The control package of expyriment.


expyriment.control.end(goodbye_text=None, goodbye_delay=None, confirmation=False, fast_quit=None, system_exit=False, pre_quit_function=None)

End expyriment.


goodbye_text : str, optional

text to present on the screen when quitting

goodbye_delay : int, optional

period to show the goodbye_text

confirmation : bool, optional

ask for confirmation (default = False)

fast_quit : bool, optional

quit faster by hiding the screen before actually quitting (default = None)

system_exit : bool, optional

call Python’s sys.exit() method when ending expyriment (default = False)

pre_quit_function : function, optional

function to be called before quitting Pygame


out : bool

True if Expyriment (incl. Pygame) has been quit.


Check if the audiosystem is busy playing sounds.


channel : pygame.mixer.Channel, optional

specific channel to check


out : bool

Returns True if any sound is playing.

expyriment.control.get_defaults(search_str='', as_string=False)

Return a dictionary with all default values in the current Expyriment environment. The keys represent the variables names.


search_str : str, optional

search for a specific expression

as_string : bool, optional

print as string instead of dict


Initialize an experiment.

This initializes an experiment defined by ‘experiment’ as well as the underlying expyriment system. If ‘experiment’ is None, a new Experiment object will be created and returned. Furthermore, a screen, a clock, a keyboard and a event file are created and added to the experiment. The initialization screen is shown for a short delay to ensure that Python is fully initialized and time accurate. Afterwards, “Preparing experiment...” is presented on the screen.

After experiment initialize the following additional properties are available:

  • experiment.screen – the current screen
  • experiment.clock – the main clock
  • experiment.keyboard – the main keyboard
  • experiment.mouse – the main mouse
  • experiment.event – the main event file

experiment : design.Experiment, optional

the experiment to initialize


exp : design.Experiment

initialized experiment


Pause a running experiment.

This will show a pause screen and waits for ENTER to be pressed to continue.

expyriment.control.register_wait_callback_function(function, exp=None)

Register a wait callback function.

The registered wait callback function will be repetitively executed in all Expyriment wait and event loops that wait for an external input. That is, they are executed by the following functions (at least once!):

  • control.wait_end_audiosystem
  • misc.Clock.wait
  • misc.Clock.wait_seconds
  • misc.Clock.wait_minutes
  • io.Keyboard.wait
  • io.Keyboard.wait_char
  • io.Mouse.wait_press
  • io.SerialPort.read_line
  • io.StreamingButtonBox.wait
  • io.EventButtonBox.wait
  • io.GamePad.wait_press
  • io.TriggerInput.wait
  • io.TextInput.get
  • io.TouchScreenButtonBox.wait
  • io.extras.CedrusResponseDevice.wait
  • stimuli.Video.wait_frame
  • stimuli.Video.wait_end

function : function

the wait function

exp : design.Experiment, optional

specific experiment for which to register wait function


CAUTION! If wait callback function takes longer than 1 ms to process, Expyriment timing will be affected!


Run the Expyriment test suite.

expyriment.control.set_develop_mode(on=True, intensive_logging=False, skip_wait_methods=False)

Set defaults for a more convenient develop mode.


on : bool, optional

set develop_mode on (True) or off (False)

intensive_logging : bool, optional

True sets expyriment.io.defaults.event_logging=2 (default = False)

skip_wait_methods : bool, optional

If True, all wait functions in the experiment (i.e. all wait functions in expyriment.io and the clock) will be ommited (default = False)


The function set the following global variables

>>> expyriment.control.defaults.initialize_delay = 0
>>> expyriment.control.defaults.window_mode = True
>>> expyriment.control.defaults.fast_quit = True
>>> expyriment.control.defaults.auto_create_subject_id = True
>>> expyriment.io.defaults.outputfile_time_stamp = False
expyriment.control.start(experiment=None, auto_create_subject_id=None, subject_id=None, skip_ready_screen=False)

Start an experiment.

This starts an experiment defined by ‘experiment’ and asks for the subject number. When the subject number is entered and confirmed by ENTER, a data file is created. Eventually, “Ready” will be shown on the screen and the method waits for ENTER to be pressed.

After experiment start the following additional properties are available:

  • experiment.subject – the current subject id
  • experiment.data – the main data file

experiment : design.Experiment, optional (DEPRECATED)

don’t use this parameter, it only exists to keep backward compatibility

auto_create_subject_id : bool, optional

if True new subject id will be created automatically

subject_id : integer, optional

start with a specific subject_id; no subject id input mask will be presented; subject_id must be an integer; setting this paramter overrules auto_create_subject_id

skip_ready_screen : bool, optional

if True ready screen will be skipped (default=False)


exp : design.Experiment

The started experiment will be returned.


Start the audio system.


The audiosystem is automatically started when initializing an Experiment!


Stop the audio system.


Unregister all wait callback functions.


exp : design.Experiment, optional

specific experiment for which to unregister the wait callback function

expyriment.control.wait_end_audiosystem(channel=None, callback_function=None, process_control_events=True)

Wait until audiosystem has ended playing sounds.

Blocks until the audiosystem is not busy anymore and only returns then.


channel : pygame.mixer.Channel, optional

specific channel to wait for end of playing

callback_function : function, optional

function to repeatedly execute during waiting loop

process_control_events : bool, optional

process io.Keyboard.process_control_keys() and io.Mouse.process_quit_event() (default = True)


This will also by default process control events (quit and pause). Thus, keyboard events will be cleared from the cue and cannot be received by a Keyboard().check() anymore!