Lecture 4 Flashcards
What is the difference between sensation and perception?
-Sensation :
§ The process of our sense organs receiving information about the world
§ This information is raw, fragmented, and asemantic
-Perception :
§ Our experience of sensed information, which is compile by the brain
§ This experience is relatively unified and meaningful
Do humans ever consciously experience pure sensation?
Humans never experience pure sensation
What are the four main Gestalt principles?
§ Principle of proximity
§ Principle of similarity
§ Principle of good continuation
§ Principle of closure
Define feature analysis and template model.
Feature analysis = detecting features and their combinations
§ Stimuli are thought of as combinations of elemental features
§ We can perceive an object because what we store in our long-term memory are its parts/features
§ We compare retinal image and see what object in long-term memory has the most features that match the object.
Template model = comparing whole images to past experiences
§ Features are simpler
§ Computationally less intensive
§ Flexible in terms of real variation
§ E.g., Instead of looking at a zebra by its stripes, colors, and shapes (features) separately, looking at a whole zebra and comparing it to past zebras that you’ve seen
What are semantic regularities?
-Semantics = meaning
-Semantic regularities = functions common to a scene
§ What does it mean to go to a restaurant? The function of a restaurant is to provide food
What is experience-dependent plasticity?
-Our experiences shape our brains
-Specialized neurons
§ Respond selectively to horizontals and verticals
§ Kittens – raised in only horizontal or vertical environments changed number of neurons
-Role of culture in perception
§ Culture = social environment
§ Humans are social animals
§ If our environment shapes our brains, then probably the social environment does too
How might culture influence visual perception?
Ebbinghaus illusion
§ Processing styles
* Field-dependence = context-dependence = holistic processing style
* Field-independence = context-independence = analytical processing style
-Many studies show that some South East Asian cultures are more context-dependent than some American/European cultures
§ Being context-in/dependent may relate to social environment § Individualism vs Collectivism
-Caveat: Best to avoid East vs West thinking
§ Is the “West” really the whole western part of the globe? Is the “East” really the whole eastern part?
No.
§ Himba live in North Nambia and share context-dependence
Name the parts of the human eye and their functions
-Cornea - the clear membrane covering the visible part of the eye
§ helps gather and direct incoming light
-Iris - colored part of the eye
§ The muscle that controls the size of the pupil
-Pupil - opening in the middle of the iris
§ Changes size to allow different amounts of light to enter the eye
-Lens - transparent structure located behind the pupil
§ Actively focuses, or bends, light as it enters
the eye
-Retina - thin, light-sensitive membrane located at the back of the eye
§ Contains sensory receptors for vision:
-Rods - Long, thin, blunt receptors, highly sensitive to light, but not to color
§Primarily for peripheral and night vision
-Cones - Short, thick, pointed sensory receptors
of the eye that detect color
§Primarily for color vision and acuity
What is binocular vision?
Two overlapping fields of view create the perception of depth
Describe the 3 depth cues
-Texture gradient
§ Elements tend to appear more closely packed
together as the distance from the view increases
-Stereopsis
§ The ability to perceive 3D because two eyes
receive slightly different view of the world
-Motion parallax
§ Provides 3D information when an object is in
motion
§ As more distant points move they will move more slowly across the retina than closer points.
What is an astigmatism?
When your cornea or lens has a different shape than normal, creating two or more image points on the back of the eye.
What are bottom up and top down processing?
Bottom-Up Processing
§ Eye-to-brain
* Information from the physical stimulus is used to
help recognize a stimulus.
*Start with small bits of information and
combine them to form your perception.
Top-Down Processing
§ Brain-to-perception
* Information from the general context is used to help recognize a stimulus.
* High-level general knowledge contributes to
the interpretation of the low-level perceptual
units.
What are the when and where pathways?
- “where/how” (path to parietal cortex, dorsal stream): specialised for spatial relations )
- “what” (path to temporal cortex, ventral stream): recognition of objects
What brain region is responsible for face recognition?
Fusiform gyrus : The region of the temporal lobe that responds when faces are present in the visual field
What did we learn from the Greebles experiment?
The fusifrom face area in the participants’ brain responded just as well to greebles as it did to human faces -> to test our recognition
