AP Psychology-Sensation & Perception Module 18

Pupil

Adjustable opening in the center of the eye through which light enters

Where are feature detectors located, & what is their function? How do feature detectors work together to portray a "whole" image?

-Specialized neurons in occipital lobes visual cortex that receives info from ganglion cells in retina -Respond to specific features such as angles, edges & movement

Iris

-Ring of muscle tissue that forms the colored portion of the eye around the pupil -Controls the size of the pupil opening

Using fMRI scans, how are we able to tell if a person is looking at a "shoe, chair or face?"

-Based on the pattern of brain activity -Looking at different objects activates different areas of the brain

How does parallel processing help us analyze a visual scene? How would the 4 subdimensions mentioned in the text allow you to see & perceive a person walking toward you on the street?

-Brain divides into subdimensions-motion, form, depth, color & works on each aspect simultaneously

Retina

-Light-sensitive inner surface of the eye, containing rods/cones plus layers of neurons that begin the processing of visual information -Thin, delicate, yellowish, transparent

Optic nerve

-Nerve that carries neural impulses from the eye to the brain -Transfers visual info from retina to visual centers of brain

Explain how Hering's Opponent-process theory adds to the explanation of how we see & perceive color

-Opposing retinal processes(red-green, yellow-blue, white-black) enable color vision. Explains after image effect -Ex:Some cells are stimulated by green & inhibited by red & vice versa

Discuss how the Young-Helmholtz Trichromatic theory explain how we see & perceive color? Then discuss how it explains color blindness

-Theory that retina contains 3 different color receptors-1 sensitive to red, green, & blue-which when stimulated in combination, can produce the perception of any color -Color blindness is due to the failure of 1 color receptor to work alone or w/one another

Cornea

-Transparent layer forming front of eye -Protects eye -Bends light to help focus -Focus entering light rays

What are the 2 physical characteristics of light & how do they determine our awareness of hue & intensity?

-Wavelength-distance from 1 wave peak to the next-determines hue or color -Intensity:Amount of energy in light waves (determined by a waves amplitude or height) determines brightness

Concerning the phenomenon of color blindness, what percentage of people are impacted?

2%

Fovea

Central focal point in the retina, around which the eye's cones cluster

Path of light entering eye

Cornea, pupil, lens, retina, rods/cones, bipolar cells, ganglion cells, blind spot, optic nerve, visual cortex of occipital lobe

Lens

Flexible transparent structure behind the pupil that changes shape to help focus images on the retina

Concerning the phenomenon of color blindness, what subgroup of humans is most impacted?

Males

Blind spot

Point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there

Concerning the phenomenon of color blindness, what is the most common deficiency?

Red-green

Cones

Retinal receptor cells that are concentrated near the center of the retina & that function in daylight or in well-lit conditions -Detect fine detail & give rise to color sensations

Rods

Retinal receptors that detect black, white, & gray; necessary for peripheral & twilight vision, when cones don't respond

Name 3 ways in which rods & cones differ

Rods: -Detect black, white, grey -Useful in night/peripheral vision -Share bipolar cells to send combined messages Cones: -Detect color -Useful in daylight/well-lit areas -Many have their own bipolar cells that relay messages to the visual cortex & help to see finer details

Ganglion cells

Specialized neurons in the retina that connect to the bipolar cells; the bundled axons of the ganglion cells form the optic nerve

Bipolar cells

Specialized neurons that receive information from the retinal cells(rods & cones) & distribute information to the ganglion cells

Why does human vision have a blind spot?

There are no receptor cells where the optic nerve leaves the eye

How does vision in the fovea relate to placement & quantity of rods & cones? How might the experience of nocturnal animals be different from humans with regard to their visual system physiology?

They may have more cones near the fovea, near the retinas area of central focus. Bipolar cells send cones individual messages to the visual cortex. These direct connections preserve the cones precise information, making them better able to detect finer detail

How might parallel processing be related to blindsight?

Visual systems for perception & action illustrate dual processing

How large is the portion of light visible to humans related to the spectrum of electromagnetic energy?

Wavelength between 10^1-10³

Why do we see an afterimage when we look away at a white piece of paper after staring at a yellow & green flag, as in Figure 18.12?

You tire your neural response to the yellow & green colors when we continue to stare at it & then when we stare at the white paper, we see blue because it's the opponent color