from .mullerlyer_image import _mullerlyer_image
from .mullerlyer_parameters import _mullerlyer_parameters
from .mullerlyer_psychopy import _mullerlyer_psychopy
[docs]class MullerLyer:
"""
A class to generate the Müller-Lyer illusion.
The Müller-Lyer illusion is an optical illusion causing the participant to
perceive two segments as being of different length depending on the shape of
the arrows. Specifically, the line with outward-protruding fins appears longer than
the line with inward-protruding fins.
Each instance of `MullerLyer` contains attributes corresponding to the parameters of the illusion.
Parameters
----------
illusion_strength : float
The strength of the arrow shapes (or fins) in biasing the perception of lines of unequal lengths.
Specifically, the angle of the fins in degrees, i.e., `illusion_strength=20` represents
a 20 degree tilt (away from vertical) of the fins.
A negative sign means that the illusion will enhance the perception of the actual `difference` in lengths
whereas a positive sign reduces this perception.
difference : float
The objective length difference of the horizontal lines.
Specifically, the real difference of upper horizontal line relative to the lower horizontal line. E.g.,
if `difference=1`, the upper line will be 100% longer, i.e., 2 times longer than the lower line.
A negative sign would make the lower line longer than the upper line.
size_min : float
Length of lower horizontal line.
distance : float
Distance between the upper and lower horizontal lines.
"""
def __init__(
self, illusion_strength=0, difference=0, size_min=0.5, distance=1
):
"""
Compute parameters for the Müller-Lyer illusion.
Parameters
----------
illusion_strength : float
The strength of the arrow shapes (or fins) in biasing the perception of lines of unequal lengths.
Specifically, the angle of the fins in degrees, i.e., `illusion_strength=20` represents
a 20 degree tilt (away from vertical) of the fins.
A negative sign means that the illusion will enhance the perception of the actual `difference` in lengths
whereas a positive sign reduces this perception.
difference : float
The objective length difference of the horizontal lines.
Specifically, the real difference of upper horizontal line relative to the lower horizontal line. E.g.,
if `difference=1`, the upper line will be 100% longer, i.e., 2 times longer than the lower line.
A negative sign would make the lower line longer than the upper line.
size_min : float
Length of lower horizontal line.
distance : float
Distance between the upper and lower horizontal lines.
"""
self.parameters = _mullerlyer_parameters(
illusion_strength=illusion_strength,
difference=difference,
size_min=size_min,
distance=distance,
)
[docs] def get_parameters(self):
"""
Returns a dictionary of parameters passed into the Müller-Lyer illusion.
Returns
-------
dict
Dictionary of parameters of the Müller-Lyer illusion, including:
- **Difference** : Objective difference in the target features, by modifying `difference` of mullerlyer_parameters()
- **Illusion** : Name of the illusion, MullerLyer.
- **Illusion_Strength** : The strength of the surrounding context in biasing illusion, by modifying `illusion_strength` of mullerlyer_parameters().
- **Illusion_Type** : `Congruent` if the illusion enhances the perception of the objective difference in the illusion, and `Incongruent` if it reduces the perceived difference
- **Distance** : Distance between the upper and lower horizontal lines, by modifying `distance` of mullerlyer_parameters()`.
- **Bottom_x1** : x-coordinate of the starting point (left) of the lower horizontal line.
- **Bottom_y1** : y-coordinate of the starting point (left) of the lower horizontal line.
- **Bottom_x2** : x-coordinate of the end point (right) of the lower horizontal line.
- **Bottom_y2** : y-coordinate of the end point (right) of the lower horizontal line.
- **Top_x1** : x-coordinate of the starting point (left) of the upper horizontal line.
- **Top_y1** : y-coordinate of the starting point (left) of the upper horizontal line.
- **Top_x2** : x-coordinate of the end point (right) of the upper horizontal line.
- **Top_y2** : y-coordinate of the end point (right) of the upper horizontal line.
- **Size_Bottom** : Length of the lower horizontal line.
- **Size_Top** : Length of the upper horizontal line.
- **Size_Larger** : Length of the longer horizontal line.
- **Size_Smaller** : Length of the shorter horizontal line, equates to `size_min` of mullerlyer_parameters().
- **Distractor_Length** : Length of the distractor fins. Equivalent to half the length of `size_min` passed into mullerlyer_parameters().
- **Distractor_TopLeft_*** : x- and y- coordinates of the top left fins.
- **Distractor_TopRight_*** : x- and y- coordinates of the top right fins.
- **Distractor_BottomLeft_*** : x- and y- coordinates of the bottom left fins.
- **Distractor_BottomRight_*** : x- and y- coordinates of the bottom right fins.
"""
return self.parameters
[docs] def to_dict(self):
"""
Alias for `get_parameters()`.
"""
return self.get_parameters()
[docs] def to_image(self, width=800, height=600, outline=20, background="white", **kwargs):
"""
Create a PIL image of the Müller-Lyer illusion.
Parameters
----------
parameters : dict
Parameters of the Müller-Lyer illusion generated by `mullerlyer_parameters()`.
width : int
Width of the returned image.
height : int
Height of the returned image.
outline : float
The width of the lines in the illusion, passed into `image_line()`.
background : str
Color of the background.
**kwargs
Additional arguments passed into `mullerlyer_parameters()`.
Returns
-------
Image
Image of the Müller-Lyer illusion, defaults to 800 x 600 pixels.
Can be resized
(`resize()`, See https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.resize)
and saved in different file formats
(`save()` See https://pillow.readthedocs.io/en/stable/handbook/image-file-formats.html).
Examples
---------
>>> import pyllusion
>>>
>>> mullerlyer = pyllusion.MullerLyer(difference=0.5, illusion_strength=20)
>>> mullerlyer.to_image()
"""
img = _mullerlyer_image(
parameters=self.parameters,
width=width,
height=height,
outline=outline,
background=background,
**kwargs
)
return img
[docs] def to_psychopy(self, window, **kwargs):
"""Create a PsychoPy stimulus of the Müller-Lyer illusion.
Parameters
----------
window : object
The window object initiated by `psychopy.visual.Window` in which the stimulus will be rendered.
**kwargs
Additional arguments passed into `mullerlyer_parameters()`.
Returns
-------
In-place modification of the PsychoPy window (No explicit return).
Examples
---------
>>> import pyllusion
>>> from psychopy import visual, event
>>> # Create parameters
>>> mullerlyer = pyllusion.MullerLyer(difference=0.5, illusion_strength=20)
>>> # Initiate Window
>>> window = visual.Window(size=[800, 600], winType=`pygame`, color=`white`)
>>> # Display illusion
>>> mullerlyer.to_psychopy(window)
>>> # Refresh and close window
>>> window.flip()
>>> event.waitKeys() # Press any key to close
>>> window.close()
"""
_mullerlyer_psychopy(window, self.parameters, **kwargs)
