EXAM 2 Flashcards
What is the difference between sensation and perception?
Perception: mental processing of sensory information
Sensation: detection of physical stimuli and the transmission of this information to the brain
Be able to differentiate effects on perception that are due to bottom-up vs top-down processes.
Top down processing: perception that is based on previous world knowledge expectations and past experiences.
EX: put together that the horizontal lines look like a B
Bottom up processing: perception that is based on the physical properties of the stimulus
EX: light hits cells in the retina, affecting their firing rate
What does it mean to say that every receptor has an adequate stimulus?
Every sensory receptor has a particular type of stimulus energy to which it is most sensitive
I.e photons for photoreceptors, hair cells mechanically being pushed for hearing
What is the adequate stimulus for photoreceptors (e.g., vs hair cells)?
Photons
Be able to differentiate between a distal stimulus and a proximal stimulus.
Distal stimulus: an object or event out in the world
Proximal stimulus: energies related to the stimulus that we came in contact with
Be able to trace the complete pathway of visual information, from a distal stimulus to V1 (and from 10 class, out to FFA/PPA).
Distal stimulus → back of retina (if up, then lower retinal cells, if down then upper retinal cells—rod/cones, horizontal cell, bipolar cell, amacrine cell, ganglion cell) → optic nerve
Fovea: point of central focus
Photoreceptors (rods and cones) absorb photons of light
Stacks of pigment in the outer segment of rods contain opsin which changes the shape when hit by a photon of light
Left visual field → light side of retina → optic chiasm → Lateral geniculate nucleus → V1 (primary visual cortex)
What is the fovea?
Point of central focus
What are the differences between rods & cones?
Rods:
- Not color sensitive
- Respond to low intensity light (good at night)
- Distributed throughout the retina (NOT IN THE CENTER)
Cones:
- Color sensitive
- Requires higher intensities to respond
- Concentrated near the center of retina (FOVEA)
What do the layers in the lateral geniculate nucleus indicate?
Layers 2,3,5 – info from ipsilateral eye (same side)
Layers 1,4,6 – info from the contralateral eye (opposite side)
Understand the idea of a retinotopic map
- Neural activity in the retina and brain organizes information about locations of objects and parts in visual space.
- Retinotopic map: a map in which each point in brain tissue corresponds to a location in the retina
Be able to explain how visual perception of edges could be enhanced through lateral neural connections (“lateral inhibition”)
- Moch bands
- Enhanced edges is BOTTOM-UP processing (can only enhance what is already there
- When the high intensity and low intensity lights hit, the interconnected cells receive different intensities – that results in lateral inhibition as bipolar cells respond differently at the edges with 2 different shades right next to one another
Recognize / identify examples of visual perceptual grouping principles.
Perceptual grouping: sensory information is grouped into organized wholes
Gestalts: forms/shapes
Gestalt Principles:
a. Proximity: group close items together
b. Similarity: group similar items together
c. Continuity: group edges/contours together that have the same orientation
d. Closure: complete figures that have gaps
e. Illusory contours: perceive contours and cues to depth even when they do not exist
f. Object constancy: maintenance of constancy across various perceptual contexts (lighting, size, shape, ect.)
i. Tea cup in different orientations can still be identified as a stimulus
Transduction: changing the format of the stimulus to a neural signal
Be familiar with the different types of retinal cells and what they are “optimized” for with regard to the range of intensities and wavelengths of light. How does this cell specialization result in color vision? (What is the trichromatic theory of color vision?)
Wavelength: the distance between 2 corresponding points on a wave
Frequency: the number of waves that pass a point in space during any time interval, usually one second
Cones detect color; there are 3 different types of cones, small, medium, and large that corresponds to the wavelengths that they are stimulated by (small wavelengths, medium wavelengths, and large wavelengths)
Small = Blue
Medium = Green
Large = Red
Be able to identify the color that would be perceived given different wavelengths of light. (What color would you perceive if presented with “red”, “green”, and “blue” wavelengths simultaneously?)
All 3 colors simultaneously would be perceived as white where all the cones are perceived as white
Purple does not exist: mix of red and blue light
See different colors depending on the neural response which can be mixed depending on other cone cells stimulated
Be able to explain two different ways of perceiving a color such as yellow, given that there are no cones that respond to “yellow” wavelength.
One way is that you could have it is red and green light simultaneously mixed results in yellow
You see light that is about 550 nanometers and both your red and green cone cells fire to create yellow
Understand the details of the research design in the Tong et al paper and be able to relate the particulars of the experiment to the research question.
What was the evidence from the study that convinced the researchers that binocular rivalry is resolved before extrastriate cortex?
The study used fMRI to study whether activity in the extrastriate cortex is correlated to visual awareness during binocular rivalry and whether activity changes during rivalry might be comparable to those found during nonrivalrous stimulus alternation
IF RESPONSES EQUIVALENT then resolved before it hits the extrastriate cortex
Graphs below prove that is true
What is the auditory pathway?
AUDITORY PATHWAY:
1. Sound waves enter the auditory canal of the outer ear
- Vibrations hit the eardrum
- The eardrum vibrates, passing on those vibrations to the middle ear
- Bones in the middle ear transfer vibrations transfer the vibrations to the inner ear
5a. Vibrations in the liquid in the cochlea jiggles basilar membrane
5b. The hair cells are bent as a result against the tectorial membrane because the basilar membrane pushes them up which releases an action potential (stereocilia: protein filaments that brush up against the tectorial membrane)
A. Being of stereociia causes a MECHANICAL opening of the hair cell
B. Positively charged potassium ions enter and depolarize the cell
C. This opens voltage gated channels to open, allowing calcium ions to enter the cell
D. triggers the release of neurotransmitters at the bottom of the cell
5c. Tonopoy: neural response to different frequencies lines up spatially on the basilar membrane
6, 7, 8. Info is sent to the brain stem, the midbrain, and the primary auditory cortex
Be able to point to A1 vs V1 on a brain or brain scan.
Generally speaking (ventral vs dorsal areas), where is information about “what” an visual object or auditory sound is vs “where” a visual object or auditory sound is?
What a visual object/auditory abject: identifying sounds and ventral steam – starts in the temporal lobe and goes to the frontal cortex
Where a visual object/auditory object: localizing sounds, dorsal stream
