[open] Pictures from blurry to clear

Donna

Hello. I'm working on my bachelor study Psychology. In the experiment we use OpenSesame. Part of the experiment is a task that tests the implicit memory about a movie. We want to let go a image from the film very slowly from blurred to sharp. The participants have to press a button when they recognize the subjects. The reaction time should then be saved as a measure.

Who can help us to program?

sebastiaan

Hi Donna,

The easy-but-time-consuming way would be to create blurred copies of your image using a graphics program (e.g. gimp).

However, you can also do the blurring automatically using an inline script, for example using the Picture.blur() method, which is part of Expyriment. The following script shows an image with various levels of blurring and halts the presentation when a key is pressed (see code for comments):

from expyriment.stimuli import Picture
from openexp.keyboard import keyboard

# Presentation duration
dur = 500

# Maximum blurring
maxBlur = 10

# Minimum blurring (1 = no blur)
minBlur = 1

# Get a picture path from the file pool
picPath = exp.get_file('armadillo.jpg')

# Create a keyboard object
my_keyboard = keyboard(exp)

# Create a list of pictures with different
# levels of blur
picList = []
# Loop from maxBlur to minBlur with decreasing steps
for blurLevel in range(maxBlur, minBlur-1, -1):
    # New picture
    pic = Picture(picPath)
    # Apply blur
    pic.blur(blurLevel)
    # Add picture to list
    picList.append(pic)

# Note the start time
t1 = self.time()

# Show all pictures!
for pic in picList:
    pic.present()
    # Wait and poll the keyboard. If a key is pressed
    # exit the loop.
    response, t2 = my_keyboard.get_key(timeout=dur)
    if response != None:
        break

# Set the response variables
response_time = t2 - t1
exp.set('response_time', response_time)
exp.set('response', response)

This requires the xpyriment back-end, as directly invokes functionality from Expyriment. For more information, see:

• http://docs.expyriment.org/expyriment.stimuli.Picture.html

Hope this helps!

Cheers,
Sebastiaan

Donna

Thanks you very much!!