Perception Flashcards
Sensation vs. Perception
Sensation: Seeing blue lines (basic sensory experience)
Perception: Your brain’s interpretation-like how many appendages did you see (2 or 3). Perception is subjective and sometimes your brain “chooses” based on how it organizes information
What is the Stroboscopic effect?
Wheels on a car sometimes look like they’re moving backward when they are moving forward. This is because your brain processes visual information in chunks and makes predictions when information is missing. Guesses how wheel moves but guess could be wrong.
What does the Primary Visual Cortex (feature detectors in central lobe) do?
Detects features such as orientation, color, dimensions, moving or not.
What is Feature Integration Theory?
It explains how we perceive objects by first breaking them down into basic features and then putting those features together to form a complete picture. We process things parallel and then integrate serially.
Serial Processing Vs. Parallel Processing
Parallel: Basic details that are noticed at once, “it’s green” “it’s moving”.
Serial: After detecting basic features your brain puts together what is going on especially is the object has a lot of similar looking features.
What is illusionary conjunction?
Occurs when your brain mixes up features from different objects. This happens because during feature integration your brain might detect features correctly but fail to combine them accurately.
What is Gestalt Psychology/ principles?
“Sum is greater than parts”
Proximity
Similarity
Connectedness
Common Fate
Good Continuation
Closure
Good form
Gestalt Principle: Proximity
Objects close together are perceived as a group
Similarity
Objects that are similar in color or shape are seen as a group.
Good Continuation
We prefer smooth, continuous lines or patterns
Connectedness
Connected together=perceived as one whole object
Common Fate
Things that move in the same direction or speed are seen as the same object
Closure
Your brain fills in gaps to perceive complete shapes.
Good Form
We group things that appear uniform or even.
What is depth perception?
The ability to perceive the world in 3D and to judge the distance of objects. Allows us to know how far away objects are from us and from each other.
What are Binocular Cues/disparity?
Cues that require both our eyes working together, our eyes are spaced apart so each eye gets a slightly different view of the world.
Binocular disparity: The slight difference between the images seen by your left and right eyes. (close left eye then switch to other eye, what you’re looking at seems to switch position.
Monocular Cues/Motion Parallax
Motion parallax: depth cue based on motion where objects closer to you seem to move faster across your field of vision than objects that are farther away.
Pictorial Cues
Cues used in paintings or photos to create the illusion of depth.
Depth Cues in size perception
Size consistency: we perceive objects as having a constant size even when their distance from us changes.
Depth illusions:
When depth rules in your brain are tricked you get illusions
Ames Room
A trapezoid room that looks normal from the front but is actually distorted. People standing in different parts of the room appear to be different sizes because the brain assumes the room is a normal shape.
illusory contours
sometimes we perceive edges and shapes that aren’t actually there because our brain fills in the gaps
illusory lightness differences
the brain interprets light and shadows in ways that can trick us into seeing areas as lighter or darker than they actually are i.e checker shadow illusion
Hollow Face illusion
When looking at a hollow mask, your brain will perceive it as a normal face that pushed outwards even if the face is pushed inwards.
Penrose Triangle
An illusion where a 2D triangle seems to be a 3D object but its not.
Recognizing Objects: Template Matching
Your brain recognizes objects by comparing them to stored mental templates, if the input fits a template closely enough your brain identifies the object.
Problems occur when a rotated version does not match a template.
Recognizing Objects: Feature Nets
Proposes that we break down complex visual information into simpler components or features.
Feature Nets: Detectors
Detectors respond to specific features or stimuli (angles, lines, curves).
Feature Nets: Layers
Lower layer detects simple features, while higher layers combine these features to recognize more complex shapes and objects.
Feature Nets: Activation
Detectors that correspond to features become activated
Feature Nets: Response Threshold
Each detector has a threshold level of activation that must be reached for it to “fire” and contribute to the recognition of an object.
Feature Nets: Priming
Previous exposure to certain features can increase the activation of specific detectors.
Recognition by components: GEONS
Basic shapes (like cones, cylinders) that help recognize objects. Even when parts of an object are missing, you can often recognize it by filling in the missing GEONS.
Evidence for GEONS?
Removing contours that make up the boundary of the GEONS affects what you see=no longer can see the shape.
What is agnosia?
Can’t recognize objects, can’t put geons together.
What are some problems for GEON theory?
GEONS work well for recognizing general categories (lamps, dogs) but not for specific individuals. Example: Recognizing different dogs that are made up of similar neons is harder because they look alike.
Brain Areas Involved in Object Recognition:
Occipital to Temporal
Helps recognize what an object is
Brain Areas Involved in Object Recognition:
Occipital to parietal:
Helps recognize where an object is and how it is moving.
Ventral Lesion (lower pathway)
Unable to do object “what” task, but good at “where” task.
Dorsal Lesion (upper pathway)
fine at object recognition, could not do “where”
Face Processing:
Fusiform Face Area(FFA)
A specialized brain area for recognizing faces
Prosopagnosia
Damage to FFA leads to face recognition problems
Perception and Motion:
Binocular Rivalry
Brain activity can shift between different visual perceptions
Top-Down influence
Context matters in recognition. We recognize objects faster when they’re in familiar context.
Prosopagnosia
Able to identify people through cues like hair or style, never developed face recognition.
Tracking Multiple objects (Object file theory)
Your brain tracks objects as they move through space and updates their positions over time.
AMODAL (without censoring information)
surfaces complete behind occluding surface
MODAL completion
You don’t see an overlap, it’s not one shape but there are no boundaries, you don’t assume a rectangle is on top of it.
Object Files: Experiment
Object-Review Paradigm
Task?
Did the target letter appear anywhere in the preview display? (They will move but just ask if they were present). Response time between congruent and incongruent trials will be compared.
Object Files: Experiment
Object-Review Paradigm
Results:
Novel: (letter did not appear in preview) Showed high response time.
Congruent: (Where you expect it to be) Showed high response time.
Incongruent: (where you don’t expect it to be) showed higher response time.
