APPSYCH Sensation & Perception

Detecting physical energy/stimulus from the environment via sensory neurons

Same for everyone

How one interprets, organizes, make sense of world

Personal and unique

Conversion of external stimulus into neural impulse for brain to interpret

Senses --> Brain (sensory neurons to brain)

Happens in real time, reliant on sensory experience

Brain --> Perception

Prior knowledge and information

Smallest amount of stimuli that can be reliably detected (50%)

Occurs with constant, unchanging stimuli Sensory neurons fire less frequently as the brain gets used to stimuli

Because of Sensory Adaption Brain pays less attention to stimuli, doesn't need RAS

Explains why 50% detection is good Accounts for psychological state for attuning of sense -Motivation -Emotional State -How many other things are being concentrated on

Smallest amount of change in ongoing stimuli that can be reliably detected (50%)

Brain focuses on particular thing and will ignore other distractions

Failing to notice change in environment

Failing to see visible objects when attention directed elsewhere

Example of Selective Attention Certain pieces of information (relevant to self) snap to brain's attention

JND proportional to the intensity of original stimuli Intense stimuli- more change to notice difference Weak stimuli- less change to notice difference

Below Absolute Threshold

Electromagnetic wave energy

Determines color/hue Long- Red Short- Violet

Determines brightness/intensity High- high brightness Low- low brightness

Determines saturation

Pressure waves from vibrations

Rate of vibrations per second Short- high pitch, more hertz, frequency Long- low pitch, less hertz, frequency Measured in hertz (Hz)

Determines intensity of pressure (loud) Low- quiet High- loud Measured in decibels (db)

Determines timbre/saturation/quality

Cornea -> Pupil -> Retina -> Optic Nerve

Outer curved membrane

1. Protects eye itself from dust

2. Focuses light waves into retina

Sphincter muscle that opens up eye, dilates/constricts pupil

Round milky disc in center of eye

1. Flips image upside down (curvature)

2. Focuses image with accommodation (changes thickness and shape)

Back layer of tissue covered in photoreceptors (specialized vision neurons- cones and rods)

Responsible for color vision

Responsible for grayscale vision More Rods than Cones Reacts to Wave Amplitude

Central point of focus/clearest image Most densely packed cones

Photoreceptors -> Bipolar Cell -> Ganglion Cell Axons create Optic Nerve

Blind Spot: where Optic Nerve leaves eye

Broken down into smaller pieces and worked on at same time

Transduction on retina Vision: color, depth perception, form, motion

Occipital lobe and visual cortex

Hubel/Wisel- Theory of specialized cells in occipital lobe for visual parallel processing

Only for Colors in Light Happens in eye

Cones in eyes are sensitive to red/green/blue (RGB) light

Edward Hering

Parasympathetic process in brain

Red/Green, Blue/Yellow, Black/White

Cochlear

Semicircular Canals

Oval Window

Sensing organ for sound in Inner Ear

Contains cilia for vibrations

Structure in Inner Ear meant for balance

*No effect on hearing

Pinna

Auditory Ear Canal

Visible Ear Structure (Outer Ear)

Funnels sound into the ear

Human, fixed: harder to locate sound

Outer Ear (canal with earwax)

Bounces off sound waves to continue vibrations into ear

Eardrum/Tympanic Membrane

Ossicles (Malleus/Hammer, Incus/Anvil, Stapes/Stirrup)

Gateway of Outer Ear to Middle Ear (Middle Ear)

Thin layer of tissue that conducts vibrations

Middle Ear

Malleus/Hammer, Incus/Anvil, Stapes/Stirrup

Hammer (Ossicle-Middle Ear)

Anvil (Ossicle-Middle Ear)

Stirrup (Ossicle-Middle Ear)

Pinna —> Auditory Ear Canal —> Eardrum —> Ossicles —> Auditory Nerve

Gateway to Inner Ear (Inner Ear)

Pushes on fluid in inner ear for cilia to bend, sends neural impulse

Middle Ear Problem

1. Perforated Eardrum (too much pressure stretches/tears eardrum)

2. Genetic disorder of Ossicles (calcify/wear away, no moving hari cells)

Middle Ear cannot conduct vibrations

1. Death of Hair Cells in Ear

1st to die are higher frequency cells in front of cochlea

• Hearing Aids amplify vibrations to stimulate alive hair cells

Auditory Nerve not receiving messages for sound

Herman von Helmholtz

Links audible pitch to place where cochlea’s membrane is stimulated

Based on how hair cells are moving

Explains high/middle frequencies; not low frequencies (whole membrane moves)

Rate of nerve impulses traveling up auditory nerve matches tone frequency —> we can sense pitch

Based on how fast/slow messages go in ear

• High frequencies: faster message, high vibration

• Low frequencies: slower message, less vibration

Able to hear higher than 1000hz, does not account for neuron refractory period

Sense of Balance/Equilibrium

Controlled by Inner Ear’s Semicircular Canals (fluid moves into hair cells that line membrane, bending of hair cells sends brain messages relative to ground)

Information about body part movement and orientation

Sense receptors in muscles, joints, tendons sends messages to brain

Skin of Receptors for Olfaction

Stimuli are chemical molecules

Gustation (Taste), Olfaction (Smell)

Combination of Sensations (Pressure, Pain, Warm, Cold)

Processed in parietal lobe, somatosensory cortex

Pain from internal organs, constant ache

Pain from muscles/tendons, sharp and quick pains

Theoretic pain gate in spinal cord (Opens for pain messages to go to brain, closes with large fiber activity)

Pain signals conducted by small spinal cord nerve fibers

Amputation damages nerve fibers for closed gate

Brain misinterprets/amplifies spontaneous and irrelevant activity from Central Nervous System

Phantom sights, smells, taste: nerve damage

Brain’s tendency to integrate information into meaning wholes

“Organized whole that is perceived as more than the sum of its part”

• Different from Structuralism (focus on parts of mental experience)

• Different from Functionalism (focus on introspection of mind’s adaptive functions)

Object distinct to surroundings

Ex. (black vase in white bg vs white vase in black bg)

• Needed to perceive the environment

Proximity, Similarity, Common Fate, Closure, Pragnanz, Continuity, Figure-Ground

Gestalt Principle

Individual perceives several close objects as belonging together

Gestalt Principle

Individual perceives like items as belonging together

Gestalt Principle

Individuals see objects as continuous instead of disjointed

Gestalt Principle

Brain will interpret things easily and organize objects simply

Gestalt Principle

Individuals fill in the blanks of missing portions of picture

Gestalt Principle

Elements are grouped because they move at same speed/in same direction

Perception/Illusion of movement

Stationary lights turned on/off in succession to give illusion of movement (stroboscopic movement)

Illusion of pictures through motion

Fixed objects move with moving viewer

• Beyond point: move with viewer, faster

• Closer to point: move backwards

Single-eyed illusions of depth

Linear perspective, Interposition/Occlusion, Relative size, Relative height, Relative clarity, Light and shadow, Texture Gradient, Motion parallax

Monocular Cue

Parallel lines converge at vanishing point on horizon

Monocular Cue

Partial blocking of one object by another object

Monocular Cue

Object perceived as smaller = farther away than like object in foreground

Monocular Cue

Objects higher in field of vision are farther away

Monocular Cue

Objects that are clearer appear closer than blurry objects

Monocular Cue

Objects that are closer reflect more light, farther objects are dimmer

Monocular Cue

Visual degree of detail: Closer objects have clearer gradient, Farther objects are smoother and less detailed

Monocular Cue

Closer objects move faster than farther ones

Double-eyed illusions of depth

Retinal disparity, Convergence

Binocular Cue

Eye perception of image are different because of different angles

Used to perceive distance based on the different image in the two retinas

Binocular Cue

How far inwards eyes need to move to focus on object

More convergence, closer object is to middle of face

Ability to see the world in 3D

Study by Eleanor Gibson and Richard Walk

Depth perception is not innate- babies are born nearsighted

Object remains the same, even when it looks different

Object remains the same shape, even when there is a change in point of view

Object stays in same place, even if viewer moves around

Object stays same color, even if light wavelength reaching viewer changes

Object is the same brightness, even when it reflects different amounts of light through lighting

Object stays the same size, even when image on retina gets bigger/smaller