Glossary
Autokinetic Effect
The perceived motion of a stationary point of light in a dark room, caused by involuntary eye movements.
Example:
Staring at a single star in a completely dark night sky for a long time might make it seem like the star is subtly drifting, illustrating the autokinetic effect.
Binocular Cues
Depth cues that depend on the use of both eyes, providing information about distance.
Example:
When threading a needle, you naturally use both eyes to benefit from binocular cues like retinal disparity, which helps you precisely judge the tiny distance.
Bottom-up Processing
Analysis that begins with the sensory receptors and works up to the brain's integration of sensory information.
Example:
When you first encounter an unfamiliar scent, your nose detects the raw chemical signals, and your brain then processes this bottom-up processing to identify the smell.
Brightness Constancy
The perception that an object has a consistent lightness even when the amount of light reflecting off it changes.
Example:
A white shirt appears white both in bright sunlight and in dim indoor lighting, thanks to brightness constancy.
Change Blindness
Failing to notice significant changes in our environment, often due to a lack of focused attention on the specific details that change.
Example:
During a conversation, if the person you're talking to is swapped with someone else during a brief distraction, you might exhibit change blindness and not notice the switch.
Cocktail Party Effect
A specific instance of selective attention where one can focus on a single auditory stimulus, like a conversation, in a noisy environment.
Example:
At a loud party, you can still hear your name being called from across the room, demonstrating the cocktail party effect.
Context Effect
A top-down processing phenomenon where the surrounding environment or a later stimulus influences how we perceive an earlier one.
Example:
Hearing 'eel' in the sentence 'The orange was on the eel' might make you perceive 'peel,' illustrating the context effect.
Cultural Differences
Variations in perception that arise from different cultural backgrounds, beliefs, and experiences.
Example:
Research shows that people from cultures with less exposure to right angles and straight lines may perceive the Muller-Lyer illusion differently, highlighting cultural differences in perception.
Depth Perception
The ability to see objects in three dimensions and to judge distance.
Example:
When playing catch, your depth perception allows you to accurately gauge how far away the ball is and where to position your hands.
Inattentional Blindness
Failing to notice visible objects or events when our attention is directed elsewhere.
Example:
If you're intensely focused on counting the number of passes in a basketball game, you might experience inattentional blindness and completely miss a person in a gorilla suit walking through the scene.
Influence of Expectations
How our preconceived notions and beliefs can shape the way we interpret sensory information.
Example:
If you expect a new movie to be terrible, you might find yourself noticing every flaw, demonstrating the influence of expectations on your viewing experience.
Monocular Cues
Depth cues available to either eye alone, used to judge distance and perceive depth.
Example:
Artists use monocular cues like linear perspective and relative size to create the illusion of depth on a flat canvas.
Perception
The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.
Example:
After touching a hot stove, your brain perceives the heat as dangerous and tells you to pull your hand away.
Perceptual Constancy
The tendency to perceive objects as unchanging (having consistent shape, size, brightness, and color) even as illumination and retinal images change.
Example:
Even as a friend walks away from you, their image on your retina shrinks, but your brain maintains perceptual constancy, so you still perceive them as being the same height.
Perceptual Set
A mental predisposition to perceive one thing and not another, acting as a filter for our experiences.
Example:
Seeing a blurry image, if you have a perceptual set to see animals, you might interpret it as a dog, even if it could also be a cat.
Phi Phenomenon
An illusion of movement created when two or more adjacent lights blink on and off in quick succession.
Example:
The flashing lights on a theater marquee that appear to move around the sign are an example of the phi phenomenon.
Principle of Closure
A Gestalt principle stating that we tend to fill in gaps to perceive a complete, whole object or pattern.
Example:
When you see a dotted outline of a circle, your brain automatically connects the dots to perceive a full circle, demonstrating the principle of closure.
Principle of Continuity
A Gestalt principle stating that we perceive smooth, continuous patterns rather than discontinuous ones.
Example:
If two lines cross, we tend to see them as two continuous lines intersecting, rather than four separate line segments, illustrating the principle of continuity.
Principle of Good Figure (Prägnanz)
A Gestalt principle stating that we tend to organize perceptions into the simplest and most stable forms possible.
Example:
When looking at overlapping geometric shapes, your brain will try to interpret them as distinct, simple shapes rather than a complex, irregular figure, following the principle of good figure.
Principle of Proximity
A Gestalt principle stating that we tend to group together objects that are close to one another.
Example:
When you see three pairs of dots, you perceive them as three distinct pairs rather than six individual dots, thanks to the principle of proximity.
Principle of Similarity
A Gestalt principle stating that we tend to group together objects that are similar in appearance.
Example:
In a crowd, you might group all people wearing red shirts together, even if they are scattered, due to the principle of similarity.
Principle of Symmetry
A Gestalt principle stating that we tend to perceive objects as symmetrical if they are formed around a center.
Example:
When looking at a butterfly, you naturally perceive its two wings as a unified, balanced whole due to the principle of symmetry.
Retinal Disparity
A binocular cue for perceiving depth, referring to the slight difference between the images seen by each eye.
Example:
Hold your finger close to your face and alternate closing each eye; the apparent shift in your finger's position is due to retinal disparity.
Schemas
Mental frameworks or concepts that organize and interpret information from our experiences, helping us make sense of the world.
Example:
Your schema for 'restaurant' includes expectations about menus, tables, and servers, which helps you navigate a new dining experience.
Selective Attention
The ability to focus conscious awareness on a particular stimulus while filtering out other competing stimuli.
Example:
When studying in a noisy coffee shop, your ability to concentrate on your textbook while ignoring conversations around you is an example of selective attention.
Sensation
The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.
Example:
When you touch a hot stove, the feeling of heat on your fingertips is a sensation.
Shape Constancy
The perception that an object's shape remains the same even when viewed from different angles, causing the retinal image to change.
Example:
Even when you view a door from an angle, making its retinal image a trapezoid, you still perceive it as a rectangular door because of shape constancy.
Size Constancy
The perception that an object remains the same size even though the image it casts on the retina changes as its distance varies.
Example:
As a plane flies overhead and gets further away, you still perceive it as a large aircraft, not a shrinking toy, due to size constancy.
Stroboscopic Effect
The illusion of movement created by showing a rapid series of still images, as seen in flipbooks or animated films.
Example:
Watching a cartoon, the smooth motion of the characters is an illusion created by the stroboscopic effect from many individual drawings shown quickly.
Top-down Processing
Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.
Example:
Reading a sentence with missing letters but still understanding it because your brain uses context and prior knowledge is an example of top-down processing.
Unconscious Processing
Mental processes that occur without our conscious awareness, often involving the coordinated work of neural systems.
Example:
While driving, your brain engages in unconscious processing to interpret road signs and traffic patterns without you actively thinking about each detail.