I need advice about one stimuli

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1

Hello all,

I am currently working on an experiment. In short, I need the arrow stimulus. I don’t want to use pictures. What suggestions do you have about it?

I read that someone did the arrow stimulus as in the link below, but since I’m a beginner in python coding, could you please tell me how I can do this in a more simplified way?

Thank you in advance,

2

They might not be the prettiest you could do this “<-- / -->”

3

Go to the demos menu, and from the “Coder” demos, select shapes.py and run it. It is a demo of creating arbitrary polygons. This is code from it that creates an arrow-shaped stimulus:

arrowVert = [(-0.4,0.05),(-0.4,-0.05),(-.2,-0.05),(-.2,-0.1),(0,0),(-.2,0.1),(-.2,0.05)]
arrow = ShapeStim(win, vertices=arrowVert, fillColor='darkred', size=.5, lineColor='red')

If you’re not up for coding this yourself, you could probably just use the Polygon component in Builder. On its “basic” tab, select “Custom polygon” for the shape, and paste in the list of vertices given above, i.e:

[(-0.4, 0.05), (-0.4, -0.05), (-.2, -0.05), (-.2, -0.1), (0, 0), (-.2, 0.1), (-.2, 0.05)]
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5

We need more detail to suggest how to help – “it doesn’t work” doesn’t tell us anything useful.

6

I also think image or polygon components are best for maximizing your control over how the arrow stimulus appears, so if images are not an option, I would opt for the polygon component.

However, if you wanted to use text components you could try the unicode character arrows:
U+2190 = ←
U+2191 = ↑
U+2192 = →
U+2193 = ↓

The text box of your text component will contain: ← or whichever arrow you want to display.

If you are setting the arrow in a different direction every repeat, the text component would be:
$VAR
and column VAR in your trial spreadsheet would contain the unicode symbol: ←

I tested this in PsychoPy 2022.1.1 Builder and it seemed to work in both PsychoPy and PsychoJS.

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7

I’m also searching for a method for creating an arrow using Polygon component. The vertices work perfect when I use PsychoPy locally (Thank you :smiley:), but when I converted to PsychJS and uploaded online, the arrow became a rectangle. It is a puzzle, I didn’t change the values, the shape changed :sweat_smile:.

8

It looks the option for custom polygon components doesn’t work fully in PsychoJS yet. bsclod’s solution in that thread might work for you.

  • create your Polygon component as normal
  • add a code component with the following in begin routine (code written in python, the auto-translate option will convert it to JS):
NAME_OF_COMPONENT.vertices = [LIST OF VERTICES]

For example, if you named your Polygon component arrow, and want to use the vertices above, your code might be:

arrow.vertices = [(-0.4,0.05),(-0.4,-0.05),(-.2,-0.05),(-.2,-0.1),(0,0),(-.2,0.1),(-.2,0.05)]

I tested this in PsychoPy 2022.2.4 builder and it works in both PsychoPy and PsychoJS.

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