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BPSY 50: Chapter 3 Cheat Sheet (DRAFT) by

Intro To Psychology for freshmen

This is a draft cheat sheet. It is a work in progress and is not finished yet.

SENSATION & PERCEPTION

Sensation
- the activation of receptors in the various sense organs.
* Sensory Receptors - specia­lized forms of neurons.
Sensory Thresholds
1. Just noticeable difference (jnd or the difference threshold) - the smallest difference between two stimuli that is detectable 50 percent of the time.
2. Absolute threshold - the smallest amount of energy needed for a person to consci­ously detect a stimulus 50 percent of the time it is present.
Sense Organs:
- eyes
– ears
– nose
– skin
– taste buds

Examples of Absolute Threshold

Subliminal Sensation

Subliminal stimuli - stimuli that are below the level of
conscious awareness.
– Just strong enough to activate the sensory receptors but not
strong enough for people to be consci­ously aware of them.
– Limin - "­thr­esh­old­"
– Sublimin - "­below the thresh­old."
– Supral­iminal "­above the thresh­old."

Subliminal perception – process by why subliminal
stimuli act upon the uncons­cious mind, influe­ncing
behavior

Habitu­ation & Sensory Adaptation

Habitu­ation - tendency of the brain to stop attending to constant, unchanging inform­ation.
Sensory adaptation - tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging
Micros­accades - constant movement of the eyes, tiny
little vibrations called that people do not notice
consci­ously; prevents sensory adaptation to visual
stimuli.

Psycho­logical Aspects to Light

- Determined by the amplitude of the wave—how high or how low the wave actually is.
Brightness
- is determined by the length of the wave.
Color or Hue
- refers to the purity of the color people see; mixing in black or gray would also lessen the satura­tion.
Saturation
The higher the wave, the brighter the light will be. Low
waves are dimmer.

Long wavele­ngths are found at the red end of the visible
spectrum (the portion of the whole spectrum of light that is visible to the human eye), whereas shorter wavele­ngths are found at the blue end

Figure 3.1 The Visible Spectrum

The wavele­ngths that people can see are only a small part of the whole
electr­oma­gnetic spectrum.

Structure of the Eye

Cornea
- clear membrane that covers the surface of the eye; protects the eye and is the structure that focuses most of the light coming into the eye
Radial kerototomy
- vision­-im­proving technique that uses this fact by making small incisions in the cornea to change the focus in the eye.
Aqueous humor
- next visual layer; clear, watery fluid that is contin­ually replen­ished and supplies nouris­hment to the eye.
Pupil
- hole through which light from the visual image enters the interior of the eye.
Iris
- round muscle (the colored part of the eye) in which the pupil is located; can change the size of the pupil, letting more or less light into the eye; helps focus the image.
Lens
- another clear structure behind the iris, suspended by muscles; finishes the focusing process begun by the cornea.
Retina
- final stop for light in the eye.
 
Contains 3 layers: Ganglion cells, Bipolar cells, and Photor­ece­ptors that respond to various light waves
Rods
- visual sensory receptors found at the back of the retina, respon­sible for noncolor sensit­ivity to low levels of light
Cones
- visual sensory receptors found at the back of the retina, respon­sible for color vision and sharpness of vision.
Blind Spot
- area in the retina where the axons of the three layers of retinal cells exit the eye to form the optic nerve, insens­itive to light.

Figure 3. 2 Structure of the Eye

Light enters the eye through the cornea and pupil. The iris controls the size of
the pupil. From the pupil, light passes through the lens to the retina, where it is
transf­ormed into nerve impulses. The nerve impulses travel to the brain along
the optic nerve.

Figure 3.3 The Parts Of the Retina

(a) Light passes through ganglion and bipolar cells until it reaches and stimulates the
rods and cones. Nerve impulses from the rods and cones travel along a nerve pathway
to the brain. (b) On the right of the figure is a photom­icr­ograph of the long, thin rods and
the shorter, thicker cones; the rods outnumber the cones by a ratio of about 20 to 1.

Figure 3.4 Crossing of the Optic Nerve

The optic nerve tissue from both eyes joins together to form the left optic tract before going on to the left occipital lobe. For the left visual field (shown in blue), the messages from both right sides of the retinas will travel along the right optic tract to the right visual cortex in the same manner.

How the eyes work

- the recovery of the eye’s sensit­ivity to visual stimuli in darkness after exposure to bright lights.
Dark adaptation
- the recovery of the eye’s sensit­ivity to visual stimuli in light after exposure to darkness.
Light Adaptation
- theory of color vision that proposes three types of cones: red, blue, and green.
Trichr­omatic theory
- images that occur when a visual sensation persists for a brief time even after the original stimulus is removed.
Afteri­mages
- theory of color vision that proposes four primary colors with cones arranged in pairs: red and green, blue and yellow.
Oppone­nt-­process Theory Lateral geniculate nucleus (LGN) of thalamus
- either have no cones or have cones that are not working at all
Monochrome colorb­lin­dness
- either the red or the green cones are not working.
Red-green Colorb­lin­dness
– lack of functi­oning red cones.
Protanopia
- lack of functi­oning green cones.
Deuter­anopia
- lack of functi­oning blue cones.
Tritanopia
COLOR BLINDNESS IS SOMETIMES DUE TO SEX-LINKED INHERI­TANCE

SOUND

• Wavelength – interp­reted as frequency or pitch (high,
medium, or low).
• Amplitude – interp­reted as volume (how soft or loud a
sound is).
• Purity – interp­reted as timbre (a richness in the tone
of the sound).
• hertz (Hz) - cycles or waves per second, a
measur­ement of frequency.
A decibel is a unit of measure for loudness.

Structure Of the Ear

- short tunnel that runs from the pinna to the eardrum (tympanic membrane)
Auditory Canal
- thin section of skin that tightly covers the opening into the middle part of the ear, just like a drum skin covers the opening in a drum.
Eardrum
 
- When sound waves hit the eardrum, it vibrates and causes three tiny bones in the middle ear to vibrate.
 
• Hammer • Anvil • Stirrup
- snail-­shaped structure of the inner ear that is filled with fluid
Cochlea
- rests in the basilar membrane; contains receptor cells for sense of hearing.
Organ of Corti
- bundle of axons from the hair cells in the inner ear; receives neural message from the organ of Corti.
Auditory Nerve

Figure 3.8 (conti­nued)

(c) The inner ear. Large spaces are filled with fluid (shown in purple) that vibrates as the oval
window vibrates. (d) A close-up view of the basilar
membrane (in dark pink) with the hair cells of the organ of Corti (in lighter pink). Notice the axons
(small green lines) leaving the hair cells to form the auditory nerve.

Theories Of Pitch

- psycho­logical experience of sound that corres­ponds to the frequency of the sound waves; higher freque­ncies are perceived as higher pitches.
Pitch
- theory of pitch that states that different pitches are experi­enced by the stimul­ation of hair cells in different locations on the organ of Corti.
Place Theory
- theory of pitch that states that pitch is related to the speed of vibrations in the basilar membrane volley principle theory of pitch that states that freque­ncies above 100 Hz cause the hair cells (auditory neurons) to fire in a volley pattern, or take turns in firing.
Frequency Theory
- theory of pitch that states that freque­ncies above 100 Hz cause the hair cells (auditory neurons) to fire in a volley pattern, or take turns in firing.
Volley Principle

TYPES OF HEARING IMPAIR­MENTS

Conduction hearing impairment
- damaged eardrum (which would prevent sound waves from being carried into the middle ear properly), or
 
- damage to the bones of the middle ear (sounds cannot be conducted from the eardrum to the cochlea).
Nerve hearing impairment
- damage in the inner ear, or
 
- damage in the auditory pathways and cortical areas of the brain.
Surgery to help restore hearing
- Cochlear Implant
 
- a microphone implanted just behind the ear picks up sound from the surrou­nding enviro­nment.
(a) In a cochlear implant, a microphone implanted just behind the ear picks up sound from the surrou­nding
enviro­nment. A speech processor, attached to the implant and worn outside the body, selects and arranges the sound picked up by the microp­hone. The implant itself is a transm­itter and receiver, converting the signals from the speech processor into electrical impulses that are collected by the electrode array in the cochlea and then sent to the brain.

TASTE

• Five Basic Tastes:
– Sweet
– Sour
– Salty
– Bitter
– "­Bro­thy­"

• Taste buds
– Taste receptor cells in mouth; respon­sible for sense of taste
• Gustation
– The sensation of a taste.

Figure 3.10 The tounge & Taste buds

(b) The taste bud is located inside the papillae and is composed of small cells that send signals to
the brain when stimulated by molecules of food.

Figure 3.10 (conti­nued)

(c) Microp­hot­ograph of the surface of the tongue, showing two different sizes of papillae. The taste
buds are located under the surface of the larger red papillae, whereas the smaller and more
numerous papillae form a touch-­sen­sitive rough surface that helps in chewing and moving food
around the mouth.

SMELL

– Sense of smell.
Olfaction (olfactory sense)
- Areas of the brain located just above the sinus cavity and just below the frontal lobes that receive inform­ation from the olfactory receptor cells
Olfactory Bulbs
 
At least 1,000 olfactory receptors.

Figure 3.11 The Olfactory Receptors

a) A cross section of the nose and mouth. This drawing shows the nerve fibers inside
the nasal cavity that carry inform­ation about smell directly to the olfactory bulb just
under the frontal lobe of the brain (shown in green).

Figure 3.11 (conti­nued)

(b) A diagram of the cells in the nose that process smell. The olfactory bulb is on top. Notice the
cilia, tiny hairlike cells that project into the nasal cavity. These are the receptors for the sense of
smell.

SOMEST­HETIC SENSES

- the body senses consisting of the skin senses, the kinest­hetic sense, and the vestibular senses.
Somest­hetic Senses
- Means "­bod­y"
Soma
– feeling
Esthetic
- the sensations of touch, pressure, temper­ature, and pain.
Skin senses
- pain signals must pass through a "­gat­e" located in the spinal cord.
Gate-c­ontrol theory
- sense of the location of body parts in relation to the ground and each other.
Kinest­hetic sense
 
– Propri­oce­ptive receptors (propr­ioc­eptors)
- the sensations of movement, balance, and body position sensory conflict theory an explan­ation of motion sickness in which the inform­ation from the eyes conflicts with the inform­ation from the vestibular senses, resulting in dizziness, nausea, and other physical discom­forts.
Vestibular senses
When people grasp two braided pipes–one with cold water running through it, the other with warm water–the sensation is "very hot" and painful.

Perception & Consta­ncies

• Perception
– The method by which the sensations experi­enced at any given moment are interp­reted and organized in some meaningful fashion.
• Size constancy
– The tendency to interpret an object as always being the same actual size, regardless of its distance.
• Shape constancy
– The tendency to interpret the shape of an object as being constant, even when its shape changes on the retina.
• Brightness constancy
– The tendency to perceive the apparent brightness of an object as the same even when the light conditions change.
• Size constancy
- The tendency to interpret the size of an object as being constant, even when its shape changes on the retina.

Gestalt Principles

• Figure­–ground
– The tendency to perceive objects, or figures, as existing on a backgr­ound.
• Reversible figures
– Visual illusions in which the figure and ground can be reversed.
• Similarity
– The tendency to perceive things that look similar to each other as being part of the same group.
• Proximity
– The tendency to perceive objects that are close to each other as part of the same grouping.
• Closure
– The tendency to complete figures that are incomp­lete.
• Continuity
– The tendency to perceive things as simply as possible with a continuous pattern rather than with a complex, broken-up pattern.
• Contiguity
– The tendency to perceive two things that happen close together in time as being related.

Figure 3.16 Gestalt principles of grouping

Develo­pment Of Perception

• Depth perception - the ability to perceive the world in three dimens­ions.
• Studies of depth perception – Visual cliff experi­ment.
• Monocular cues (pictorial depth cues) – cues for perceiving depth based on one eye only.
– Linear perspe­ctive – the tendency for parallel lines to appear to converge on each other.
– Relative size - perception that occurs when objects that a person expects to be of a certain size appear to be small and are, therefore, assumed to be much farther away.
– Interp­osition (overlap) - the assumption that an object that appears to be blocking part of another object is in front of the second object and closer to the viewer.
• Aerial perspe­ctive - the haziness that surrounds objects that are farther away from the viewer, causing the distance to be perceived as greater.
• Texture gradient - the tendency for textured surfaces to appear to become smaller and finer as distance from the viewer increases.
• Motion parallax - the perception of motion of objects in which close objects appear to move more quickly than objects that are farther away.
• Accomm­odation - as a monocular clue, the brain’s use of inform­ation about the changing thickness of the lens of the eye in response to looking at objects that are close or far away.

• Binocular cues - cues for perceiving depth based on both eyes.
– Conver­gence - the rotation of the two eyes in their sockets to focus on a single object, resulting in greater conver­gence for closer objects and lesser conver­gence if objects are distant.
– Binocular disparity - the difference in images between the two eyes, which is greater for objects that are close and smaller for distant objects.

Perceptual Illusions

The Herman grid
– is possibly due to the response of the primary visual cortex.
Müller­-Lyer illusion
- illusion of line length that is distorted by inward­-tu­rning or outwar­d-t­urning corners on the ends of the lines, causing lines of equal length to appear to be different.
Moon illusion
– the moon on the horizon appears to be larger than the moon in the sky.
 
- Apparent distance hypothesis
Autoki­netic Effect
- a small, stationary light in a darkened room will appear to move or drift because there are no surrou­nding cues to indicate that the light is not moving.
strobo­scopic motion
- seen in motion pictures, in which a rapid series of still pictures will appear to be in motion.
phi phenomenon
- lights turned on in a sequence appear to move.
Rotating Snakes
– is due in part to eye movements.
The Enigma
- are due in part to micros­accades
 
- Ame’s room illusion

Factors that Influence Perception

- the tendency to perceive things a certain way because previous experi­ences or expect­ations influence those percep­tions.
Perceptual set (perce­ptual expect­ancy)
- the use of preexi­sting knowledge to organize individual features into a unified whole.
Top-down processing
- the analysis of the smaller features to build up to a complete percep­tion.
Bottom-up processing

Figure 3.8 structure of the ear

(a) This drawing shows the entire ear, beginning with the outer ear (pinna, ear canal, and
eardrum). The vestibular organ includes the semici­rcular canals and the otolith organs (inside the
round structures just above the cochlea). (b) The middle ear. Sound waves entering through the
ear canal cause the eardrum to vibrate, which causes each of the
three bones of the middle ear to vibrate, amplifying the sound.