How to make the target’s position different from the previous target’s position?

Coding
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1

Hello all,
How to make the position variable different from the previous trail? That is, when the participant does the experiment, the position of trail N and trail N-1 are different. I don’t want to use the method of generating excel tables, I want to realize this randomization in psychopy, where should I add this code?I appreciate your help.

2

Hello,
Here is a possible solution using the random library. This solution will only work for offline experiments but should also be easy to implement for online experiments.

# Start Experiment
import random

def randomLocation():
    return round(random.uniform(-1, 1), 3)

# Start Routine    
currentLocation = [randomLocation(), randomLocation()]

Then, set the position to change on every repeat and set it to $currentLocation.

You might need to reduce the range from -1 → 1, to -0.8 → 0.8, depending on your stimulus size.

Chen

3

Thank you very much!! :partying_face:
But with a little tweaking in the coder,
Put currentLocation = [randomLocation(), randomLocation()] before polygon.setPos()

4

The way I approach this kind of issue, to avoid random locations being too close to previous random locations, is to create a grid of jittered points and then shuffle them.

I’ve just updated my points on a grid demo to include optional jitter. You could create a random list of points with something like

rows = 8
columns = 10
gap = [.1,.1]
jitter = .05
points = []
for Jdx in range (rows):
    for Idx in range(columns):
            points.append([(1+Idx-(columns+1)/2)*gap[0]+random()*jitter-random()*jitter,((rows+1)/2-Jdx-1)*gap[1]+random()*jitter-random()*jitter]) 
shuffle(points)

Then use points[trials.thisN%len(points)] for the location of an object in a loop called trials. %len(points) means that it will go back to the start once all points have been used.

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