nsci 225 learning check 02

not consciously perceiving a visual stimulus but being able to process it - some connections from the lgn go to other extra- striate areas are still in tact, allowing them to process it

using methods in order to see what part of the primary visual cortex is most active in response to visual fields - as you go further out in the periphery of visual fields, the less processing space is used - mapped backwards and upside down

the fovea is overrepresented in the pvc

different types of columns represent somewhere in the visual field - location columns, orientation columns, ocular dominance column

every cell within the location column responds to the same receptive field location, responding to stimuli from the same area on the retinotonic map

located within the location column - responds to different orientations of line - each layer in the column responds to the same orientation but as you move to the next column it'll be a different orientation

located within the location column - the first part of the visual pathway where there are binoculars cells - left columns and right columns (because although they're binocular, they have preferences, what side of the visual field they prefer to respond to)

the same thing as a location column but stresses that there's other subtypes of columns within the location column

striped patterns used to study cells in v1 - an array of stripes will activate many feature detectors

firing rate to grating decreases when the stimulus is there for a long time or is repeated (ex: after looking at strong grating of vertical lines for a long time, it will be harder to see gratings because you've adapted)

no, because there's no binocular cells!

the ability of visual information learned through one eye to be accessible and utilized by the other eye (looking at fat lines and skinny lines in one eye and changing to the other eye and seeing lines look weird)

shape of receptive fields gets more specific, location gets less specific

studied the v4 and v5 in participants looking at color versus grayscale and movement versus stillness - found that v4 is active for color displays and v5 is active for moving displays

neurons that respond to different stimuli, dealing with object recognition and categorization

the brain is organized into specialized regions that process specific types of information independently while still interacting with other areas

ventral pathway; connects to the inferotemporal cortex/temporal lobe - determines object identity - is conscious

dorsal pathway; connects to the parietal lobe - determines object location - is more subconscious

removed temporal lobe - monkeys would need to pick correct object to get food - damage to what pathway prevented this

removed parietal lobe - monkeys would need to pick food closest to an object - damage to where/how pathway prevented this

two processes controlled by separate parts of the brain

had agnosia due to damage in temporal lobe, making her unable to identify objects or even describe orientation - could put the card in the slot and pick up objects (where/how pathway is okay)

had agnosia where he could not identify objects but could reason his way to figuring it out about their size and shape (how pathway used)

deficit in the visual control of reaching and other movements - damage to where/HOW pathway

had bilateral parietal damage, causing optic ataxia - performed poorly when trying to pick up the rock

determining the object that caused an image on the retina

1. early vision
2. mid-level vision
3. high-level vision

detecting and combining features (grouping)

constructing surfaces and then objects in 3D space - depth comes into play here

fundamental ambiguity between size and distance - we need cues to understand what is causing the image

depth perception that can happen with one eye - occlusion, familiar and relative size, relative height

cues from intraocular and extraocular muscles

our eyes are separated by about 6cm and the stereoscopic image is the combination of the different views

accommodation and blur - intraocular muscles are responsible for adjusting the shape of the lens

convergence

extraocular eye muscle cue - your eyes move in different directions to look at things - your brain can figure out what direction your eyes are moving and use that information to determine where the object is for depth - is binocular

intraocular muscles adjust the shape of the lens - the muscles tense up for closer items - is monocular

points that would overlap if you put one retina over the other (ex: the fovea) - anything on the horopter

imaginary semicircle - shows everything that is the same distance from whatever you're focusing on (whatever your fovea is directed towards) along the imaginary line - everything on the horopter lays on corresponding points on the retina - there is disparity when the point falls in front of or behind the horopter

the difference between what each eye sees - more disparity the further the object moves away from the horopter - is what gives us stereopsis

things in front of the horopter

things behind the horopter

discovered that binocular dispirit is important for perception - coined stereopsis and the stereoscope

moving a certain shape worth of pixels over by 6 pixels, causing the shape to pop up at you (moving the corresponding points)

how do our brains figure out that objects from different perspectives / images are the same

the fovea

neurons activated by differences in retinal images.

there were few binocular cells and more monocular cells, causing a lack of stereopsis

seeing how far an object is from another object

seeing how far a distance is

one object partially hidden by another is perceived as being further away - relative monocular cue

when two objects are assumed to be the same size, the one appearing larger on your retina is perceived as closer (ex: two cans) - relative cue

knowing how large an object actually is gives you a cue to depth - absolute cue

absence of light - relative cue

we are used to the light source coming from above

particles in the atmosphere cause objects that are further away to look blurry

the density of a texture's gradient increases with distance

the processing of several aspects of a problem simultaneously; contrasts with the step-by-step (serial) processing of most computers

identifying objects by a unique feature - classes of objects are identified by shape

more vertical and horizontal lines in the environment, when one object is blocked it comes out the other side, light from above assumption

meaning of a scene, scene schema (knowledge of what belongs in a scene)

the same blob is interpreted as whatever would fit into the scene schema - top-down processing

sensation: bottom-up processing
perception: our interpretations of the bottom-up processing

saw a face with the left eye and a house with the right eye - press a button anytime their perception changed - both areas are the same for sensation but for measuring PERCEPTION the ffa and ppa were activated more based on what they were focusing on

people were able to train and learn to recognize greebles, showing an increase activation in their ffa - the ffa is activated by anything that needs high levels of visual detail for differentiation

what wavelengths an object absorbs is not seen and what an object reflects is seen (cardinals reflect red wavelengths and absorb the rest)

shows the contribution of each wavelength for light reflecting off an item - is never really a peak at one wavelength because everything is a mixture - assumed white ambient lighting

used for any kind of pigment - what wavelengths are visible is determine by whatever is left after two colors are mixed is what they have in common - they absorb each others' pigments

used for any kind of light - primary colors are green, red, and blue lights - ends up with white if you combine all three because its all of the wavelengths combined equally

justice for Maxwell who also deserves credit - participants given 3 different adjustable colors of lights (red green and blue) to try to match the target light color - later revealed that we have the three different types of cones

stumble that are perceptually the same but physically different (different combinations of wavelengths to make green vs. pure green are perceptually the same bc they're activating the cones in the same way but have different wavelength amounts)

we cannot tell color with a single cone - we need to compare the firing of different cones to get information on the brightness and the color - a rod can respond the same amount to a dim light near the peak wavelength and a bright light far away from the peak

no working cones - bad foveal vision, reduced visual acuity, hypersensitivity to light because you can't switch to cone vision

one working cone - good visual acuity, only sees shades of grey and differences in brightness

two types of working cones - missing one cone

dots that show if you're colorblind?

phenomenological report of the color wheel - color vision comes from 4 primary chromatic color pairs - evidence: opponent neurons, color afterimages, hue cancellation

opponent-procesing theory based on what afterimages appear

the bending of light by the lens; the more contracted the ciliary muscles, the thicker the lens, the more the zone fibers can relax, the more refraction occurs, the closer you can see

receives visual sensory input

internal copy of a motor command, uses this information combined with visual input to understand when you are seeing depth

parallel lines appear to come together in the distance

the perceived length of a line on a railroad is affected by linear perspective cues

illusory perception of depth from color

higher objects are seen as more distant - monocular cue

depth cue where objects closer appear to pass faster and objects further appear to pass slower

a perception not made from an actual sensation, illusory border

we tend to continue lines/objects

interpretation of pictures in a way makes the most sense based on logic

grouping objects with similar properties

grouping objects positioned close to one another

grouping objects that move in the same direction

grouping objects that appear familiar or meaningful

elements within the same region of space are grouped together

a connected region of the same visual properties are perceived as a unit

visual events that occur at the same time are perceived as belonging together (flashing color lights)

surface completed behind something even though obscured

vase vs. face illusion - figure is more thing like and ground is more abstract - the contour separating the two things belongs to he figure

lower position in the visual field - (left or right makes no difference) - convexity - symmetry - smaller area size - vertical or horizontal orientations - familiarity

things that are bubbling out appear to be the figure

shapes that are symmetrical appear to be the figure

being able to tell that something is the same color in different lighting conditions

chromatic adaptation, effects of the surroundings, memory and previous experience

we adapt to whatever our ambient lighting is to achieve color constancy, works best if we are in the same ambient lighting as the object we are perceiving

color constancy works best when an object is surrounded by many colors

consistent brightness is perceived when lighting conditions change

when the difference in light reflecting is due to a shadow and not an actual color difference

an actual color difference

familiar shapes, nature of the shadow/contours (is there a penumbra?),