Intro to perception 1 (Lecture 2)
Describe the difference between conscious perception and recognition
Conscious perception: knowing that something is there (sound, sight, etc.)
Recognition: being able to assign meaning to it
Knowledge is often used for __________
Knowledge is always used for ____________
Conscious perception; recognition
What is light?
Electromagnetic radiation that is part of the electromagnetic spectrum
Both a particle and a wave
Name the two photoreceptors
Rods and cones
Photoreceptors representing lighter regions generate ______ lateral inhibition than photoreceptors representing darker regions
Photoreceptors representing lighter regions generate ___ more___ lateral inhibition
Name 2 medical breakthroughs that have restored perception to people
Artificial retina
Cochlear implants
Prosthetic limbs that can feel
Brain implants for vision
Name the 3 types of perception experiments
Stimulus-behavior
Stimulus-physiology
Physiology-behavior
Compared to humans, what can bees see?
Bees see less visible light than humans (can't see red), but more UV
For seeing in the dark, when do we rely on cones, and when do we rely on rods?
Daily double: what part of our visual field has better dark vision early on vs later on?
After the light dims:
Cones: 0-10 mins
Rods: 10-30+ mins
The center of our visual field is better at dark vision earlier, whereas the periphery is better later
__________ allow photoreceptors to send signals to each other.
__________ allow ganglion cells to send signals to each other.
___Horizontal cells__ allow photoreceptors to send signals to each other.
__Amacrine cells___ allow ganglion cells to send signals to each other.
What are 3 senses that other animals have that we don't?
Magnetoreception
Electroreception
Infrared vision
List 3 bottom-up influences on the perceptual process
Salient information
Motion
Changes and abrupt onsets
Powerful stimuli
What are 3 reasons light is particularly useful for vision?
Light passes through the atmosphere
Light reflects off most things
Light waves are a good size to allow us to see detail (not huge and not super tiny)
Name three properties of visual pigments (e.g., where they are, what they do)
- They are located on the rods and cones
- They change shape in response to light
- They do transduction
- They regenerate
- They absorb light, but only the specific wavelengths we can see
- They are more sensitive to the dark when more of them have regenerated
Describe 3 properties of infant vision and/or photoreceptors.
Infant cones are shorter and have less surface area for visual pigments
Infants' central vision is poor, but their peripheral vision is adult-like
Describe receptor processes, using at least 2 key terms that you learned in the class, and give an example for a specific sense
Receptors convert the proximal stimulus into electrical signals via transduction
Visual receptors turn light into electrical energy
List 4 examples of top-down influences on the perceptual process
Knowledge
Memory
Goals
Expectations
Reward and motivation
Name 2 eye conditions and their corresponding part of the eye
Glaucoma - aqueous humor
Astigmatism - Cornea
Cataracts - Lens
Myopia (nearsightedness) / hyperopia (farsightedness): lens
(Acanthamoeba - cornea)
Later lectures:
Diabetic retinopathy (floaters caused by retina damage)
Macular degeneration - center of the retina (aka macula, which includes the fovea)
Retinal detachment - caused by injury to the retina
Define the fovea, and name the three reasons why it is special
The fovea: the center of our retina, and the center of our visual field as a result
1. Has only cones, and cones are higher resolution
2. The light is focused there (by the cornea and lens)
3. The neural cells are pushed aside, forming a pit, so light gets to photoreceptors directly
How do neural convergence and spatial summation differ between the fovea and the rest of the retina?
What is the consequence of this for light sensitivity and resolution?
Neural convergence is lower in the fovea, meaning spatial summation is lower in the fovea
Fovea is less light sensitive but higher resolution
Name the steps of the perceptual process, in the correct order
Distal stimulus, proximal stimulus, receptor processes, neural processing, perception, recognition, action
In lecture, I showed you an experiment that had a blob with various backgrounds (e.g., on a road vs on someone’s foot). What did that experiment illustrate?
Contextual knowledge is used to recognize objects
Through the process of ________,
the ______ muscles around the lens cause the lens to ______ in response to closer stimuli.
Daily double:
________: difficulty seeing close objects
________: difficulty seeing distant objects
Through the process of _accommodation_,
the _ciliary_ muscles around the lens cause the lens to _thicken_ in response to closer stimuli.
Daily double:
_Hyperopia_: difficulty seeing close objects
_Myopia_: difficulty seeing distant objects
Name the order in which light travels through the layers of the retina, AND the order in which the neural signal travels through the layers of the retina
Light: passes through ganglion cells, then bipolar cells, then photoreceptors (and visual pigments on them)
Neural signal: generated by photoreceptors (using visual pigments), then passed to bipolar cells, then passed to ganglion cells
If a light is shined on a visual receptor, what happens to nearby receptors?
What is this phenomenon called?
What does it do for vision?
If a light is shined on a visual receptor, nearby receptors decrease firing.
This is called lateral inhibition
It enhances vision for edges and increases contrast