AP PSYCH - Unit 3

Psychophysics: 

Relationship between physical stimuli and sensations/perceptions they create

Necker Cube:

• Perception can be ambiguous

• Produces two perceptions 

  • Stimulus does not change but what we experience does

Sensory transduction:

• Receptors convert a physical energy/ image into nerve impulses

Words to know:

Exteroception: 5 senses

Introception: perception from inside of body

What we notice:

• Only 1% of the outside world is what we notice, the rest is filtered

Selection:

• Selecting where to direct our attention is the first step in perception

• Selective attention/ features detectors help explain why we pay attention to some stimuli and not others

Feature detectors:

• Brain has specialized neurons → responds to only certain stimuli

• Occipital lobes visual cortez

• Respond to special features of an image

  • Angles, lines, curves, movements 

Cocktail party effect:

• Auditory blindness

Change Blindness:

• Are we paying attention?

Exploring the senses: 

Subliminal: below what we could sense

Absolute threshold: smallest level of stimuli that can be detected at least 50% of the time

Absolute threshold:

vision: smallest level of light a person can detect

• How far a person can stand away from a candle and see the flame

oders: smallest level of a small a person can detect

• How little perfume in a large room

touch: the amount of force required to detect a feeling on your body

• Can vary depends on which part of the body (HOMUNCULUS)

Just Noticeable Difference:

Smallest change a person can detect 50% of the time

Weber's Law:

Ability to notice a change in stimulus in proportion to intensity of stimulus

LARGE JND: high intensity

SMALL JND: low intensity

• CONSTANT PROPORTION, NOT AMOUNT

Bottom up VS Top down processing:

Bottom up: relies on properties of the stimulus (patterns of light and dark areas)

Top down: relies on higher level info (prior knowledge and experience)

Sensory Adaptation Vs Habituation  

Habituation:  gradually over time and involuntarily.  

Sensory Adaptation: being exposed to the stimuli and getting used to it.  

Subliminal threshold:

Subliminal threshold: when energy of threshold is below one's absolute threshold for conscious awareness

Single detection theory: 

NO single absolute threshold (instead: intensity of stimulus, background noise, and motivation.)

Vision: 

Cornea: outer layer of eye

Iris: color

Lens: lies behind the eye and bends light

Retina: thin layer of cells in back of eye (FOCUSES LIGHT ON PARTICULAR POINT)

Cells:

Photoreceptor: detects light and color

Rods: black/ white

Cones: colors, bright light

Bipolar: passes signals

Ganglion: sends visual info from retina to brain

Visual transduction:

Transduction: stimulus becomes electrical signal processed by brain

Light:

Form of energy composed of photons (energy)

• Rods / cones are photon receptors

• Only bends when going through transparent materials

Color/ electromagnetic energy:

We DO NOT see color, we see electromagnetic energy

Physical characteristics:

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

Hue: dimension of color

Intensity: amount of energy in light/ sound wave (DETERMINED BY AMP)

Color does not exist: 

Color is made up of wavelengths of light that are visible to us

Visible light spectrum:

High = fast (RED)

Low = slow (PURPLE)

Two theories:

• Trichromatic theory: HELMHOLTZ AND YOUNG)

  • RBG

    • Retina ←> fovea

    • Color ←> 3 cones

  • Rods: most sensitive to light/ dark changes + movement found on the periphery of the retina

  • Cones: only in bright light, used for color vision + fine detail

• Opponent processing: (EWALD HERING)

  • Our color perception is controlled by color combos we do not see

    • Inhibitory / excitatory response

  • Occurs in ganglion cells and in the thalamus (LGN)

  • After images are activated and others are not

    • red/ green, blue/ yellow, black/ white

Color blindness: 

• Most commonly through genetics

• Found on the X chromosome

Symptoms:

• Differentiating how bright colors are

• Differentiating the shades of the colors

• Difference between the colors

How:

If a person lacks in a cone, they are color blind

Lateral inhibition: 

Capacity of excited neurons to reduce capacity of neighboring neurons

Sound:

3 qualities of sound waves:

Frequency: speed of wave (PITCH Hz)

• BELOW 20 Hz = infrasonic

• ABOVE 20 Hz = ultrasonic

Amplitude: height of wave (LOUD dBs)

• Level 0 = absolute threshold

• 120 dBs = destroys hearing

Timbre: tone color

• Quality of sound

• Made in comparison with another sound of the same frequency and amplitude

Audition: vibrating air molecules / pressure wave

Cochlea:

Where transduction takes place

• Hairs (stimulated with movement of membrane)

Frequency theory / Place theory / Other:

F Theory: Different part of the cochlea are better than others when hearing certain sounds (LOW PITCHED SOUNDS)

P Theory: how sound is received and perceived by the human ear (HIGH PITCHED SOUNDS)

Volley principle: groups of auditory neurons take turns firing (on and off)

Deafness:

Conduction: damage to middle ear (EAR WAX)

Sensorineural: damage to inner ear (HAIR CELLS DAMAGED)

Presbycusis: age genetic deafness (HAIR CELLS WEARING OUT)

Tinnitus: perception of prolonged noise when no noise is present (MANY WAYS CAUSED)

Highs and lows of audition:

Maximum amp: 150 dB

Minimum: 3-5 dB

Maximum freq: 20K Hz

Minimum: 25 Hz

Taste + Smell:

Papillae and taste buds:

Papillae: bumps on tongue

Taste buds: inside of papillae

Gustatory Hairs:

• Each cell has a long hair that extends from a small opening, or taste pore, and mingles with molecules of food introduced by saliva

• The saliva solution contains digestive enzymes that help break down foods chemically

Super tasters:

Long hairs or taste poor

Taste VS. Flavor:

Taste is the neurochemical process

Flavor is the sensory experience

Insular cortex:

Immediate sensation then response to taste

Factors that influence taste:

• Aging

• drugs/ alc

• Sinus problems

• Problems in temporal lobe

Process of smelling:

1. As a person takes a breath, the oder particles in the air flow to the top of the nose

2. Then a thin film of mucous containing olfactory receptors dissolves the oder particles. Then it sends a chemical message to the brain

3. After the brain tells the person what kind of smell it is (GOOD/BAD)

Pheromones:

Chemicals that are secreted in our sweat and other bodily fluids.

• believed to influence the behavior of the opposite sex, such as triggering sexual interest and excitement

Types of olfaction disorders:

Hyposmia: ability to detect odors is reduced 

Hyperosmia: heightened ability to detect odors

AnosmiaL inability to detect odors. 

Types of gustation disorders: 

Hypogeusia: reduced ability to taste flavors

Ageusia: cannot detect tastes

Dysgeusia: metallic/ nasty taste is persistent in a persons mouth

Causes disorders:

• Aging

• Sinus

• Smoking

• Head injury

• Dental problems

Somesthetic senses: 

Proprioception:

Kinesthesis: giving a person a sense of where they are in space (WITHOUT VISUAL HELP)

Vestibular sense: monitors balance and equilibrium

Vestibular system: IN EAR!

• Utricle detects linear motion in the horizontal plane (accelerating/decelerating in a car)

• Saccule detects linear motion in the vertical plane (movement in an elevator)

• It then communicates with the cerebellum

Sense of touch/ Pain:

• Skin is the largest organ

• 5 million mechanoreceptors (touch receptors)

  • Temperature

  • Pressure

  • Pain

Receptors:

There are different types of receptors inside of the skin

Nociceptors:

• A sensory receptors that respond to pain (temperature, pressure, cuts, chemicals, breaks, etc..)

• When activated, they transmit pain signals (via the peripheral nerves as well as the spinal cord) to the brain.

• Nociceptive pain is usually time limited, meaning when the tissue damage heals, the pain typically resolves. (Arthritis is an exception)

How does pain travel?:

• Travel along the PNS to the brain

• Gate control theory:  “gates” on the bundle of nerve fibers in the spinal cord between the peripheral nerves and the brain.

3 types of pain receptors:

• Cutaneous: SKIN

• Somatic: JOINTS / BONES

• Visceral: Body organs

Where is pain perceived:

Anterior Cingulate Cortex

• Located along the fissure that separates the frontal lobes

• Right above the corpus callosum

• Neural Alarm System that something is wrong

Gates in the Spinal Cord

The “nerve gates” in the spinal cord can open or close

1.  When the gates are opened, pain messages “get through” more easily and pain can be intense. A fibers

2.  C Fibers can close the gate, pain messages are prevented from reaching the brain and may not even be experienced.

•  rubbing the area around the injury/ acupuncture/STIM/Massage

3.  Endorphins and distractions can also cause this pain to be felt less (meditation, yoga, etc)

Periaqueductal Gray: 

This brainstem region releases pain blocking opiates and endorphins. Causes inhibitory neurons to nullify the pain messages.

Pain:

• Pain tells the body that something has gone wrong. 

• Usually pain results from damage to the skin and other tissues.

(Congenital Analgesia): CIPA

• CIPA is caused by a genetic mutation that prevents the formation of nerve cells responsible for transmitting signals of pain, heat, and cold in the brain.

• They do not sweat.

Pain Control: 

• Pain can be controlled by a number of therapies including, drugs, surgery, acupuncture, exercise, hypnosis, and even thought distraction.

Analgesics – Pain Killer: 

Types

1.  Anti inflammatory: NSAIDS/ ADVIL - non-steroids aspirins and ibuprofen - block all pain messages from the site of the pain - at the mechanoreceptor

2. Acetaminophen: Tylenol inhibits and or reduces pain and fever but not the inflammation: raises the pain threshold

3. Opioids: Narcotics - INCREASED OPIATES decreased perception of pain, decreased reaction to pain as well as increased pain tolerance (THRESHOLD)

4. Natural: Morphine, Codeine / Semi-Synthetic Heroin

5. Synthetic: Oxycodone, Percocet, Vicodin

Addiction to Pain Medication: 

• The brain increases the number of receptors for opiates and the brain’s production of endorphins decrease 

• The reduction of the brain’s endorphins causes a physical dependency on an external supply of opiates - ADDICTION

Types of Pain: 

1. Somatic: body

2. Referred pain: pain felt in an area not injured

3. Psychosomatic: the sensation of pain that can be influenced by emotions, past experiences and suggestions.

4. Phantom or illusory pain: the experience of pain without any signals from nociceptors

5. Acute Pain: short or limited duration

6. Chronic: long term

Headaches:

• Anatomy of a Headache. Although it may feel like it, a headache is not actually a pain in your brain.

• The brain tells you when other parts of your body hurt, but it can't feel pain itself. Most headaches happen in the nerves, blood vessels, and muscles that cover a person's head and neck.

CAUSES

• stress 

• dehydration 

• computer or TV watching

• loud music 

• etc

Tension headaches:

• STRESS FATIGUE 

• POOR POSTURE

• HOLDING YOUR HEAD AT A CERTAIN ANGLE

• HEAD OR NECK INJURY

Sinus headaches: 

• SINUSITIS, ALLERGIES AND COLDS

Cluster headaches: 

• Stabbing pain in eye

Causes of migraines:

• Drinks. Alcohol and caffeine

• Stress.

• Sensory stimuli.

• Changes in wake-sleep pattern

• etc

Biopsychosocial Influences:

Vestibular sense:

• Transduction begins in the semicircular canals in the inner ear.

• It is the fluid in the canals that stimulate the hair cells - cilia and send messages to the brain about speed and direction of body rotation.

• The semicircular canals give a sense of position 

• - Motion sickness is a result of excessive stimulation of the semicircular canals

Examples: 

• Moving your head

• Stand on one leg and stay balanced

• Spin yourself around and walk

• etc

  Perception:

  Interpreting information from our senses

  Factors that influence: 

  • Personal traits: characteristics (such as our interests, needs, and expectations) 

  • Past experiences

  • Context: The situation we're in can impact how we perceive others.

  • Culture: Culture, race, gender, sexual orientation, class, nationality, and age

  • Emotion and motivation

  • How we process information

  • Beliefs: beliefs, level of education, family histories, gender experience, health experiences, and nationality

  School of Gestalt: 

  • Nature driven perception (hard wired to see certain patterns in stimuli)

  • The whole ≠ sum of parts

  • Developed the laws of perceptual grouping 

   Principle of closure:

  • Tendency to perceive incomplete figures as complete by filling in the missing parts

  Principle of continuity: 

  • Points that are connected by lines that follow a path

  
  

  Principle of proximity:

  • Objects that are grouped together seem more related than elements that are far apart

  Principle of similarity:

  • Tendency to perceive objects that are similar as being together

  Law of simplicity:

  • Ignoring the redundant things

  • COMMON SENSE

  Law of pragnanz:

  • How people process visual information

  Factors that help us perceive: 

  • Feature Detectors - Visual Cortex

  • Bottom-up (stimulus driven) or Top Down processing (schema - mental model driven) 

  • Perceptual Constancies color, shape, size

  Figure ground:

  Allows a person to look at the figure directly without having to pay attention to the background

  Depth Perception: 

  Eyes ability to judge distance between two objects

  • Binocular Cues - both eyes

  • Monocular Cues - pictorial depth cues

  Pictorial depth cues: 

  • Light and Shadows: lighter colored objects look closer/ shadow on the top vs shadow on bottom

  • Overlap / Occlusion/ Interposition: blocking

  • Aerial / Atmospheric Perspective/ Relative clarity: hazier or foggier in the distance

  • Linear Perspective: Parallel lines appear to meet as they travel into the distance

  • Texture Gradient: when you look at an object in the distance such as a grassy field the texture becomes harder to see as opposed to close up 

  • Relative Height objects further away look taller in our field of vision

  • Relative Size: if objects are the same size the largest one will be judged as being closest to us

  Binocular cues:

  Clues to relative distance between different objects

  Retinal disparity:

  Difference between the two images

  Closer object = larger disparity

  Convergence: 

  Degree in which eyes face forward

  Closer the object = smaller disparity 

  Relative size:

  The more distance an object is, the smaller it seems

  Relative height:

  Objects that are higher seem further away than objects that are lower

  Interposition:

  Objects that block other objects seem closer

  Linear perspective:

  Parallel lines appear to converge in the distance. The more the lines converge, the greater their perceived distance

  Monocular cues:

  Light and shadow: 

  Nearby objects reflect more light into our eyes than more distant objects. Given two identical objects, the dimmer one appears to be farther away.

  Aerial Perspective (Relative Clarity):

  is the tendency of far away objects to appear more hazy or slightly blurred as a result of the atmosphere

  
  

  Texture gradient:

  Objects further away have less detail

  Accommodation:

  is not a pictorial cue but a muscular cue and helpful for objects close up

  Motion Parallax / Relative Motion:

  as you move objects at different distances appear to move at different rates -discrepancy of speed depends on the distance

  Apparent motion:

  refers to the perception of movement where there is actually none creating the illusion of continuous motion. (occurring when static images are presented in rapid succession)

  • It is key in understanding perception because it demonstrates how the brain actively interprets visual information, "filling in" gaps to create a coherent experience, and is fundamental to how we see motion in film and other visual media.

  Phi phenomenon: 

  • The illusion of movement created by presenting visual stimuli in rapid succession

  Strobic motion: 

  • The illusion of movement through rapid photos changing (animation)

  Ocular movement:

  • When our eyes quickly jump from one position to another (saccades.)

  Autokinetic effect/ image:

  The autokinetic effect (autokinesis) is a phenomenon of visual perception in which a small point of light in a dark environment appears to move

  Ponzo illusion:

  Parallel lines trick the brain into thinking the closer lines are farther away. They are the same size.

  Muller - Lyer illusion:

  Outward fins create an illusion of of greater length than inner fins 

  Relative motion:

  the motion of one object with respect to another object

  • Video in a car, the trees seem to be moving slower than ground

  Hermann Grid:

  Inattentional blindness:

  Failure to see objects  when our attention is directed elsewhere

  Change blindness:

  Failure to see objects changing slightly

  • Memory issue

  Stroop test:

  Perceptual set:

  A mental predisposition to perceive one object but not another