Unit Three: Sensations

Sensation

Process where sensory receptors and the nervous system receive stimulus energies from our environment

Perception

Organizing and interpreting sensory information enabling us to recognize meaningful objects and events

Five Senses

Hearing, smell, touch, taste, sight

Bottom-Up Processing

Analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information - everyone can do this

Top-Down Processing

Processing guided by higher-level mental processes, drawing on past experiences - not everyone can do this in every scenario - ex. looking at citation to learn author, date, etc.

Selective Attention

Focusing conscious awareness on a particular stimulus - we sense 11,000,000 bits of information per second and we can only process 40 - the brain prioritizes things that help us survive or give us rewards

Inattentional Blindness

Failing to see visible objects when our attention is directed elsewhere

Change Blindness

Failing to notice changes in your environment

Absolute Threshold

The minimum amount of stimulus needed to be detected 50% of the time

Signal Detection Theory

How and when we detect a faint stimulus within background stimulation

Subliminal

Below one’s absolute threshold for conscious awareness

Sensory Adaptation

Constant stimulation leading to diminished sensitivity (ex. our body odor, the taste of our water)

Parts of the Eye

• Pupil

• Iris

• Lens

• Retina

Pupil

Adjustable opening where light enters

Iris

Ring of muscle forming the colored portion of the eye, controls size of pupil opening

Lens

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

Retina

Light-sensitive inner surface of the eye, containing the receptor rods and cones, along with neurons that begin processing visual information

Parts of Retina

• Rods

• Cones

• Optic Nerve

• Fovea

Accomodation

Process where the eye’s lenses change shape to focus near or far objects on the retina

Rods

Receptors that detect black, white, and gray - peripheral vision and twilight vision

Cones

Receptor cells that are concentrated near the center of the retina and function in well-lit conditions - detect fine detail and color

Optic Nerve

Carries neural impulse from the eye to the brain - area where it leaves the eye is a blind spot

Fovea

Central focal point in the retina where cones cluster

Feature Detection

Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement

Parallel Processing

Processing many aspects of a problem simultaneously - found alongside other senses as well

Automatic Perception Types

• Closure (filling in the dots)

• Figure Ground Perception (what’s there and what’s not there)

• Proximity (grouping things together)

• Similarity (can’t find differences, ignore things that aren’t exact models)

• Continuity (smooth patterns)

• Common Fate (connecting people and their behavior

Stroboscopic Motion

Rapid progression makes still items seem as if they’re moving (flip book, video) - in general, we perceive motion in relation to the objects around it

Depth Perception

Our ability to interpret distance - monocular and binocular cues

Monocular Cues

Certain objects appearing closer in artwork, needing only one eye to be seen

Binocular Cues

Both eyes are required to determine distance - retinal disparity and convergence

Retinal Disparity

Difference between two images of an object that the retina receives as the object moves closer

Convergence

Maintaining a single image of an approaching object until our eyes converge

Perceptual Constancies

• Size Constancy

• Color Constancy

• Shape Constancy

• Brightness Constancy

Size Constancy

Ability to determine that objects far out aren’t actually small

Color Constancy

Tendency to perceive objects as keeping their color even though in different lighting it is difficult to determine

Shape Constancy

The knowledge that an item has only one shape no matter what angle you view it

Brightness Constancy

Lighting around an object doesn’t change its brightness

Young-Hemholtz Trichromatic Theory

Retina contains three different color receptors (red, green, blue) - when stimulated in any combination they create the perception of color - dichromatic people would only have two of the above receptors

Opponent-Process Theory

Opposing retinal processes enable color vision - red-green, yellow-blue, white-black, etc.

Middle Ear

Chamber between the eardrum and the cochlea containing three tiny bones (hammer, anvil, stirrup) - concentrate vibrations of the eardrum on the cochlea’s oval window

Inner Ear

Innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

Cochlea

Coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

Stimulus

Ears take in sound waves, turns them into nerve impulses, and our brain decodes it bigger amplitude means louder and vice versa - frequency and pitch

Frequency

Number of complete wavelengths that pass a point in a given time

Pitch

A tone’s experienced highness or lowness - higher frequency means a higher pitch and vice versa

Place Theory

Links the pitch we hear with the place where the cochlea’s membrane was stimulated

Frequency Theory

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

Doppler Effect

Change in frequency as the sound approaches or leaves - two ears help us find direction of sound

Conduction Hearing Loss

Caused by damage to the mechanical system that sends sound waves to the cochlea

Sensorineural Hearing Loss

Hearing loss caused by damage to the cochlea’s receptor cells or the auditory nerves

Cochlear Implant

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

Kinesthesis

The system for sensing the position and movement of individual body parts

Vestibular Sense

Sense of body movement and position, including the sense of balance - disrupted during puberty

Pain

Something has gone wrong, change your behavior - inability to feel pain is an evolutionary disadvantage - pain can be disrupted by the release of endorphins - pain is typically stored in memory at its worst point and how it felt at the end (duration is harder to remember) - we tend to feel more pan when others are also in pain (viewing pain)

Gate-Control Theory

The spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass onto the brain

Phantom Limb

Amputees feel pain or movement from body parts that no longer exist (7/10 amputees) - caused by misinterpreted CNS activity - deaf people can sometimes hear phantom rings

Taste

Chemical sense - sweet, sour, salty, bitter, umami - taste is pleasurable so that we seek out some foods and avoid others - 200 taste buds, each with 50-100 receptors each - receptors grow back about once a week

Smell

Chemical sense - over 5 million receptor cells in each nasal cavity - smell bypasses the Thalamus bc its so primitive - ability to identify smells peaks during early childhood - women typically have a better sense of smell (helps survival and reproduction)

Sensory Interaction

Senses work together to make each other stronger - ex. smell + texture = taste, or the inability to see something when there are loud noises present

Consciousness

Our awareness of ourselves and our environment

Unconscious

Unawareness of ourselves and our environment

Altered States

Consciousness disrupted by drugs, meditation, or trauma

Circadian Rhythym

Biological clock - regular bodily rhythms that occur on a 24-hour cycle (ex. sleep)

Ultradian Rhythym

Biological clock - regular bodily rhythms that occur more than once each day (ex. appetite)

Infradian Rhythm

Biological clock - regular bodily rhythms that occur once per month (ex. menstrual cycle)

Stages of Sleep

• Alpha Waves: slow brain waves of a relaxed, awake state

• Delta Waves: large, slow brain waves associated with deep sleep

• REM: recurring sleep stage where vivid dreams take place every 1.5 hours

  • Rapid Eye Movement

• NREM: encompasses all sleep stages besides REM

  • non-Rapid Eye Movement

How Much Sleep Do We Need?

Depends on the person (newborns 2/3 of day vs. adults 6 hours) - sleep recharges the brain and keeps it from overworking - sleep deprivation can lead to severe mental health issues