Psy201 Chapter 4

Front 1

Sensation

Back 1

Process by which sense organs gather information about the environment. Indication that something is there
Something is triggering a dendrite of a neuron

Front 2

Perception

Back 2

Process by which the brain selects, organizes and interprets sensations What is it that I am hearing/seeing/smelling?

Front 3

Top-down processing

Back 3

Perception begins at higher processing based on past experiences as soon as sensations occur (Deductive) Big picture first, then look at the small details. Basically stereotyping changing perception.

Front 4

Bottom-up processing

Back 4

Multiple sensations integrated into data in higher regions of the brain (inductive) Smaller parts from the environment are eventually turned into the big picture of the env.

Front 5

Three key principles of Sensation and Perception

Back 5

1) There is no one on one correspondence between physical and psychological reality
Your perception of reality and actual reality are usually similar but NOT the same
2) Sensation and Perception are active processes
We focus on stimuli that are relevant to us
3) Sensation and Perception are adaptable
We adapt to key stimuli in our environment (absolute/difference thresholds change)

Front 6

Features shared by all sensory systems

Back 6

- Must translate physical stimuli into sensory signal (so the brain can understand)
- Physical stimuli must surpass the minimum threshold
- Sensation requires constant decision making to identify meaningful stimuli, even at an unconcious level. We focus on loud, unique or personal signals like a gunshot or our name being called
- Efficient processing tunes out the repetitive signals. Eg. A clock ticking, a consistent smell.

Front 7

Transduction process

Back 7

is turning a sensory signal into something the brain can understand (chemical/electrical signal)

Front 8

Sensory Receptors

Back 8

Specialized cells that transfer the energy (stimuli) into neutral impulses to be detected by the brain (transduction)

Front 9

Absolute Threshold

Back 9

Minimum amount of physical energy needed for someone to notice the stimulus The level at which it is able to be detected 50% of the time
Varies from person to person with expectations, motivation and stress (eg. If you have a cold, need glasses)

Front 10

Difference Threshold

Back 10

The jnd (just-noticeable difference) is the lowest level of stimulation required In order to sense a change in the stimulation has occurred
The level of the original signal is key to detecting jnd. Eg. A small candle burning in a dark room is noticeable, it's not noticeable in direct sunlight, you'd need a huge candle to have a difference.

Front 11

Weber's Law

Back 11

For stimuli to be perceived as differing in intensity, the second must differ from the first by a constant proportion. The ratio of change in intensity in jnd is Weber's Fraction (the percentage of increase)

Front 12

Sensory Adaptation

Back 12

The tendency of your sensory systems to respond less to stimuli that continue without change.
eg. Adjusting to darkness in a theatre, high sound levels at a concert.
This prevents sensory overload.

Front 13

Vision + lens

Back 13

Light travels in wavelengths with higher/lower frequencies
Lens: Focus' image through accomodation (change in shape of lens that focus on light rays)

Front 14

Vision - Retina + Photoreceptors

Back 14

Lens: Focus' image through accomodation (change in shape of lens that focus on light rays)
Retina: Transduces light into electrical signals
Cones: Colour and fine detail
Rods: Black, white and grey

Front 15

Audition

Back 15

involves the vibrations in the air from the source (sound waves)
Travels slower than light but can travel through objects

Front 16

Audition -changes

Back 16

Frequency: Number of times waves cycle/second
Pitch: Psychological Property corresponding to freq.
Amplitude: (loudness) height and depth of the waves (psych property corresponding to pitch)
Timbre: Intensity or complexity of the sound

Front 17

Audition - The Ear

Back 17

Cochlea: Involved in hearing, tube in inner ear where sound is transduced
Basilar Membrane: Separates cochlear chambers
Hair Cells: attached to basilar membrane. Movement results in action potentials in sensory neurons

Front 18

Olfaction - sensing

Back 18

Enables us to detect danger or pleasant/good odors
- Spoilt food
- Mother's perfume
Many species communicate through pheromones
- Chemicals (hormones or scents) that allow communication

Front 19

Olfaction - physical

Back 19

Stimuli are molecules of gas entering through nose/mouth
Olfactory Nerve: Composed of axons from hundreds of different olfactory receptors
Olfactory Bulb: Receives signals from the Olfactory Nerve and transmits to Olfactory Cortex in the frontal lobe

Front 20

Taste - taste buds + papillae

Back 20

Sensitive to molecules in saliva.
10k tastebuds lining the papillae (bumps) of the tongue.
- contain taste receptors to transduce chemical input

Front 21

Taste - limbic system, primary gustatory cortex, four tastes

Back 21

Limbic System: generates unconscious reactions and learned reactions to taste
PGS: Identification of tastes
- Four tastes of PGS are Sweet, Sour, Salty, Bitter.

Front 22

Skin Senses

Back 22

18sq ft of skin. Used to protect from injury, identify objects, help maintain body temp, aid in social interactions (shaking hands)
Three senses: Pressure, Temp, Pain

Front 23

Skin - Pressure, Temperature and Pain

Back 23

Pressure: displacement of skin, very sensitive on hands and fingers, little sensitivity on butt.
Temperature: Difference between skin temp and object's temp
Pain: Purpose is to limit tissue damage, impacted by beliefs, emotional state and can be controlled by changing attitude about it

Front 24

Proprioceptive Senses

Back 24

Vestibular and Kinesthesia
Regulate body position and movement

Front 25

Vestibular

Back 25

Provides information on the position of the body by sensing gravity and movement.
The receptors are in the inner ear.

Front 26

Kinesthesia

Back 26

Provides information about the movement and position of the limbs and other body parts relative to one another

Front 27

Form Perception

Back 27

Organizing sensations into meaningful shapes and patterns.

Front 28

Gestalt Principles

Back 28

Key is that the WHOLE is greater than the parts.
Figure: The object being viewed
Ground: The background the object is embedded in

Front 29

Collections of Gestalt Principles

Back 29

Similarity: group similar elements together
Proximity: group objects that are close together, together
Good Continuation: Organising stimuli into continuous lines/patterns
Simplicity: We see the most simple pattern we can
Closure: We often see incomplete figures as being complete

Front 30

Depth Perception

Back 30

The organisation of perception in three dimensions!

Front 31

Binocular Clues

Back 31

Visual input from two eyes
Retinal Disaprity: slightly different view from each eye, greater difference fro close images.
Convergence: the physical turning of the eyes inwards to see close objects and eyes diverging when it's far

Front 32

Monocular Clues

Back 32

Interposition: When an object is blocked by another it's far away
Linear Perspective: Parallel lines converge in the distance /\
Texture Gradient: Closer it is the more texture you can see
Elevation: Far objects are higher up in comparison to the horizon
Familiar size: We assume objects are the usual size even if it appears small in the distance
Movement: Far away things are slow, close things are fast

Front 33

Two visual systems for processing movement

Back 33

Motion of the object being observed (ball moving towards a hand)
Motion of the person doing the observing (catcher moving to obtain the ball)

Front 34

Perceptual Consistancy

Back 34

Colour: We perceive common objects as the same colour regardless of illumination (apple=red)
Shape: Perceived as being the same shape regardless of the angle it's currently at. (door=rectangle)
Size: Objects remain the same size regardless of distance

Front 35

Perceptual Set

Back 35

Perceptual Set: The expectations or setting for perceptual interpretation (top down)
Context influences how sensory stimuli are perceived (if you victimize yourself you'll be attacked)

Front 36

Schemas

Back 36

Schema: Enduring beliefs and expectations
Experiences are filtered through Schemas allowing for predictability.
Makes it possible to perceive a stimulus completely different to how someone else would.

Front 37

Motivated Perception

Back 37

Motivated Perception: We tend to perceive what we want to. Supporting our own Schema.
Emotions and motivations influence processing of sensory stimuli.