Add background flash with Cedrus box

Builder
1

(macOS Sequoia 15.1.1)
(PsychoPy Standalone v2024.1.4, Builder view)

Hi, thanks for the help. I have a routine where participants watch a movie and press a Cedrus button box multiple times throughout (the button press does not end the routine). I want to add a background flash behind the movie as feedback for each button press.

I tested this with a keyboard space button using the custom code component below, which worked.

Begin routine:

win.color = 'black'  # Initial background color
flash = False       # Flag to control flashing
flash_timer = 0     # Timer to track how long the flash lasts
flash_duration = 0.4  # Duration of flash in seconds (adjust as needed)

Each frame:

# Detect space bar press
theseKeys = event.getKeys(keyList=['space'])

# Initialize flash when space is pressed
if 'space' in theseKeys:
    win.color = 'Gainsboro'  # Start with white flash
    flash_stage = 1  # Stage 1: white
    flash_timer = t  # Start timing the flash

# Proceed with flash stages if flash has been initiated
if 'flash_stage' in locals():  
    if flash_stage == 1 and t - flash_timer >= 0.1:  # After 0.1s switch from white to grey
        win.color = 'grey'
        flash_stage = 2  # Move to stage 2
        flash_timer = t  # Reset timer for next stage

    elif flash_stage == 2 and t - flash_timer >= 0.1:  # After 0.1s switch from grey to black
        win.color = 'black'
        del flash_stage  # End flash sequence
        del flash_timer  # Clean up the timer

I couldn’t get this to work with the Cedrus button box. I tried adding this into Begin routine: buttonBox = cedrusBox_0, and replacing the first line of Each frame with: theseKeys = buttonBox.getKeys()

I get this error:

    return getattr(self._impl, attrname)
AttributeError: 'NoneType' object has no attribute 'getKeys'
################# Experiment ended with exit code 1 [pid:7178] #################

Any ideas about how to get this working?
Thank you!

2

How do you normally get responses from the Cedrus buttonBox?

It could be that you just need to check buttonBox exists first with if buttonBox:.