10A - The Fallibility Of Visual Perception Flashcards
Visual Illusions
An illusion created by a misinterpretation (distortion or mistake) of the reality of a visual stimulus
Müller-Lyer Illusion
Müller-Lyer illusion is the misinterpretation of two lines of equal length, each with different shaped ends. One line has arrowheads at each end of the line, while the other line has feathertails at each end
Convergence
Biological depth cue that involves the brain interpreting tension changes in the muscles around the eyes
Fallibility Of Perception
In most cases, our perception of the world is accurate and reliable; however our perception is not infallible
Two ways our perception can be fallible is from the stimulus itself or from how the sensory information is processed in the brain, or both
These include visual illusions & agnosia
Social Explanation (Müller-Lyer)
Carpentered-World Theory-
The theory that the two figures in the Müller-Lyer illusion represent three dimensional objects viewed in our environment, for example, a Western rectangular house
Biological Explanation (Müller-Lyer)
It can be described using the apparent distance theory, which states that if two objects cast the same sized retinal image, but one is perceived to be further away, our brain interprets the more distant object as being larger
Top-Down Processing is used by brain to make sense and determines that the distant feather tail is can only project the same sized retinal image if it is longer originally, therefore incorrectly believe arrowhead line as being shorter
Müller-Lyer Limitations
This is because the illusion persists even if the feathertail and arrowheads are replaced with differently shaped ends and when the lines are turned on their side, which would not create perceived depth as a result of familiarity with Western building design
Theories are limited and flawed
Ames Room
Specially constructed, trapezoid shaped room, designed to create the visual illusion that it is rectangular, for an observer viewing the room through a peephole
Biological And Social Explanation (Ames Room)
An observer can only view the room through a peephole, using only one eye at a time, preventing them from using binocular depth cues
The shape of the illusion of a rectangular room is maintained in the observer’s brain using shape constancy
The illusion is reinforced by top-down processing where the observer has been raised in a culture in which rooms tend to be rectangular – this is what they expect to see
Spinning Dancer Illusion
An illusion in which a dancer can be perceived as spinning clockwise or anticlockwise, and the same viewer can alternate between perceiving a clockwise or anticlockwise spin
Visual Agnosia
Brain disorder that interferes with one’s ability to recognise or identify objects, people or sounds using one or more of the senses, despite the affected sensory system being otherwise fully functioning
Types Of Visual Agnosia
Apperceptive-
An inability to recognise familiar visual stimuli due to problems with processing perceptions
Associative-
An inability to recognise familiar visual stimuli, despite having no problems with processing perceptions
Prosopagnosia-
Type of visual agnosia involving an inability to recognise the faces of familiar people
Retinal Image
The image of an object formed on the retina of the eye
Perceptual Constancy (Bio (Examples))
The mind’s ability to perceive a visual stimulus as remaining constant even though the visual information sent to the brain about the object shows changes in shape, size, brightness and orientation
Shape Constancy
Ability to perceive an object’s actual shape, despite changes in the retinal image of the object
