Module 18-20
Module 18- Basic Concepts of Sensations and Perceptions
Module 19- Vision Sensory and Perceptual Processing
Module 20- The non Visual Senses
Perception
The process which your brain organizes and interprets sensory input
Sensation
The process which our sensory receptors and nervous system get stimulation from the outside
Bottom Up Processing
Starts at sensory receptors and goes to a higher level
Top Down Processing
Creates perceptions from sensory input by drawing from our experience and expectations
Transduction
All of our senses
Receive sensory information often using specialized receptor cells
Transform that into neural impulses
Deliver neural info to our brain
defintion
The process of changing one from of energy to another form
Psychophysics
Studies the relationship between physical energy we can detect and the effect on our psychological experience
Threshold
Absolute Threshold
Difference Threshold
The minimal stimulus needed to detect a certain stimulus 50% of the time
Signal detection theory
Predicts when we will detect weak signals
Subliminal Primal
Remembering a memory because of a stimulus.
Happens unconsciously often
The minimum difference needed to see a difference between two stimuluses
Weber's Law
Ernest Weber's principle that to be perceived different, they must differ by a constant minimum percentage
Light Energy
Our eyes get and change light energy to neural messages to be sent to the brain
The Stimulus Input: Light Energy
When we look at something red we aren't actually looking at particles of red, but red wave lengths rejected by the red thing
Wave length
The distance from the peak of one light to or sound wave to the peak of the next
Hue
The color which is seen on the wave length
Intensity
The amount of energy in a light wave or sound wave
Measured in brightness or loudness
Calculated by waves hight
The Eye
Cornea
Bends the light to help provide focus
Pupil
Small hole in the eye to let light come through
Iris
Colored tissue around the pupil to adjust the size of it
Lens
A clear layer behind the pupil that changes shape to help focus images on the retina
Retina
A light sensitive inner surface that has rides and cone receptors and layers of neurons to begin process of visual information
Rods
Retinal receptors that detect black, white and gray, needed for peripheral and twilight visions when cones don't respond
Cones
Show fine detail and color
Retinal receptor cells that are near the center of the retina and function in day time.
Accommodation
The process which lens changes shape to focus on near/far objects
Peripheral Vision
What can you see from side to side when you're looking straight ahead
Twilight Vision
What you can see when it's dark
Optic Nerve
Nerve that carries information / neural impulses to the brain
Blind Spot
The point where the optic nerve leaves the eye
Creates a blind spot because there are not receptor cells there
Johannes Kepler
Showed that retina does get upside down views but didn't understand how it got flipped up
Da Vinci said it was bc of the liquid in the water
Today's answer
It get's flipped back by the brain
Information Processing in the Eye+ Brain
Retinal Processing
In Steps
- Light goes through the retina's out layer of cells
- Reach the back of the eye where rods and cones are
- Activates bipolar cells
Light energy will trigger chemical reaction
- Bipolar cells activate Galigon cells (Axons strands form Octive nerve together
- Impulses go from Octive nerve to thalamus where it is ready to send info to different parts of the brain
Fovea
The central focal point in the retina where the cones cluster around
Each cone has a direct "hotline' to brain
These connections help keep detail and and color better
Share bipolar cells with each other which send combined messages
Enable black and white vision in dim vision
Color Processing
When we something red, it is actually the red wave length bouncing off the thing
Young Helmhotz's trichromatic (three color) theory
Retina gas 3 color receptors. Most sensitive to red, green and blue when stimulated
Can make any color combination
People who are color blind just don't have functioning red/green/blue receptors
Why can color blind people color blind people see yellow and not purple?
Edward Hering Found answer in after images formed that there must be other color processes
red vs. green perception and blue vs yellow perception
Opponent process theory
The theory that opposing retinal processes enable color vision
Feature Detection
Scientists used to think that the brain was like a movie screen that eyes project images on
David Hubel and Torsten Wiesel 1979
Showed our brain breaks down images and restores them
Feature detector
Different images trigger different parts of the brain
Parallel Processing
The process of many different aspects such as motion, depth, form and color working together at the same time.
Brain's natural mode of info processing for many functions
Simplified Summary of Visual Information Processing
Scene
Retinal Processing
Feature Detection
Receptor Rods and cones
bipolar cells
ganglion cells
Brain detector cells respond to specific features- edges lines+ angles
Parallel Processing
Recognition
Brain Cell teams process combined information about movement, form, depth and color
Brain interprets the constructed imaged based on information from stored images
Perceptual Organization
We organize sights into meaningful perception
Gestalt
Pieces of information organized as a whole by our brain
Form Perception
Form and Ground
The organization of the visual field into objects (the figures) that stand out from the surroundings (the ground)
Grouping
The tendency to organize stimuli into coherent groups
3 examples
Proximity
We group nearby figures together
Continuity
We see smooth continuous patterns than random patterns
Closure
We fill gaps to create a whole object
Depth Perception
The ability to see objects in 3D although the images that strike the retina are 2D
Visual Cliff
Allows us to judge distance
Elenor and Richard Walk (1960)
A laboratory device for testing depth perception in babies and young animals
Binocular Cues
Depth Cues such as retinal disparity, depends on use of both eyes
Retinal Disparity
By comparing images in both retinas the brain figures out the distance. Greater disparity= closer the image
Monoclear Cues
Depth cues such as interposition and linear perspective to either eye alone
Interposition
An object that blocks the view of another it's closer
Linear perspective
The sharper the angles from stuff the farther away it is
Motion Perception
Shrinking objects are going away
Growing objects are coming closer
Stroboscopic movement
Rapid images seen as one continues movement
Phi phenomenon
An illusion of movements when 2 or more adjacent lights blink on and off in quick sensation
Perceptual Constancy
Perceiving objects as unchanging even when environment changes
Color and brightness Constancies
Experience of a color depends on context
Color Consistency
Being able to see the same color wavelengths even when the environment around it changes
Brightness Constancies
We have constant brightness even when surrounding light changes
Relative luminance
What constancy depends on the light an object reflects around it's surrounding
She and Size Consistencies
Shape consistencies
We perceive familiar objects as a constant shade even though our retinas get changing images of them
Ex: Door, it looks like a trapezoid when it's more and more open but we still see it as a rectangle
Size Consistencies
We perceive objects having the same size even though our distance from them is different
Ex: A car farther away is smaller but it is still the same size
Perceptual Interpretation
Experience and Visual Perception
William Molynuex
"Is man born blind and is taught to see and is taught by sense of touch
Answer is no
Tested formal blind people and people with cataracts
Could tell the difference between ground and stuff on it.
Can sense colors
Can't recognize objects by touch but not as much as Molynuex thought
Baby Animals wore an eye patch and tested it's vision
It was different, they knew colors but not shapes
Critical Period
An optimal period in babies to have exposure to sensors
The younger the children are, the better
Perceptual Adaptation
To be able to adjust to an artificially displaced or inverted visual field
Humans are able to adjust
George Stratton
Wore glasses that flipped world upside down, at first it was bad but he adjusted.
When he took them off he adjusted to the world as right side up again
The Other Senses
Touch
As babies through adults, touch is important
Sense of touch is dependent on 4 things
Pressure
Warmth
Cold
Pain
Pain
Understanding Pain
Women are more sensitive to pain
Gate Control Theory
The spinal cord has a "gate" that blocks pain or lets them go to the brain.
Opened by small impulses
Closed by large impulses or info coming to the brain
Nociceptors
Nerves that feel pain
Influences of pain
Biological
Activity in spinal cord and brain
Genetic differences in endorphin production
Brain's interpretation of CNS activity
Psychological
Attention to Pain
Learned based on experience
Expectations
Social Culture Influences
Presence of others
Empathy of others
Cultural Experiences
Hypnosis and Pain Relief
Hypnosis
One person suggests to another about certain perceptions or feelings
Dissociation
A split in consciousness which allows some thoughts and behaviors to occur at the same time as others
Posthypnotic Suggestion
Made during hypnosis to be carried out after the subject isn't in hypnosis anymore
Used to help get rid of unwanted feelings or behaviors
Sensory Information
The principle that one sense may influence another like when the smell of food affects the taste
Embodied Cognition
The influences of bodily sensations, gestures and other states on cognitive performances and judgments