file itself.

responseWindow set to afterStim is the timing lever. On audio and video trials the window opens after playback ends (on image trials it would instead need a presTime to take the stimulus off screen). Until the window opens, the keyboard keys are inert, so a participant cannot answer halfway through the clip, and reaction time is counted from the moment the window opens, which here means from clip end. That makes the recorded RT a clean decision time rather than clip length plus decision time.

keyboard lists the two valid keys (f j, keys are case-insensitive and any separator works) and key names the correct one, scored into the correct results column. Write key values in lowercase, because a response that matches the key only after ignoring case is recorded as unscored rather than incorrect.

One caution carries the whole recipe: responseWindow start positions are case-sensitive. afterstim is not a recognised position, and an unrecognised position means the window never opens, so the trial silently collects nothing. Also expect the automatic “enable media autoplay” screen at the start of the run; any project containing media inserts it.

Variations

• Add a deadline that starts at clip end by writing afterStim_3000 in responseWindow; with no response within 3000 ms the trial records timeout and auto-advances.
• Play two clips per trial by filling stim2 and adding an ISI gap in milliseconds; the files play in sequence and afterStim waits for the last one to finish.
• Shuffle the clip order by adding random with 1 on the test rows, leaving the instructions row’s cell empty so it stays first.
• Let participants answer during playback instead by clearing responseWindow; the window then opens at stimulus onset and RT is measured from the start of the clip.