Visual illusions

Have a look around you; what can you see? Does everything appear normal to you? What happens when we perceive things to be different from what they are? Differences in perception can be explained in psychology by using visual illusions! Illusions involve misinterpreting visual stimuli in the environment and what our brains think this information is. Our perception appears to vary from reality, and we can struggle to make sense of the things we see.

Visual illusions Visual illusions

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Contents
Table of contents
    • First, we will briefly explore perception and visual illusions in psychology.

    • Then we will look at some types of visual illusions.

    • After, we will see some visual illusions.

    • Next, we will identify explanations for visual illusions examples.

    • Finally, we will briefly examine some perception theories for possible causes of visual illusions.

    Visual Illusions Perception Psychology

    Visual perception is a critical aspect of our survival. It allows us to explore and react to our environment. Visual illusions can confuse our brains into missing visual information or thinking we are seeing something that is not necessarily there, but what exactly do we mean by visual illusions?

    Visual illusions are images or objects that alter our perception to be different from the picture's reality, as the 'illusion' does not make logical sense to our brain.

    Perception can be explored from a psychological perspective using visual illusions by examining what kind of misinterpretations in stimuli affects the majority of people and why. This can help to understand why humans have evolved particular cognitive and visionary abilities and can contribute to creating design features that people find easy and enjoyable to view.

    We can also begin to understand why visual illusions affect us all.

    Types of Visual Illusions

    Visual illusions can vary in how and why they affect our perception. Some can be quite subtle and difficult to distinguish between the real and perceived image. In contrast, others are overwhelmingly tough to look at, where identifying a certain image or pattern is almost impossible.

    A few types of visual illusions include:

    • Cognitive visual illusions - are the most common type of visual illusions. They rely on tricking the subconscious mind based on how you usually infer and relate what you see to what you already know about the world. This causes your brain to think there is a certain image present, even though it is not there or it is something else entirely.
    • Physiological visual illusions - these geometric images contain so many visual cues that the brain sees different depths and lines of travel. They often look different every time, and some can appear to be moving.
    • Literal visual illusions - these are made up of two images that are present at the same time. People can perceive them differently initially and often need the other image in the illusion pointing out to them to distinguish between the first image noticed.

    Visual Illusions Examples

    Several kinds of visual illusions have been created and used by psychologists in perception research over the years. Fantastical images that test the brain's ability to make sense of illogical or ambiguous content have been created to explore perception. Visual illusion examples include:

    • The Ponzo Illusion
    • The Müller-Lyer illusion
    • Rubin's Vase
    • The Ames Room
    • The Kanizsa Triangle
    • The Necker Cube

    The Ponzo Illusion

    Can you guess the visual trick in this illusion from the Italian psychologist Mario Ponzo?

    Visual Illusions, the Ponzo illusion, two horizontal lines appear to be different lengths due to their position on top of two slightly slanted vertical lines, but both horizontal lines are the same length, StudySmarterIn the Ponzo visual illusion, the horizontal lines are the same length. Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)

    Both of the parallel horizontal lines in the Ponzo illusion are the same length! The top horizontal line appears to be longer due to its placement converging at the top of the narrower part of the vertical lines.

    The Müller-Lyer illusion

    Do you notice anything particular about the three lines in the illusion below?

    Visual Illusions, a Müller- Lyer illusion, the three horozontal lines are actually the same length, though at first glance they appear not to be, StudySmarterAn example of the Müller- Lyer illusion, all of the parallel lines are the same length, Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)

    The three long parallel lines are all the same length, as shown in the bottom image, with the lines highlighted in red. Many believe certain lines are longer due to the direction of the arrows at the end - outward arrows are often said to contain longer lines, although this is not the case.

    Rubin's Vase

    Look at the image below. Can you see a vase or two faces?

    Visual Illusions, Rubin's Vase, an image of a yellow vase, in the black edges surrounding the vase two face silhouettes can be seen also, StudySmarterRubin's Vase visual illusion, can you spot a vase or two faces? Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)

    The yellow part of the image shows a vase, but the black parts of the image make up a silhouette of two faces, one on the left and one on the right.

    The Ames Room

    Can you spot the differences between the three circles below? Where do you think the visual illusion here is?

    Visual Illusions, from the viewing area the Ames room illusion makes an uneven room appear to be square, with the person in the top right corner appearing bigger than the person in the top left corner, StudySmarterThe Ames Room visual illusion, Attribution - Alex valavanis, Public domain, via Wikimedia Commons

    The illusion comes from the pink circle (the apparent position of person A) appearing directly opposite and smaller from the viewing point than the green circle (person B). The actual position of person A is further behind the apparent position. Because of the room shape and viewing angle, the distance is perceived to be shorter and, therefore, smaller.

    Person A would look disturbingly small next to person B.

    The Kanizsa Triangle

    Look at the image below. How many triangles can you see?

    Visual Illusions, the Kanizsa Triangle Illusions shows 3, three-quarter circles, a white triangle appears to be in the middle of these circles, even though it is not there in the image, StudySmarterIn the Kanizsa Triangle illusion, how many triangles can you see? Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)

    There aren't any triangles in this image! Your brain fills in the gaps to create a large white triangle in between the gaps of the black circles. People often fill in gaps as well, to say there are three smaller black-lined triangles or one big triangle with a black outline too.

    The Necker Cube

    Which side of the cube below do you notice first?

    Visual Illusions, the necker cube is a 3 Dimensional cube shown in a 2 Dimensional format, StudySmarterThe Necker Cube, which side do you perceive the cube from? Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)

    People can perceive the cube to be angled towards the left and right.

    Visual Illusions and Explanations

    There are several explanations for why we can misinterpret information seen in visual illusions like the ones above. Some of the common explanations include:

    • Ambiguity - the image of a visual illusion can be perceived in several different ways, all of which make sense. Like Rubin's Vase illusion, there is no clear, correct answer, and both images can be seen if looked at for long enough.
    • Depth cues - our visual system uses depth perception to judge how far away or big an object is. Visual illusions cause misinterpretations of visual information by tricking the brain into thinking a part of the image is further away or bigger than it is. For instance, with the Ponzo illusion, the horizontal lines appear to be different sizes because the angle of the two vertical lines makes the top section of converging lines appear further away.
    • Fictions - when we perceive something as part of an image that is not really there, like the white triangle in the Kanizsa triangle illusion.
    • Visual constancy - an object's size, colour and shape can appear to be different due to environmental conditions, but in reality, the object has not altered. For example, in the Ames room illusion, Person A appears smaller, even though they have not shrunk in any way. They are just perceived at an angle that makes it appear that way.
    • Distortions - occur when the aspects of an object appear to be different than what they are. For example, the lines in the Müller-Lyer illusion appear to be of different lengths.

    Depth cues can be monocular (using one eye), which gives a 2-dimensional image or binocular (using both eyes), which creates a 3-dimensional image.

    Possible Causes of Visual Illusions

    There are two main theories of perception that we will briefly explore that can explain some possible causes for why visual illusions work:

    • Gibson's (1966) The Direct Theory of Perception suggests that we perceive the world through our eyes using the information we see directly. Nature influences our perception of the world. Gibson referred to how this direct information about the world is sent to our brain from our eyes as bottom-up processing.
    • Gregory's (1970) The Constructivist Theory of Perception suggests that we use information stored in our brains from previous experiences to perceive the world around us. How we perceive the world is influenced by nurture and external factors from our environment. Gregory referred to this stored information being brought down to our visual senses for interpretation as top-down processing.

    Both of these theories can explain why we fall for visual illusions because the image we see either does not match up with information that we already have stored. So it isn't easy to interpret and understand because we automatically trust what we see in front of us as the truth.

    Either way, our visual system gets easily overwhelmed and misinterprets the image.


    Visual Illusions - Key Takeaways

    • Visual illusions are images or objects that alter our perception to be different from the picture's reality, as the 'illusion' does not make logical sense to our brain.
    • Types of visual illusions include cognitive, physiological and literal illusions.
    • Examples of illusions include the Ponzo, the Müller- Lyer, Rubin's Vase, the Ames room, the Kanizsa triangle and the Necker Cube illusions.
    • Explanations for visual illusions include ambiguity, depth cues, fiction, visual constancy and distortions.
    • The direct and constructivist theories of perception can help explain the possible causes of misinterpreting visual images based on how we might process information. The image can be confusing if the information doesn't match how we interpret the world.
    Frequently Asked Questions about Visual illusions

    What is a visual illusion psychology? 

    Visual illusions are images or objects that alter our perception to be different from the reality of the picture, as the 'illusion' does not make logical sense to our brain.  

    Perception can be explored from a psychological perspective using visual illusions by examining what kind of misinterpretations in stimuli affects the majority of people and why.  

    What are examples of visual illusions?

    Examples of illusions include the Ponzo, the Müller- Lyer, Rubin's Vase, the Ames room,  the Kanizsa triangle and the Necker Cube illusions. 

    What are the 3 types of visual illusions? 

    The three types of visual illusions include cognitive, physiological and literal illusions.

    What are visual illusions caused by? 

    A visual illusion is caused by misinterpreting visual images based on how we might process information in the brain's attempt to make logical sense of reality. The image can be confusing if the information doesn't match how we interpret the world. 

    What do visual illusions tell us about perception?

    Visual illusions can tell us that perception can be different based on how we might process visual information. Our visual systems can get easily overwhelmed and so misinterprets the reality and perception of an image. 

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