Keyboard¶

Psychtoolbox versus event.getKeys¶

On 64 bits Python3 installations it provides access to the Psychtoolbox kbQueue series of functions using the same compiled C code (available in python-psychtoolbox lib).

On 32 bit installations and Python2 it reverts to the older psychopy.event.getKeys() calls.

The new calls have several advantages:

• the polling is performed and timestamped asynchronously with the main thread so that times relate to when the key was pressed, not when the call was made

• the polling is direct to the USB HID library in C, which is faster than waiting for the operating system to poll and interpret those same packets

• we also detect the KeyUp events and therefore provide the option of returning keypress duration

• on Linux and Mac you can also distinguish between different keyboard devices (see getKeyboards())

This library makes use, where possible of the same low-level asynchronous hardware polling as in Psychtoolbox

Example usage

from psychopy.hardware import keyboard
from psychopy import core

kb = keyboard.Keyboard()

# during your trial
kb.clock.reset()  # when you want to start the timer from
keys = kb.getKeys(['right', 'left', 'quit'], waitRelease=True)
if 'quit' in keys:
    core.quit()
for key in keys:
    print(key.name, key.rt, key.duration)

Classes and functions¶

class psychopy.hardware.keyboard.Keyboard(deviceName=None, device=-1, bufferSize=10000, waitForStart=False, clock=None, backend=None)[source]¶

getState(keys)[source]¶

Get the current state of a key or set of keys

Parameters:

keys (str or list[str]) – Either the code for a single key, or a list of key codes.

Returns:

keys – True if pressed, False if not. Will be a single value if given a single key, or a list of bools if given a list of keys.

Return type:

bool or list[bool]

class psychopy.hardware.keyboard.KeyPress(code, tDown, name=None)[source]¶

Class to store key presses, as returned by Keyboard.getKeys()

Unlike keypresses from the old event.getKeys() which returned a list of strings (the names of the keys) we now return several attributes for each key:

.name: the name as a string (matching the previous pyglet name) .rt: the reaction time (relative to last clock reset) .tDown: the time the key went down in absolute time .duration: the duration of the keypress (or None if not released)

Although the keypresses are a class they will test ==, != and in based on their name. So you can still do:

kb = KeyBoard()
# wait for keypresses here
keys = kb.getKeys()
for thisKey in keys:
    if thisKey=='q':  # it is equivalent to the string 'q'
        core.quit()
    else:
        print(thisKey.name, thisKey.tDown, thisKey.rt)

psychopy.hardware.keyboard.getKeyboards()[source]¶

Get info about the available keyboards.

Only really useful on Mac/Linux because on these the info can be used to select a particular physical device when calling Keyboard. On Win this function does return information correctly but the :class:Keyboard can’t make use of it.

Returns:

USB Info including with name, manufacturer, id, etc for each device

Return type:

A list of dicts