Hello,
we’re using the staircase procedure to calculate a threshold for a visual yes-no detection task. Participants are supposed to have a 75% threshold of answering correctly. We set up the QuestHandler as described in the documentation, but when trying out the titration, we get around 100% correct instead of the desired 75%. What are we doing wrong?
Thanks in advance!
staircase = QuestHandler(
startVal=0.5,
startValSd=0.2,
pThreshold=0.63, #because it is a one up one down staircase
gamma=0.01,
nTrials=100,
minVal=0,
maxVal=1
)
for contrast in staircase:
key = []
stimulus.opacity = contrast #update the difficulty or contrast from the staircase
while not key:
draw_stim(noise, stimulus, reddot, annulus) # draw the stimulus
window.flip()
key = kb.getKeys(keyList=keys)
if keys[1] in key: # if they didn't see it
print("no")
response = 0
staircase_means.append(staircase.mean())
else:
response = 1
print("yes")
staircase_means.append(staircase.mean())
staircase.addResponse(response)