To get to the point, I have amended 120 different colour TextStim (different coloured word) items to a list called 'trials'. I will be looping through 'trials' to present these stimuli one by one. However, they have been amended to this list in an order according to the loop I used. I ideally need them to be randomised in order for when they are presented. I have tried:
import random
trials = random.shuffle(trials)
but all I get is TypeError: 'NoneType' object is not iterable... I think it has something to do with the fact that the type of stimulus in the list is stored as the wrong variable type. for the same reason when I try to find the trial number of each presentation (for c in trials: ... trialnum = len(c)) so I can store the trial number along with the response, I get a message about it not being iterable in this form. Basically I feel that these two issues are related in some fundamental way.
Any help would be appreciated
Thanks!
It's because random.shuffle shuffles in place and returns None (that's why you get an error about NoneType), so do
random.shuffle(pairs)
instead of
pairs = random.shuffle(pairs)
As a general comment, you would not generate a lot of TextStims but rather generate one and then update that when you run the experiment. It looks like you're doing a Stroop experiment or something like it. So do something like this:
# General setup
import random
from psychopy import visual, event
win = visual.Window()
# A TextStim and five of each word-color pairs
stim = visual.TextStim(win)
pairs = 5 * [('blue', 'blue'), ('red', 'blue'), ('green', 'yellow'), ('red','red')]
random.shuffle(pairs)
# Loop through these pairs
for pair in pairs:
# Set text and color
stim.text = pair[0]
stim.color = pair[1]
# Show it and wait for answer
stim.draw()
win.flip()
event.waitKeys()