AP Psychology 1.6 - Sensation

Sensation

the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment; automatic

• sensory receptors

Sensory Receptors

sensory nerve endings that respond to stimuli

Perception

the process of organizing and interpreting sensory info, enabling us to recognize meaningful objects and events; not automatic

Bottom-Up Processing

starts with sensory receptors and works up to the brain

• also called feature analysis (we use the features of the object to build a complete perception

• piece by piece

Top-Down Processing

our brain interprets what our senses detect; use past experiences and expectations

• perceive by filling in the gaps of our senses

Transduction

converting energy from our senses into neural processes that our brain can interpret

Psychophysics

the study of relationships between the physical characteristics of stimuli (intensity) and our psychological experience of them

Absolute Threshold

the point in time when a stimulus goes from indetectable to detectable to our senses

• detectability must happen at least 50% of the time to be deemed the ___

• vary with age

Signal Detection Theory

a theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)

• assumes there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivations, and alertness

Difference Threshold

how much a stimulus needs to change before we notice the difference

• Just Noticeable: smallest amount of change needed in a stimulus before we detect change

• Weber’s Law

Weber’s Law

the changed needed is proportional to the original intensity of the stimulus

Subliminal Stimuli

stimuli that are below our absolute threshold

• research says sometimes subliminal messages can affect our behavior in subtle ways

• Priming

Priming

predisposing one’s perception, memory, or response

Dual Processing

processing occurs automatically; both consciously and unconsciously

Selective Attention

the focusing of conscious awareness on a particular stimuli

• Examples: cocktail party effect, accidents

Cocktail Party Effect

your ability to attend to only one voice among many; when you hear your name across the room you instantly bring that voice into consciousness

Accidental Selective Attention

your attention can shift back and forth but when a more demanding situation requires your attention you stop the other

Change Blindness

blindness to change in the environment

Inattentional Blindess

failing to see visible objects when our attention is directed elsewhere

Choice Blindness

you don’t notice the choices you made

Pop-Out Phenomenon

stimuli that are so powerful that they draw our eye and demand our attention without our choice

Principles of Sensation

• Subliminal Stimulation

• Sensory Adaptation

• Sensory Habituation

Subliminal Stimulation

sensory stimulation that is below a person’s threshold for perception; can’t be see by the naked eye or consciously heard

Sensory Adaptation

a phenomenon that occurs when the sensory receptors become exposed to stimuli for a prolonged period

Sensory Habituation

a pattern of decreased response to a stimulus after repeated exposure

Synethesia

senses overlap such as a word/sound having a taste, feeling, and/or visual effect

Vision

our eyes recieve stimuli and through the process of transduction we interpret the info

Wavelength

the distance from the peak of one light wave or sound wave to the peak of the next

Hue

the color we experience

Intensity

the amount of energy in a light wave or sound wave which influences what we perceive as brightness or loudness

Parts of the Eye

• cornea

• pupil

• iris

• retina

• lens

• ganglion cells

• optic nerve

• blindspot

• rods

• cones

Cornea

the eyes clear protective outer layer that covers the pupil and iris

Pupil

the adjustable opening on the center of the eye through which light enters the eye

Iris

the ring of muscle tissue that formed the colored portion of the eye around the pupil and controls the size of the pupil opening

Retina

the photosensitive surface of the back of the eye containing the receptor rods and cones plus neurons to help begin the process of interpreting the visual info

Lens

the transparent part behind the pupil that changes the shape to help focus images on the retina; this process is called accomodation

Accomodation

the process by which the eye’s lends changes shape to focus the images of near or far objects on the retina

Ganglion Cells

axons twin together to form the optic nerve

Optic Nerve

the nerve that carries nerual impulse from the eye to the brain

Blindspot

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

Rods

detect shape and movement

• on the periphery of the eye

• use for night vision because only a few bits of light can activate a rod

• play a role in light and dark adaptation

Cones

located in the fovea and process color and detail

• blue cones detect short waves

• green cones detect medium wavelengths

• red cones detect long wavelengths

Color Deficiencies

• Monochromat

• Dichromat

• Trichromat

Monochromat

black/white/gray (very rare)

Dichromat

red/green or yellow/blue

Trichromat

all colors

Trichromatic Theory

theory that the retina contains 3 different types of color receptors: red, green, and blue

• Critics: can’t explain afterimages; can’t explain color blindness

Opponent-Processing Theory

states that the sensory receptors arranged in the retina come in pairs (red/green, yellow/blue, black/white) and when one sensory is stimulated its pair is inhibited from firing

Parallel Processing

the brain is doing many things at one time

• analyzing color, depth movement, form, etc.

• damage to the brain can prevent ___ from happening

Afterimages

a result of certain ganglion cells in the retina that are activated while others are not

Visual Information Processing

scene → retinal processing → feature detection → parallel processing → recognition

Audtion

act of hearing

Pitch

a tone’s experienced in highness or lowness; different wavelengths

Amplitude

the heigh of the wave and determines the loudness of the sound (decibels)

Frequency

the length of the wavelengths that pass a point in a given time

Parts of the Ear

• middle ear

• inner ear

• cochlea

Middle Ear

the chamber between the eardrum and the cochlea containing 3 tiny bones that concentrate the vibration of the eardrum on the cochlea oval window

Inner Ear

the innermost part of the ear, contains the cochlea, semicircular canals and the vestibular sacs

Cochlea

a coiled, bony, fluid-filled tube in the inner ear; sounds traveling through the cochlear fluid trigger nerve impulses

Conduction Hearing Loss

sound waves cannot progress normally through the outer and/or middle ear

• the mechanism involved: outer ear, ear drum, and bones in middle ear

• possible causes: blockage, trauma to the eardrum, hearing loss can be selective

• something is wrong with the system of conducting the sound to the cochlea

Sensorineural Hearing Loss

impacts loudness, clarity, and range of sounds

• the mechanism involved: cochlear hair cells (celia) and auditory nerve

• causes: more common, aging, trauma, disease

• harder to treat because there is no method that can encourage the celia to regenerate

Place Theory

the celia in the cochlea respond to different frequencies of sound based on where they are located

• we sense pitch because the celia move in different placed in the cochlea

• Critics: does not explain lower tones

Frequency Theory

we sense pitch because of the celia fires (neural impulses) at different rates in the cochlea

• lower tones are sensed by the rate at which cells fire

• Critics: cannot explain how we can sense frequencies above 1000 waves per second

Volley Theory

the ear converts acoustic vibrations into nerve impulses or frequencies by causing groups of neurons to fire repeatedly and slightly out of phase with each other

• produces a stream of nerve impulses more rapid than firing individual neiros

• Critics: cannot account for all the sounds are able to hear

Sound Localization

describes how we identify where sounds in our environment are coming from

• involves the auditory system and auditory cues to determine the direction and distance of sounds

• usually the sound will be loudest in the ear that it reaches first

Olfaction

chemical sense; combinations of olfactory receptors activate different neuron pattern that allow us to distinguish different aromas and smells

• only sense not processed first in the thalamus

How Olfaction Works

• molecules of substance are in the air

• molecules settle in a mucous membrane and are absorbed by receptor cells

• receptor cells are linked to the olfactory bulb

• olfactory bulb sense messages to the brain

• the nerve fibers from the olfactory bulb connect to the brain at the amygdala and hippocampus which helps explain why smell is a memory trigger

Proust Phenomenon

the sudden, involuntary autobiographical memory, including a range of related sensory and emotional expression

Gustation

chemical sense; chemicals from food or other items we put in our mouth is absorbed by taste buds on our tongue

• oleogustus

• sweet

• salty

• sour

• bitter

• umami

Oleogustus

taste of fat, insulation, cell growth

Sweet

energy source; makes sure we take in enough carbohydrates

Salty

sodium essential to physiological process and regulate the amount of water in the body

Sour

alert to potential toxic substance

Bitter

alert to potential poisonous substance

Umami

alerts us to proteins that helps us grow and repair

Papillae

the bumps on your tongue that have the taste buds; the more densely packed the taste buds, the more chemicals are absorbed and the more intensely the food is tasted

Taste Receptors

detect the chemical component of food/drink; reproduce themselves (1-2 weeks)

• decrease with age

• alcohol or smoking can accelerate their decline

Sensory Interaction

the principle that one sense may influence another

• smells influences taste

• hearing and vision with close captioning

Touch

essential to our development; pressure, warmth, cold, pain; nerve endings are concentrated in different parts of our body

• pain is a useful response because it warns us of potential dangers

Homunculus

the system for sensing the position and movement of individual body parts; receptors in the muscle, tendons and joints that allow humans and other animals to control and coordinate their movements

Vestibular Sense

the sense of the body movement and position, including the sense of balance

Pain

the way the body tells us something is wrong; experiences depend on physiology, experiences and attention, surrounding culture

• combines bottom-up and top-down processing

Gate-Control Theory

Ronald Melzack, Patrick Wall’s; spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass

• the “gate” is opened by the activity of pain signals traveling up small nerve fibers and is close by activity in large nerve fibers and is closed by activity in large nerve fibers or info coming from the brain

Phantom Limb

the sensation than an amputated or missing limb is still attached to the body and is moving appropriately with other body parts

Pain Psychological Influences

• distraction can decrease pain

• our memories of pain are often different than what we actually experienced

  • people overlook pain duration

  • people don’t remember pain intensity

Pain Social-Cultural Influences

pain perception varies with our social situation and cultural traditions

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

• Biopsychosocial Approach: our experience of pain is from more than just neural messages

Congential Insensitivity to Touch

a condition that inhibits the ability to perceive physical pain