>Psychtoolbox>PsychBasic

[secs, keyCode, deltaSecs] = KbPressWait([deviceNumber][, untilTime=inf][, more optional args for KbWait]);

KbPressWait waits for a single key press of your subject, ie. it waits
until all keys on the keyboard are released, after that it waits for a
a press of a key, then it returns the keyboard state and timestamp of the key
press *without* waiting for the key press to finish ie, without waiting for
a key release.

It also returns if the optional deadline ‘untilTime’ is reached.

This is a convenience wrapper, doing the same thing as
KbWait(deviceNumber, 2, …); so read “help KbWait” for details about
operation and returned values.

You’ll typically use this function to ask your subject for a response and
you want to continue your script immediately without delay, even if the
subject keeps the key pressed for a while – a typical usage would be if
you want to change the stimulus immediately after response, eg, blank the
display etc.

See also: KbPressWait, KbReleaseWait, KbWait, KbCheck, KbStrokeWait.