Visual attention
Describe the two types of attention
•Overt attention: when you move your eyes to a location and attend to that location
•Covert attention: When you shift your attention without moving your eyes
What is color?
•How our brain interprets different wavelengths of visible light
Describe binocular depth cues, including 2 key terms
•Binocular disparity: the difference in what each eye sees; closer objects create a larger disparity
•Stereoscopic depth perception: depth perception created by binocular disparity
Pitch is mostly based on _______
Loudness is mostly based on ______
Pitch is mostly based on _frequency_
Loudness is mostly based on _amplitude_
Name the 3 main categories of depth cues
Oculomotor
Monocular
Binocular
Name the two forms of guidance of overt attention, and an example of each
Top-down processing: knowledge, expectations,task and goals, schemas
Bottom-up processing: visual salience based on things like color, contrast, motion, orientation
What is color constancy, and what are 2 ways we achieve it?
•Color constancy: even though objects are illuminated by different colors of light, we can still usually tell what an object’s actual color is
•Chromatic adaptation: the eyes adjust to the current illumination
•Memory color: our knowledge about the usual colors of objects helps achieve color constancy
Name and describe the oculomotor depth cues
•Convergence: inward movement of the eyes when we look at nearby objects
•Accommodation: change in shape of the lens
Name and describe the structures of the outer ear
Pinna: part that sticks out of our head
Ear canal: where the wax is
Tympanic membrane: eardrum (at the end of the canal)
What is a physical cause of timbre, and the 2 components of that cause?
The time course of a sound
•Attack: the buildup of sound at the beginning of the tone
•Decay: the decrease in sound at the end of the tone
Describe the different components of eye movements, what they form when considered together, and how they are measured
•Fixation: when your eyes stop and take in information
•Saccade: moving your eyes from one place to another
Together, they form a scanpath: the series of fixations and saccades one makes on a given stimulus
Eye movements are measured using eyetracking
Describe the two mechanisms for color vision (one at the retina, one in the brain)
•Trichromacy: there are 3 types of cones that each prefer different wavelengths: S cones (short wavelengths), M cones (medium wavelengths), L cones (long wavelengths)
•Opponent process theory: color vision is caused by opposing responses generated by blue vs yellow, and red vs green (and white vs black)
Describe the distance scaling equation and what it's used for
Perceived size = perceived distance x visual angle
Used for size constancy (our perception of an object’s size is relatively constant even when we view it from different distances)
Name the steps that the sound signal travels from the hair cells to the brain
Hair cells are where transduction happens -> auditory nerve -> subcortical structures including medial geniculate nucleus -> primary auditory cortex (A1)
Name 3 pieces of evidence for opponent-process theory
1.Color afterimages (like the flag demo)
2. Simultaneous color contrast: similar idea but both colors present at same time
3. Subjective experience: color wheel has two opposite quadrants, red vs green and blue vs yellow
4. Color blindness: most common types are red/green and blue/yellow color blind
5. There are neural cells in the lateral geniculate nucleus of the thalamus that respond in an opponent-process way to the S, M, and L cones
Describe spatial neglect, the circumstances in which we can overcome it, the area that is damaged in it, and the specific stage of attentional processing that is malfunctioning
•Spatial neglect: a neurological condition that causes one to ignore part of the world (Hemispatial neglect: ignoring the left or right half of the world)
•Threatening things can make them notice neglected side, especially when there is less competition from good side
•Spatial neglect is usually caused by parietal damage
•Their preattentive processing is likely intact, but focused attention doesn’t function normally
Describe the two types of color mixing and how they differ
•Subtractive color mixture: both paints still absorb the same wavelengths they did when alone (The only wavelengths reflected by the mixture are those that are reflected by both paints)
•Additive color mixture: when light is shined onto a white surface, all the wavelengths are reflected back to our eye (All the light gets added up in our eye—no absorbing is happening)
Name and describe 5 monocular cues
(There are 9 total to choose from)
Pictorial cues:
•Occlusion: closer objects block further away objects
•Relative height: further objects tend to be closer to horizon
•Familiar size: judging distance of objects based on known size
•Perspective convergence: parallel lines appear to come together as they get further away
•Atmospheric perspective: things that are further away are blurrier and have more of a blue tint
•Texture gradient: textures appear to get closer together as they are further away
•Shadows: shadow locations can help us determine their distance
Movement-based cues:
•Motion parallax: when we are moving, closer objects appear to move faster
•Deletion and accretion: during movement, some objects get hidden behind others (deletion) and some get revealed by getting uncovered (accretion)
Name the structures in the middle ear
- Ossicles: malleus, incus, stapes
- Oval window
Name one example of the effects of knowledge (or inference) on perception for:
Visual attention
Color
Depth
Size
Visual attention: top-down guidance by knowledge (e.g., scene schema violation)
Color: color constancy, lightness constancy, shadow perception, memory color
Depth: all depth perception is inference based on depth cues, all monocular cues are based on knowledge
Size: relative size
Name 5 things that covert attention does
Covert attention alters appearance (more colorful, brighter, sharper, etc)
Covert attention alters which brain regions are involved in processing visual information
Covert attention influences retinotopic map activation
Covert attention shifts receptive fields
Covert spatial attention is likely involved in deciding where to move our eyes
Describe the 5 types of colorblindness
Neural:
•Cerebral achromatopsia: lack of color vision from brain damage
Retinal:
•Monochromats: missing 2 or 3 of the 3 cone types, total color blindness
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•Dichromats: more standard colorblindness, 1 of the cone types is missing or malfunctioning, which include:
•Protanope: long (L) cone not functional
•Deuteranope: medium (M) cone not functional
•Tritanope: short (S) cone not functional
Name the components of reichardt detectors, and the limits to what each reichardt detector can detect
Components:
- 2 spatially selective neurons (i.e., different spatial receptive fields)
- delay unit neuron
- comparator neuron
Limits: Each Reichardt detector circuit can only detect one direction of motion, and is tuned to a specific speed (velocity)
Starting from the oval window, describe the steps of turning sound into electrical energy
Oval window vibrations makes waves in the liquid inside cochlea, which makes the basilar membrane start moving, which makes the organ of Corti move up and down and the liquid around the hair cells move, which bends the stereocilia and causes transduction
Name the brain regions responsible for eye movements, motion, color, pitch perception, and spatial neglect
Eye movements: superior colliculus
Motion: Area MT
Color: Area V4
Pitch perception: Area A1
Spatial neglect: parietal lobe