PSYCH // CHAPTER 4

Optic Nerve

A bundle of ganglion axons that carry visual information to the brain.

Adaptation

is an adjustment in sensory capacity after prolonged exposure to unchanging stimuli. - it occurs as people become accustomed to a stimulus and change their frame of reference.

Pitch

is the characteristic that makes sound seem "high" or "low."

Frequency

is the number of wave cycles that occur in a second.

Eardrum

is the part of the ear that vibrates when sound waves hit it. The more intense the sound, the more this part vibrates.

Retina

is the part of the eye that converts the electromagnetic energy of light to electrical impulses for transmission to the brain.

Inner Ear

is the portion of the ear that changes the sound vibrations into a form in which they can be transmitted to the brain.

Absolute threshold

is the smallest intensity of a stimulus that must be present for it to be detected.

Weber's Law

states that a just noticeable difference is a constant proportion of the intensity of an initial stimulus (rather than a constant amount). -Weber's law helps explain why a person in a quiet room is more startled by the ringing of a cellphone than is a person in an already noisy room.

Sensation

the activation of the sense organs by a source of physical energy.

Dark Adaptation

the phenomenon of adjusting to dim light after being in brighter light. -Although the cones reach their greatest level of adaptation in just a few minutes, the rods take 20 to 30 minutes to reach the maximum level.

Light Adaptation

the process of adjusting to bright light after exposure to dim light—occurs much faster, taking only a minute or so.

Perception

the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events. (Book Define) the sorting out, interpretation, analysis, and integration of stimuli carried out by the sense organs and brain.

Olfactory cells

the receptor neurons of the nose.

Psychophysics

the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them

Otoliths

tiny, motion-sensitive crystals in the semicircular canals.

The pull on our bodies caused by the acceleration of forward, backward, or up-and-down motion, as well as the constant pull of gravity, is sensed by the...

Otoliths

Hair Cells

Tiny cells covering the basilar membrane that, when bent by vibrations entering the cochlea, transmit neural messages to the brain

Cochlea

a coiled tube that looks something like a snail and is filled with fluid that vibrates in response to sound.

Rhodopsin

a complex reddish-purple protein whose composition changes chemically when energized by light.

Middle Ear

a tiny chamber containing three bones (the hammer, the anvil, and the stirrup).

Auditory Canal

a tube-like passage that leads to the eardrum.

Stimulus

any passing source of physical energy that produces a response in a sense organ.

Feature detectors

are extraordinarily specialized neurons that are activated only by visual stimuli having particular features, such as a particular shape or pattern.

Visual Illusions

are physical stimuli that consistently produce errors in perception.

Rods

are thin, cylindrical receptor cells that are highly sensitive to light. - related to vision in dimly lit situations and are largely insensitive to color and to details as sharp as those the cones are capable of recognizing. - play a key role in peripheral vision—seeing objects that are outside the main center of focus—and in night vision.

Cones

are typically cone-shaped, light-sensitive receptor cells that are responsible for sharp focus and color perception, particularly in bright light. - Relate to color vision. - primarily responsible for the sharply focused perception of color, particularly in brightly lit situations.

Noise

as defined by psychophysicists, is background stimulation that interferes with the perception of other stimuli.

Pheromones

chemicals they secrete into the environment that produce a social response in other members of the same species.

Stimulation of the nerve cells in the eye triggers a neural response that is transmitted to other nerve cells in the retina called...

Bipolar cells & Ganglion cells.

Inside The Eye

(1) Ray of light being reflected off an object first travels through the CORNEA, a transparent protective window. (2) The cornea, because of its curvature, bends (or REFRACTS) light as it passes through, playing a primary role in focusing the light more sharply. After moving through the cornea, the light traverses the pupil. (3) The PUPIL is a dark hole in the center of the IRIS, the colored part of the eye, which in humans ranges from a light blue to a dark brown. (4) The size of the pupil opening depends on the amount of light in the environment. (5) The dimmer the surroundings are, the more the pupil opens to allow more light to enter. (6) Having traveled through the pupil and lens, the image of the tree finally reaches its ultimate destination in the eye: the RETINA.

Inside the Ear

(1) Sounds, arriving at the outer ear in the form of wavelike vibrations, are funneled into the auditory canal which leads to the eardrum. (2) The ear vibrates upon receiving sound waves. (3) These vibrations are then transferred into the middle ear that transmits vibrations to the oval window, a thin membrane leading to the inner ear. (4) Because the hammer, anvil, and stirrup act as a set of levers, they not only transmit vibrations but also increase their strength. Moreover, because the opening into the middle ear (the eardrum) is considerably larger than the opening out of it (the oval window), the force of sound waves on the oval window becomes amplified. (5) The middle ear, then, acts as a tiny mechanical amplifier. (6) When sound enters the inner ear through the oval window, it moves into the cochlea.

Basilar Membrane

(Inside the cochlea) a structure that runs through the center of the cochlea, dividing it into an upper chamber and a lower chamber.

Module 10 // Sensing the World Around Us

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Module 11 // Vision: Shedding Light on the Eye

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Module 12 // Hearing and the Other Senses

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Module 13 // Perceptual Organization: Constructing Our View of the World

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Low Frequency vs High Frequency

- At very low frequencies there are relatively few wave cycles per second. These cycles are visible to the naked eye as vibrations in the speaker. - Low frequencies are translated into a sound that is very low in pitch. - Higher frequencies are heard as sounds of a higher pitch. - At the upper end of the sound spectrum, people can detect sounds with frequencies as high as 20,000 cycles per second.

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- Bipolar cells receive information directly from the rods and cones and communicate that information to the ganglion cells. - The ganglion cells collect and summarize visual information, which is then moved out the back of the eyeball and sent to the brain through a bundle of ganglion axons called the optic nerve.

Fovea

- Cones are concentrated on this part of the retina. - Particularly sensitive region of the retina.

Vision

- Starts with light, the physical energy that stimulates the eye. - Light is a form of electromagnetic radiation waves that are measured in wavelengths. - The sizes of wavelengths correspond to different types of energy.

About the retina

- The retina consists of a thin layer of nerve cells at the back of the eyeball. - There are two kinds of light-sensitive receptor cells in the retina. Cones & Rods. - The rods and cones are distributed unevenly throughout the retina.

Stimuli

- They vary in both type and intensity. Different types activate different sense organs. - Ex. We can differentiate light stimuli (which activate the sense of sight and allow us to see the colors of a tree in autumn) from sound stimuli (which, through the sense of hearing, permit us to hear the sounds of an orchestra).

Opponent-process Theory of Color Vision

- This was first proposed by German physiologist Ewald Hering in the 19th century, receptor cells are linked in pairs, working in opposition to each other. - There are a blue-yellow pairing, a red-green pairing, and a black-white pairing. - If an object reflects light that contains more blue than yellow, it will stimulate the firing of the cells sensitive to blue, simultaneously discouraging or inhibiting the firing of receptor cells sensitive to yellow—and the object will appear blue. - If, in contrast, a light contains more yellow than blue, the cells that respond to yellow will be stimulated to fire while the blue ones are inhibited, and the object will appear yellow.

Trichromatic Theory of Color Vision

- This was first proposed by Thomas Young and extended by Hermann von Helmholtz in the first half of the 1800s. - This theory suggests that there are three kinds of cones in the retina, each of which responds primarily to a specific range of wavelengths. - One is most responsive to blue-violet colors, one to green, and the third to yellow-red. - perception of color is influenced by the relative strength with which each of the three kinds of cones is activated.

Smell

- We also have a good memory for smells, and long-forgotten events and memories—good and bad—can be brought back with the mere whiff of an odor associated with memory. - The sense of smell is sparked when the molecules of a substance enter the nasal passages and meet olfactory cells, which are spread across the nasal cavity. - It has long been known that nonhumans release pheromones, transmit messages such as an alarm or sexual availability.

Bottom-up Processing

- consists of the progression of recognizing and processing information from individual components of a stimuli and moving to the perception of the whole. - We would make no headway in our recognition of the sentence without being able to perceive the individual shapes that make up the letters. -processing that is initiated by sensory information about the external environment.

Taste

- involves receptor cells that respond to four basic stimulus qualities: sweet, sour, salty, and bitter. - A fifth category also exists, a flavor called umami, which roughly translate to "meaty" or "savory" - there are about 10,000 taste buds where the receptor cells are located.

Amplitude

- is a feature of wave patterns that allows us to distinguish between loud and soft sounds. - the spread between the up-and-down peaks and valleys of air pressure in a sound wave as it travels through the air.

Sound waves

- is the movement of air molecules brought about by a source of vibration. - travel through the air in wave patterns similar in shape to those made in water when a stone is thrown into a still pond.

Gate-control Theory of Pain

- particular nerve receptors in the spinal cord lead to specific areas of the brain related to pain. - When these receptors are activated because of an injury or problem with a part of the body, a "gate" to the brain is opened, allowing us to experience the sensation of pain.

Top-down Processing

- perception is guided by higher-level knowledge, experience, expectations, and motivations. - You were able to figure out the meaning of the sentence with the missing letters because of your prior reading experience and because written English contains redundancies.

Frequency Theory of Hearing

- suggests that the entire basilar membrane acts as a microphone, vibrating as a whole in response to a sound. -the nerve receptors send out signals that are tied directly to the frequency (the number of wave crests per second) of the sounds to which we are exposed, with the number of nerve impulses being a direct function of a sound's frequency. - the higher the pitch of a sound (and therefore the greater the frequency of its wave crests), the greater the number of nerve impulses that are transmitted up the auditory nerve to the brain.

Gestalt Laws of Organization

- these principles were set forth in the early 1900s by a group of German psychologists who studied patterns, or gestalts. - a series of principles that describe how we organize bits and pieces of information into meaningful wholes. - closure, proximity, similarity, and simplicity.

Skin Senses

- touch, pressure, temperature, and pain—play a critical role in survival, making us aware of potential danger to our bodies. - Most of these senses operate through nerve receptor cells located at various depths throughout the skin, distributed unevenly throughout the body. - One explanation for pain is that it is an outcome of cell injury; when a cell is damaged, regardless of the source of damage, it releases a chemical called substance P that transmits pain messages to the brain.

Place Theory of Hearing

- which states that different areas of the basilar membrane respond to different frequencies. - The part of the basilar membrane nearest to the oval window is most sensitive to high-frequency sounds, and the part nearest to the cochlea's inner end is most sensitive to low-frequency sounds

Difference threshold

-the minimum change in stimulation required to detect the difference between two stimuli -the smallest level of added or reduced stimulation required to sense that a change in stimulation has occurred.

Semicircular canals

-which consists of three tubes containing fluid that sloshes through them when the head moves, signaling rotational or angular movement to the brain. -helps with balance.

When does a stimulus become strong enough to be detected by our sense organs?

It often takes a very small stimulus to produce a response in our senses. For example, the sense of touch is so sensitive that we can feel a bee's wing falling on our cheeks when it is dropped from a distance of 1 centimeter.

Visible Spectrum

The range of wavelengths to which the human eye is sensitive.

top down/bottom up

Top-down and bottom-up processing occur simultaneously, and interact with each other, in our perception of the world around us. Bottom-up processing permits us to process the fundamental characteristics of stimuli, whereas top-down processing allows us to bring our experience to bear on perception.