Chapter 6: Sensation and Perception

How do we detect loudness?

the number of activated hair cells -if a hair cell loses sensitivity to soft sounds, it may still react to loud sounds

figure-ground

the organization of visual field into objects (the figures) that stand out from background/surroundings (ground) ex. recognizing a voice from a crowd of noise

sublimal

stimuli you cannot detect 50 percent of the time; below absolute threshold

interoception

stimulus from inside body -sensory reception on internal organs

gestalt

"form" or "whole" -when given a cluster of sensations, people organize them into a whole, integrating pieces of information into meaningful wholes -filter information and construct perceptions -in-life: logos (Mac, twitter ex, panda)

What theories help us understand pitch perception?

-Hermann von Helmholtz's place theory -Frequency theory -volley principle

Describe the process that transforms vibrating air into nerve impulses, which the brain decodes as sounds

-Sound waves enter outer air, which channels waves to the eardrum, causing it to vibrate -in the middle ear, a piston made of 3 bones (hammer, anvil, and stirrup), transmits the vibrations to the cochlea, a tube in the inner air -the incoming vibrations cause the cochlea's membrane to vibrate, jostling the fluid that fills the tube, bending the hair cells lining the basilar membrane -movement triggers impulses in adjacent nerve cells, which converge to form the auditory nerve, which sends neural messages to the auditory cortex

Describe sound waves

-amplitude: determines loudness -frequency (length): determines pitch (long waves have low frequency, low pitch, short waves have high frequency, high pitch)

anchoring

-base impressions of objects on surroundings -asked people to guess certain factoids -asked participants to high or low anchor condition, asked to provide own guess: what anchor was influenced responses--perceptions of world depend on context we're given -ex: sales discounts, Starbucks sizes

cones

-cluster in and around the fovea (center of eye) -each one transmits to a single bipolar cell that helps relay individual message to the visual cortex -precise information, fine detail -daylight/well-lit -color -low sensitivity in light

Why is somatosensation important?

-communication -decreases stress (oxytocin) -improves health via mindfulness movement

What are some factors that influence perception?

-context (differently sized monsters) -emotion (sad, heavy music vs bouncy, light music) -motivation (water bottle seems closer to those who are thirsty)

How does light reach the retina?

-enters through cornea -passes through pupil -lens focuses light rays into image on light rays

schizophrenia

-high heritability (dopamine overproduction, synapse pruning), environmental triggers -positive (do not normally experience): delusions, sensory hallucinations -negative (absence of normal experience): anhedonia, absence of speech

How are smells processed?

-odor molecules (odorants) bind to receptors -olfactory receptor cells are activated and send electronic signals -the signals are relayed via converges axons -signals are transmitted to higher regions of the brain

the four shared principles of sensation

-physics (physical properties of stimulus) -physiology (body's sensory processing) -phenemenology (person's broader experience) -psychology (perceptions shape ABCs)

miscellaneous

-physiology impacts perception

parallel processing

-processing of many aspects of a problem simultaneously (ex. color, motion, form, depth), processes many functions, integrates separate but parallel work

cornea

-protects eye -bends light to provide focus -how light enters eye

What three steps are basic to all our sensory systems?

-receive sensory stimulation using specialized receptor cells -transform that stimulation into neural impulses -deliver the neural information to your brain

What is the pathway for somatosensation?

-receptors in skin -nerves -primary somatosensory cortex in brain -posterior parietal cortex, where secondary processing takes place -coordinates response -takes info from all senses, processes, sends to motor cortex

monocular depth cues

-relative height: objects higher in our field of vision are farther away -relative motion -relative size -interposition -linear perspective -light and shadow

rods

-share bipolar cells, sending combined messages -detect black, white, gray -peripheral -twilight vision (help see in dark) -highly sensitive to light

iris

-surrounds pupil -controls pupil size -dilates/constricts in response to light intensity and inner emotions

What two physical characteristics of light help determine our sensory experience of them?

-wavelength -intensity

How does light information pass through the retina?

1) light enters eye, triggering reaction in rods and cones in the back of the retina 2) chemical reaction in turn activates bipolar cells 3) bipolar cells activate ganglion cells, the axons of which converge to form the optic nerve. This nerve transmits information to the visual cortex in the brain via the thalamus

Summarize visual information processing

1) retinal processing: receptor rods and cones --> bipolar cells --> ganglion cells 2) feature detection: brain's detector cells respond to specific features (edges, lines, angles) 3) parallel processing: brain cell teams process combined information about color, movement, form, depth 4) recognition: brain interprets constructed image based on information from stored images

How does our system of sensing differ from vision, touch, and taste?

2 types of retinal receptors, 4 basic touch senses, 5 taste sensations, but no basic smell receptors. Instead, different combinations of odor receptors send messages to the brain, enabling us to recognize some 10,000 different smells

Molyneux's problem

Can a cube and sphere be visually distinguished based only on tactile experience? (No) Method: blindness can be corrected; subjects could not distinguish

What are the basic steps in transforming sound waves into perceived sound?

Outer ear collects sound waves, which are translated into mechanical waves by the middle ear and turned into fluid waves in the inner ear. The auditory nerve then translates the energy into electrical waves and sends them to the brain, which receives and interprets the sound.

controlling pain

Pain is a result of biological, psychological, and social-cultural influences. Pain can be addressed with placebos or distractions

Why is taste evolutionary advantageous?

Small children typically resist bitter/sour food because these were potentially dangerous sources of food poisoning. -taste buds regrow every 1-2 weeks, but as you grow older, the number of taste buds/taste sensitivity decreases

What are the two theories of color vision and how do they complement one another?

The Young-Helmholtz trichromatic theory and Hering's opponent process theory outline the stages of color vision: 1) the retina's receptors for red, green, and blue respond to different color stimuli 2) the receptors' signals are then processed by opponent-process cells on their way to the visual cortex in the brain

exteroception

any stimulus from outside

What does research suggest about the effects of experience on perception?

There is a critical period for normal sensory and perceptual development. Although adults are able to distinguish color and brightness (their senses have not degenerated), the cortical cells had not developed normal connections, causing them to be functionally blind to shape. Experience guides the brain's neural organization as it forms the pathways that affect perception.

How do we locate sounds?

Two ears, detects intensity and direction of sound

retinal disparity

a binocular cue for perceiving depth: by comparing images from the retinas in the two eyes (about 2.5 inches apart), the brain computes distance--the greater the disparity between the two images, the closer the object

retina

a multilayered tissue on the eyeball's sensitive inner surface -image appears upside-down and reversed -receptor cells convert light energy into neural impulses, forward those to brain

sensory experience

a prior: beliefs and experiences can influence our perception; role of existing beliefs ex. (Loch ness, UFOs) ex. things that are farther back are smaller: monster picture ex. culture window/box

perceptual set

a set of mental tendencies and assumptions that greatly affects what we perceive -top-down -ex: saxophone man / woman's face picture

pupil

a small adjustable opening in eye

perceptual adaptation

ability to adjust to an artificially displaced or even inverted visual field; humans are able to adapt quickly

depth perception

ability to see objects in three dimensions although the images that strike the retina are two-dimensional -allows us to judge distance

bottom-up processing

analysis that begins with the sensory receptors and works up to the brain's integration of sensory information

How do we normally perceive depth?

binocular and monocular cues

How does wave amplitude affect our perception of colors?

bright colors have great amplitude while dull colors have small amplitude

transduction

process of converting one form of energy into another that your brain can use -how sensory inputs are translated into neural outputs

top-down processing

constructs perceptions from the sensory input by drawing on our experience and expectations

binocular cues

depth cues, such as retinal disparity, that depend on the use of two eyes

olfactory bulb

direct route to amygdala and hippocampus

lens

focuses incoming light rays into an imagine on the retina

sensory context

immediate surrounding environment influences our perception

proprioception

kinetic sense -helps monitor position of body relative to self/in space

Hermann von Helmholtz's place theory (high place)

links the pitch we hear with the place where the cochlea's membrane is stimulated

What kind of wavelengths do red colors have?

long wavelength, low frequency

vestibular sense (body movement)

monitors head's/body's position and movement -movement of fluids in inner ear

sensorineural hearing loss

nerve deafness -damage to cochlea's receptor cells/auditory nerves

grouping

our minds bring order and form by organizing stimuli into groups: 1) proximity (group nearby figures together) 2) continuity (smooth, continuous patterns) 3) closure (fill in gaps to create a complete object

color constancy

perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object -experience of color depends on object's context

perceptual constancy

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

phenomology

perceptions shape ABCs: our perceptions of sensations are not fixed or static, but shaped by sensory experiences, sensory context, sensory experience -Gustave Fechner -humans behave according to naturalistic principles -perceptions are subjective; material world does not exist

volley principle

place theory best explains how we sense high pitches, frequency theory explains how we sense low pitches -combination handles pitches in intermedite range

perception

process by which the brain organizes and interprets sensory input -top-down

accomodation

process in which lens focuses incoming light rays by changing curvature to focus near or far objects on the retina

fovea

retina's area of central focus

kinesthesis (body position)

sense of position and movement of body parts

somatosensation

sense of touch 1) exteroception 2) interoception 3) proprioception

sensation

senses detect information and transmit that info to brain -bottom-up

nociceptors

sensory receptors that detect hurtful temperatures, chemicals, or pressure -respond to stimuli by sending an impulse to spinal cord, which passes the message to the brain, which interprets the signal as pain

What kind of wavelengths do blue colors have?

short wavelength, high frequency

feature detectors

specialized neurons in the occipital lobe's visual cortex that receive information from individual ganglion cells in the retina -nerve cells that respond to specific features of the stimulus, such as shape, angle, movement -responds to a scene's specific features--pass information to other cortical areas, where teams of cells respond to more complex patterns ex. helps recognize faces

priming

the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response

intensity

the amount of energy in light waves (determined by amplitude--height), which influences brightness

Why can odors invoke memories and feelings?

the brain's circuitry for smell connects with taste and areas involved in memory storage -smell is primitive

hue

the color we experience (blue, green, red, etc)

ESP (extrasensory perception)

the controversial claim that perception can occur apart from sensory input

wavelength

the distance from one wave peak to the next

embodied recognition

the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments

difference threshold (just noticeable difference, jnd)

the minimum difference a person can detect between any two stimuli half the time

absolute threshold

the minimum stimulation needed to detect a particular stimulus 50 percent of the time

blind spot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there -blind spot is on nose side of retina

sensory interaction

the principle that one sense may influence another -smell of food influences its taste -seeing captions to hear words -brain blends inputs from sensory channels

Weber's law

the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount) ex: two objects must differ in weight by 2 percent -lower levels, easier to notice changes (completely dark; flicker of light is noticeable)

frequency theory (low frequency--wq)

the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch

Young-Helmholtz trichromatic (three-color) theory

the retina has 3 types of color receptors, each especially receptive to red, green, and blue -combinations of these cones through stimuli allows us to see other colors -color-deficient vision lacks red/green sensitive cones

parapsychology

the study of paranormal phenomena, including ESP and psychokinesis

signal detection teory

theory predicting how/when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) -there is no absolute threshold and detection depends partly on a person's experience, expectations, motivation, and alertness

gate-control theory

theory that says 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 brain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain

Hering's opponent-process theory

three sets of opponent retinal processes (red-green, yellow-blue, white-black) enable color vision -for example, some cells are stimulated by red and inhibited by green

equilibrioception

vestibular sense: sense of body's position relative to external world (balance, based on fluid in inner ears)

sensory adaptation

when we are constantly exposed to a stimulus that does not change, we become less aware of it because nerve cells fire less frequently -reduces sensitivity, but -allows focus on informative changes without being distracted by background chatter