Sensation and Perception - Will Flashcards
Define sensations
features of the environment that the brain uses to create meaning
define perception
an understanding of the world made based off of processed stimuli
What is bottom-up processing?
neural processing that starts with the sensation
What is top-down processing?
combining sensation with with our understanding of the world
What are the 3 musts of sensation?
Detection
transduction - translated into a message the brain can understand
transmission - message sent to the brain
What is psychophysics?
The study of the link between characteristics of the physical world and the understanding of them.
Define absolute threshold
It is the minimum amount of stimulation needed for us to notice something 50 percent of the time.
What are the 6 Gestalt principles and briefly describe them.
- Principle of proximity - objects close to each other will be perceived as groups
- Principle of similarity - objects that are physically similar to each other will be grouped together
- Principle of closure - people tend to perceive whole objects when parts are missing
- Principle of good continuation - When people see two crossing lines, they assume they continue.
- Principle of common fate - objects moving together will be perceived as a group
- Principle of figure ground - people instinctively see things as part of the foreground or background
What wavelengths can people typically see?
400-700nm
What determines the hue of a colour?
Wavelength determines it. Longer wavelengths will be on the red side of the spectrum and shorter wavelengths will move towards the purple side.
What determines the brightness of a colour?
The amplitude of the wave.
What is the retina?
The thin layer on the back of the eye that contains photosensitive receptor cells.
What is the cornea?
The front of the eye, the first thing light passes through. It focuses most of the image.
What is the pupil?
The hole in the eye that light can go through. It expands and contracts based off stimuli.
What is the iris?
It is the ring of tissue around the pupil. It contracts and dilates the pupil.
What process is accommodation? What part of the eye does it use?
Accommodation is the lens (the layers of tissue behind the pupil) changing shapes in order to bring them into focus in the retina.
When using close vision, what is the shape of the lens?
Thicker and rounder.
If I have myopia what is the problem with my lens? What can I see well?
Myopia (nearsightedness) mean my eye lenses are too long so I cannot see objects far away.
If my eye lenses are too short and I cannot see close, what am I diagnosed with?
Hyperopia (farsightedness)
What photoreceptor is sensitive to low light? bright light?
Rods are sensitive to low light. Cones are sensitive to bright light/color
What is the fovea? What cells are typically found most here in humans?
The fovea is the part of the retina directly behind the pupil. In humans cones are mostly found here.
How long does it take for rods to increase sensitivity in the dark?
approx. 20m
Where are diffuse bipolar cells found?
They are found under multiple rods and send the message to a large ganglion cell.
Where are midget bipolar cells found?
They are found under one cone and send the message to a small ganglion cell.
How much of the retina is made of small ganglion cells? What letter are they associated with?
70%, P
What is the optic chiasm? What is its function?
It is where the optic nerves cross and reorganize information.
What is the lateral geniculate nucleus?
The layered part of the thalamus that organizes visual function.
What letter is associated with the large ganglion?
M
Where is the visual (striate) cortex located?
The occipital lobe
what is retinotopic organization?
the organization of the visual pathway that maintains the retinal image
What are feature detectors?
Specialized cells in the Visual Cortex that respond to specific stimuli
What are the two cells of feature detectors? What are they receptive to?
Simple cells are responsive to stationary bars of light at any angle, and complex cells are responsive to vertical bars of light in motion.
What does the ventral stream span?
It goes from the occipital lobe to the temporal lobe to identify the objects
What does the dorsal stream span?
It goes from the temporal lobe to the parietal lobe to understand the location of things.
What are the three types of cones? What do they respond to?
Short, medium, and long. Short cones respond to short wavelengths = blue, medium responds to green and long cones responds to red/orange
What does trichromatic theory entail?
All colors are determined by how many red/green/blue cones are firing and what the mix of them is.
What theory of color is related to complimentary afterimages?
The opponent-process theory
How can we describe the opponent process theory?
The brain is measuring three antagonistic color systems, and seeing what is activated and what is inhibited to what degree.
What are the three antagonistic color systems in opponent process theory?
Red green, blue yellow, and black white
What does the brain use to monitor depth? (2)
The brain uses monocular depth cues and binocular depth cues.
What is another name for monocular cues?
Pictorial cues
What are the 6 monocular cues? Describe them briefly.
- Occlusion -when one thing is in front of another and partially overlaps, the object closer will overlap the farther one.
- Relative height cues interpret position in relation to the horizon. Closer to the horizon is farther away.
3.Relative size -Things closer will seem larger. - Perspective convergence - as parallel lines move away from us, they seem to converge
- Cue of familiar size - When we know somethings actual size we can infer how far it is based on its size.
- Atmospheric perspective - As things are father, they are hazy due to the air pollution in the way.
What are the two ideas of binocular depth cues?
Retinal disparity is the difference between the images of the left and right eye. As things are farther away the images between the two eyes is more similar. The brain also measures how much the eyes need to turn inwards to see how close something is.
What is signal detection in perception studies?
When somebody either says they detect stimulus before they do, or they wait until its confirmed before they say it, we can infer there are individual biases between people’s answers.
What does JND stand for?
Just noticeable difference
What does Weber’s Law state?
The more intense the stimulus, the larger change required to notice a difference.
