Use keyboard components instead of event.getKeys()
The keyboard component in PsychoPy Builder uses the Keyboard class, which has better timing than the older event module. If you want to identify whether a key has been pressed in Each Frame then code of the form
keys = event.getKeys()
can be replaced with
keys = []
if key_resp.keys: # Keyboard component should store all keys and not force the end of the routine
if len(key_resp.keys) > nKeys: # Add nKeys = 0 in Begin Routine
keys = [key_resp.keys[-1]] # keys must be a list
nKeys = len(key_resp.keys)
In both cases the code can be followed by:
if len(keys):
if 'return' in keys and len(displayText)>1: # Ensures something has been typed
continueRoutine=False
elif 'space' in keys:
displayText += ' '
elif 'backspace' in keys: # Doesn't work online
displayText=displayText[:-1]
elif 'N/A' in keys: # Several keys return N/A online
displayText=displayText[:-1]
elif 'comma' in keys:
displayText += ','
elif 'semicolon' in keys:
displayText += ';'
elif 'period' in keys:
displayText += '.'
elif 'minus' in keys:
displayText += '-'
elif 'equal' in keys:
displayText += '='
elif 'bracketleft' in keys:
displayText += '['
elif 'bracketright' in keys:
displayText += ']'
elif 'lshift' in keys or 'rshift' in keys:
modify = True # Capitalise the next letter
elif modify==False:
displayText += keys[0]
else:
if '1' in keys:
displayText += '!'
elif '2' in keys:
displayText += '\"'
elif '3' in keys:
displayText += '£'
elif '4' in keys:
displayText += '$'
elif '5' in keys:
displayText += '%'
elif '6' in keys:
displayText += '^'
elif '7' in keys:
displayText += '&'
elif '8' in keys:
displayText += '*'
elif '9' in keys:
displayText += '('
elif '0' in keys:
displayText += ')'
elif 'minus' in keys:
displayText += '_'
elif 'equal' in keys:
displayText += '+'
else:
displayText += keys[0].upper()
modify = False
This code requires the following in Begin Routine
nKeys = 0
displayText = ''
In cases where the Keyboard class is insufficient for your needs, an editable textbox using the following code might help. However, it fails if participants move their cursor away from the end of the string using the left arrow key.
if len(textbox.text) > nKeys:
keys = textbox.text[-1] # keys doesn't need to be a list because it can only have one character
elif len(textbox.text) < nKeys:
pass # Add code here if you want to register that backspace has been pressed
nKeys = len(textbox.text)
One final note. on today’s tip. If you are unable to run a simple experiment that has a keyboard component, try changing the keyboard backend in Experiment Settings / Input. There seem to be some compatibility issues with ioHub which are fixed by switching to PsychToolbox.
