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pretrialsignal attribute

The pretrialsignal attribute specifies that before running a trial, Inquisit should wait for a signal from an external device.

Member of

<likert> <openended> <trial>

Syntax

/ pretrialsignal = (modality, signal)

Parameters

modality One of the following values:
Value Description
keyboard The signal is defined as a key-press on the computer’s keyboard.
com<n> The signal is defined a serial port signal, where n specifies the port number (e.g., COM1, COM2, COM3, ...).
xid<n> The signal is defined as a XID protocol signal from a Cedrus Response Box on the serial port, where n specifies the port number (e.g., XID1, XID2, XID3, ...).
lpt<n> The signal is defined as a parallel port signal, where n specifies the port number (e.g., LPT1, LPT2, LPT3, ...).
signal An integer representing the numeric signal to wait for. If the modality is keyboard, this is the scancode of the key.

Remarks

This is useful for requiring a confirmation response from subjects before starting a trial, or for synchronizing Inquisit with an external device such as an EEG.

Examples

The following trial waits for a parallel port signal of value 1 sent from an fMRI imaging system before starting the trial:

<trial target>
/ stimulusframes = [1=facepicture]
/ validresponse = (57)
/ pretrialsignal = (LPT1, 1)
</trial>

The following trial requires the subject to press the spacebar to start the trial:

<trial mytrial>
/ stimulusframes = [1=sometext]
/ validresponse = (57)
/ pretrialsignal = (keyboard, 57)
</trial>

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