AP Psych Unit 3: Sensation and Perception

Module 16 (Flashcards 1-17), Module 17 (Flashcards 18-21), Module 18 (Flashcards 22-48), Module 19 (Flashcards 49-70), Module 20 (Flashcards 71-89), Module 21 (Flashcards 90-111)

Sensation

A process that allows our sensory receptors and nervous system to receive STIMULUS (from the environment)

• Sight, Hearing, Taste, Touch, Smell

Perception

A process of organizing and interpreting sensory information

• allows us to recognize a specific sense

  • EX: Seeing a person and recognizing it as your friend

Bottom-up Processing

Sensory Analysis that emphasizes characteristics of stimuli (rather than our expectations)

• Sensation

• What we first sense

Top-down Processing

Sensory Analysis that emphasizes a person’s expectations, concept memories and other cognitive factors

• Perception —> What we perceive

Selective Attention

Focusing all our conscious awareness on a particular stimulus

• Focusing on one thing and one thing only even though there’s a bunch of things happening around you

Cocktail Party Effect

A person’s ability to attend to one voice among a sea of voices

• Ex: Having a conversation with someone at a loud concert

• Ex: Hearing your name being called even though so many people are making noise around you

Inattentional Blindness

Failing to see visible objects when our attention is directed somewhere

Three basic steps to sensory systems

The senses…

1. Receive sensory stimulation

2. Transform stimulation into neural impulses

3. Deliver neural information to the brain

Transduction

Converting one form of energy to another

• Ex: Sounds —> Neural Impulses our brain can interpret

• IMPORTANT TO KNOW!

Absolute Threshold

The minimum level of stimulation necessary for a stimulus (light, sound, pressure, etc) to be detected

• This “minimum level” has to be detected 50% of the time

Signal Detection Theory

Predicts WHEN and HOW people will detect a faint stimulus amid background noise

• Asks why people respond differently to the same stimulus

• THERE IS NO SINGLE ABSOLUTE THRESHOLD

• Individual thresholds vary

  • May depend on the strength of the stimulus or a person’s experiences, motivations, and alertness

Subliminal

Stimuli that is NOT CONSCIOUSLY DETECTED 50% of the time

• Below the absolute threshold

Priming

People can be affected by stimuli so weak that they don’t even notice it

• we can evaluate a stimulus unconsciously

• subliminal stimuli does not affect our behavior

Difference Threshold

The minimum stimulus difference a person can detect 50% of the time

• Aka “Just Noticeable Difference”

• Ex: Add 1 ounce to 10 ounce, you will notice, add 1 ounce to 100 ounces, you probably will not

Weber’s Law

Two stimuli must differ by a constant percentage (not constant amount)

• The constant percentage depends on the stimulus

• EX: two lights must differ in intensity by 8%

Sensory Adaptation

Diminished (less) sensitivity as a consequence of constant stimuli

• EX: a bad smell “going away” when we get used to it

  • We get used to certain stimuli because our nerve cells don’t fire as often

Perceptual Set

A mental disposition to perceive one thing over another

• We see what we expect to see

Parapsychology

The study of paranormal phenomena

• Includes the study of ESP (extrasensory perception) and psychokinesis

Extrasensory Perception (ESP)

Awareness occurs apart from sensory input

• Telepathy (mind to mind communication), Clairvoyance (perceiving remote events), Precognition (seeing the future)

ESP ISN’T REAL, BUT WHY?

1. To believe in ESP, you must believe the brain is capable of perceiving without sensory input

2. Researchers have been unable to replicate ESP phenomena under controlled conditions

What light energy is visible to humans?

We can see light waves with a frequency of a little less than 400nm and a little more than 700nm

• THIS IS SUPER LITTLE!!!

Lightwave Wavelength

Determines what hue (color) we see

• The distance from one wave peak to the next

Lightwave Amplitude

Determines what brightness (intensity of light) we see

• The height of a lightwave

Cornea

The eye’s clear, protective outer layer covering the pupil and iris

• Light first enters the eye here

Pupil

A small adjustable opening in the center of the eye through which light passes

Iris

A ring of muscle tissue that forms the colored portion of the eye around the pupil

• Controls the size of the pupil opening

  • Dilates or constricts in response to light intensity

• Unique to each person

Lens

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

Accommodation

a process in which the LENS changes its curvature and thickness to focus on light rays

Retina

The light-sensitive inner surface of the eye (located in the back)

• containing the receptor rods and cones that receive incoming lightwaves

• containing layers of neurons that begin the processing of visual information

What happens in the Retina?

1. Lightwaves are transduced into neural impulses by rods and cones

2. Transduced lightwaves are passed to the bipolar and ganglion cells

Rods

Retinal photoreceptors that detect black, white, and gray, and are sensitive to movement

• When cones don’t respond, they are necessary for peripheral and twilight vision

• Have no hotline to the brain

  • They share connections to a single bipolar cell sending a combined message to the brain

Characteristics of Rods

Number	120 Million
Location in Retina	Outer Periphery
Sensitivity in Dim Light	High!!!
Color Sensitivity	Low!!
Detail Sensitivity	Low!!!!

Cones

Retinal photoreceptors that function in daylight or in well-lit conditions and detect fine detail and create color sensations

• In dim light, ______ become unresponsive and we are unable to see color

• Many ______ have their own hotline to the brain:

  • One ______ transmits its message to a single bipolar cell, which relays the message to the visual cortex (where a large area receives input from the fovea)

Characteristics of Cones

Number	6 Million
Location in Retina	Center (cluster in and around the fovea)
Sensitivity in Dim Light	Low!!!
Color Sensitivity	High!!
Detail Sensitivity	High!!!!

Fovea

The central focal point in the retina, around which the eye’s cones cluster

• The area of greatest visual acuity (where focus is sharpest)

  • POINT OF CENTRAL FOCUS

Optic Nerve

This nerve leaves through the back of the eye and carries the neural impulses from the eye to the brain

• Comprised of the axons of the ganglion cells

What happens to the neural impulse after it exits the eye?

The optic nerve carries the impulse to the thalamus and on to the visual cortex of the occipital lobes

Blindspot

The point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells (rods or cones) are located there

Young-Helmholtz trichromatic (three color) theory

The theory that the retina contains three different types of color receptors (cones) — one most sensitive to red, one to green, one to blue

• When stimulated in combination, the three color receptors can produce the perception of any color

Characteristics of Color Blindness

• About 1 person in 50 is color blind

• Males are more affected since the defect is genetically sex-linked

• Most people are not actually blind to all colors

  • They simply lack functioning red- or green-sensitive cones, or sometimes both

• Vision is monochromatic (one color) or dichromatic (two-color)

  • seems ‘normal’ to color blind people

Hering Opponent-Process theory

The theory that cone photoreceptors are paired together (red-green, blue-yellow, white-black) to enable color vision

• Activation of one color of the pair inhibits the activation of the other

  • EX: some cells are stimulated by green and inhibited by red (and vice versa)

How does Color Processing occur?

1. The retina’s red, green, and blue cones respond in varying degrees to different color stimuli, as the Young-Helmholtz trichromatic theory suggests

2. The cones responses are then processed by opponent-process cells (red vs green, blue vs yellow, black vs white), as Hering’s opponent-process theory proposed.

Feature Detectors

Nerve cells located in the visual cortex of the occipital lobe that respond to a scene’s edges, lines, angles and movements

What do Feature Detectors do?

Receives information from individual ganglion cells in the retina and pass it to other cortical areas, where supercell clusters respond to more complex patterns

Parallel Processing

The act of thinking about many aspects of a problem simultaneously

• The brain’s natural mode of information processing for many functions, including vision

How does Parallel Processing operate?

The brain splits the work of processing motion, form, depth, and color to different areas.

After taking a scene apart, the brain integrates these subdimensions into the (one whole) perceived image.

How we recognize faces using Parallel Processing

To recognize a face, your brain integrates information projected by your retinas to several visual cortex areas and compares it with stored information, thus enabling your fusiform face area to recognize the face: Grandmother!

• Some supercells—actually nicknamed grandmother cells—do appear to respond very selectively to 1 or 2 faces in 100

Gestalt Psychology

Focuses on the human ability to perceive overall patterns

• Visual perception is an active creation, not merely the adding up of lines and movement

Figure-Ground

The organization of the visual field into objects (figure) that stand out from their surroundings (ground)

Grouping

The perceptual tendency to organize stimuli into coherent groups

• Principles of Grouping include: Proximity, Continuity, Closure, Similarity

Proximity

The tendency to group nearby figures together

Continuity

The tendency to perceive smooth, continuous patterns over discontinuous patterns

Closure

The tendency to fill in gaps to create a complete, whole object

Depth Perception

The ability to see objects in three dimensions, even if the images that strike the retina are two dimensional

• Allows us to judge distance

Visual Cliff

A laboratory device for testing depth perception in infants and young animals

Binocular Cues

A depth cue that depends on the use of two eyes

• Used to judge the distance of nearby objects

• Contributors: retinal disparity, convergence

Retinal Disparity

A binocular cue for perceiving depth

By comparing retinal images from the two eyes, the brain determines distance

• The greater the disparity (difference) between the two images, the closer the object is

  • You can test this out by holding your finger close to your eyes. Close one eye, then the other eye to see the difference

Convergence

A binocular cue

The degree to which our eyes must turn inwards to allow us to focus on a very close object

Monocular Cues

A depth cue available to each eye separately

• Used to judge the distance and depth of faraway objects

• Contributors: interposition, linear perspective, relative height, relative size, relative motion

Linear Perspective

Parallel lines appear to meet in the horizon

• The sharper the angle of convergence, the greater the perceived distance is

Interposition

If one object partially blocks our view of another, we perceive it as closer

Relative Motion

As we move, objects that appear stable seem to move

• EX: When riding a bus and fixating on the roof of a house, the surroundings around the house will look like they’re moving too

• The farther an object is from a fixation point, the farther it seems to move

• type of monocular cue

Phi Phenomenon

An illusion of movement created when two or more adjacent lights blink on and off in quick succession

Perceptual Constancy

Perceiving objects as unchanging (having consistent color, brightness, shape, and size) even as illumination and retinal images change

Color Constancy

Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

• Since you know that an apple is red, you will perceive it as red no matter what (even in a dark room!)

Brightness / Lightness Constancy

Perceiving a familiar object as having a consistent brightness even as its illumination changes

Shape Constancy

Perceiving a familiar object as having a consistent form even as its moves

Size Constancy

Perceiving a familiar object as having a consistent size even as its distance changes

Perceptual Adaptation

The ability to adjust to changed sensory input, including an artificially displaced or inverted visual field

• EX: Getting a new pair of glasses and having to adjust seeing through them

Audition

The sense or act of hearing

Soundwave Wavelength

Determines what frequency (pitch) we hear

• The distance from one wave peak to the next

Soundwave Amplitude

Determines the perceived loudness we hear

• The height of a wave

The Three Divisions of the Ear

The ear is divided into outer, middle, and inner sections

Auditory Canal

The channel located in the outer ear that funnels sound waves from the pinna (part of the ear we see) to the tympanic membrane (ear drum)

Tympanic Membrane (Ear Drum)

A thin layer of tissue that vibrates in response to sound waves

Ossicles

Transfers the sound wave vibrations from the tympanic membrane to the oval window of the cochlea

• Part of the middle ear section

• Made up of the three smallest bones in the human body, the incus (anvil), the malleus (hammer), and the stapes (stirrup)

Oval Window

Vibrates when it receives sound waves and causes the fluid inside the cochlea to move

• The membrane-covered opening of the cochlea

Cochlea

Sound waves traveling through the cochlear fluid trigger nerve impulses

• A coiled, bony, fluid-filled tube in the inner ear (looks like a snail)

• Contains 16,000 hair cells that allow us to hear

How does transduction occur in the ear?

1. Outer ear funnels sound waves to the eardrum

2. The bones of the middle ear (hammer, anvil, stirrup) amplify and relay the eardrum’s vibrations through the oval window into the fluid-filled cochlea

3. The resulting pressure changes in the cochlear fluid cause the basilar membrane to ripple

   • This bends the hair cells on its surface

4. Hair cell movement trigger impulses at the base of nerve cells

   • The nerve cells’ fibers converge to form the auditory nerve

5. The auditory nerve sends neural messages to the thalamus and on to the auditory cortex

Sensorineural Hearing Loss

Damage to the cochlea’s hair cell receptors or the auditory nerve

• Caused by disease, biological changes (hereditary, aging), prolonged exposure to ear-splitting noise and music

• With auditory nerve damage, people may hear sound but have trouble discerning what someone is saying

Conduction Hearing Loss

Damage to the mechanical system—the eardrum and middle ear bones—that conducts sound waves to the cochlea

• less common than Sensorineural hearing loss

Dangerous levels of sound

As a general rule, any noise we cannot talk over (loud machinery, fans screaming at a sports event, music blasting at maximum volume) may be harmful, especially if prolonged and repeated.

Cochlear Implant

A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea

How does the brain detect LOUDNESS?

A soft, tone activates only the few hair cells attuned to its frequency. Given louder sounds, neighboring hair cells also respond. Thus, the brain interprets loudness from the number of activated hair cells.

Place Theory

Presumes that we hear different pitches because different sound waves trigger activity at different spots along the cochlea’s basilar membrane

• The brain determines a sound’s pitch by recognizing the specific area (on the membrane) that is generating the neural signal

• Explains how we hear HIGH-PITCHED SOUNDS, but not low-pitched sounds

Frequency Theory

The brain reads pitch by monitoring the frequency of neural impulses traveling up the auditory nerve

The whole basilar membrane vibrates with the incoming sound wave, triggering neural impulses to the brain at the same rate as the sound wave. 

If the sound wave has a frequency of 100 waves per second, then 100 pulses per second travel up the auditory nerve.

• Explains how we hear LOW-PITCHED SOUNDS

Volley Principle

By firing in rapid succession, neurons can achieve a combined frequency above 1000 waves per second

• An extension of Frequency Theory

Locating Sounds

Sound waves strike one ear sooner and more intensely than the other. From this information, our nimble brain can compute the sound’s location

Sense of Touch

A mix of four basic and distinct skin senses, pressure, warmth, cold, and pain

• Our other skin sensations are variations of pressure, warmth, cold, and pain.

Somatosensory Cortex

This section of the brain receives incoming sensory information from our skin (TOUCH), as well as other senses.

Pain

A biopsychosocial event

• reflects both bottom-up sensations and top-down cognition

• experiences vary widely, from group to group and from person to person

Biological Pain Influences

Nociceptors (sensory receptors) —mostly in your skin, but also in your muscles and organs—detect hurtful temperatures, pressure, or chemicals

Pain Circuit

Sensory receptors (nociceptors) respond to potentially damaging stimuli by sending an impulse to the spinal cord, which passes the message to the brain, which interprets the signal as pain

• a biological pain influence

Gate-Control Theory

A theory that states that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain

• The “gate” is opened by the activity of pain signals traveling up small nerve fibers (these conduct most pain signals)

• The “gate” is closed by activity in larger fibers (such as massage) or by information coming from the brain (such as distracting thoughts).

Phantom-Limb Pain

The brain’s ability to create pain after a limb amputation

• Without normal sensory input, the brain may misinterpret and amplify spontaneous but irrelevant central nervous system activity

Psychological Pain Influences: Attention

Pain is impacted by how much attention we give to it

• If we distract our minds with other thoughts, the pain feels as if it has diminished

Psychological Pain Influences: Memory

Our memories of pain may be edited from the actual pain we felt.

• People overlook a pain’s duration and recall two moments: pain’s peak moment and how much pain is felt at the end.

Social-Cultural Pain Influences

• We tend to perceive more pain when others seem to be experiencing pain

• We get cues on how to perceive pain from our culture’s views on pain.

Methods to control pain

• Drugs

• Surgery

• Acupuncture

• Massage

• Exercise

Taste (Gustation)

One of the two chemical senses

• On the top and sides of your tongue, there are 200 or more taste buds

• Each taste bud contains a pore that catches food chemicals