Unit 3: Sensation and Perception

Unit 3

Transduction

Physical energy into chemical energy

Doctrine of Specific Nerve Energies

How stimuli excite different neural pathways gives the perception of our senses

Synesthesia

“Joined perception” sensory disorder,

ex: numbers are colors

Bottom-Up Processing

Starts with sensory input to build complete perception

ex: “What am I seeing”

Top-Down Processing

Guided by experience we see what we expect to see

ex: “Is that something I’ve seen before?”

Selective Attention/cocktail party effect

Tendency to focus on a particular stimulus among the many that we receive

Selective Inattention

At the level of conscious awareness we are only one place at a time so we miss salient objects that are available to be sensed.

Psychophysics

The study of the relationship between the physical characteristics of stimulus and our psychological experience of them

Absolute Threshold

Minimum stimulation needed detected 50% of the time

Difference Threshold

Minimum difference between two stimuli detected 50% of the time

Weber’s Law

Difference threshold is a constant proportion of the specific stimulus

-ex: lights must differ in intensity by 8%, two object must differ in weight by 2%, two tones must differ infrequency by 0.3%

Signal Detection Theory

How motivated are we to detect certain stimuli and what we expect to perceive

Sensory Habituation

Decrease response from repeated exposure

ex: headache goes away cause body is used to it

Sensory Adaption

Neural sensory receptors change to constant stimuli

Sensory Deprivation

Deliberate reduction or removal of stimuli from one or more senses

Sensory Overload

When your five senses take in more information than you can process

Subliminal Perception

Notions we may respond to stimuli beware our level of awareness

Priming

Activation of certain associates influencing one’’s perceptions

ex: patterns like “fill in missing word: red, blue, orange, gr___”

Perceptual Set

Mental predisposition to perceive one thing and not another

Schemas

Beliefs or expectations based on past experiences

Process of light entering the eye

1. Light bounces off object through cornea

2. Passes through pupil size controlled by iris

3. Focused by lens by the process of accomodation

4. Onto retina (center of visual field Fovea)

Blind Spot

Area without receptor cells

Rods

Outside of fovea and sense black and white light, peripheral vision

Cones

Inside of fovea and focus on color, fine detail

Bipolar cells

Transmits signals from photoreceptors to the ganglion cells

Ganglion Cells

Axons form optic nerve

Helmholtz’s Trichromatic Color Theory

Three types of cones, RGB, and all colors are mixed by these colors

-Accounts for types of color blindness

Hering’s Opponent Process Theory

Three pairs of color receptors

-Yellow-Blue

-Red-Green

-Black-White

Negative Afterimage

Sense experience after an image is removed

-see image in previous color

Parallel Processing

Brain delegates the work of processing motion, depth, color to different areas

-after taking scene apart, the brain integrates these subdimensions into the percieved image

Closure

Tendency to finish image when left unconnected

Continuity

Tendency to follow a something through even if interrupted by another sense

Proximity

Tendency to group objects by proximity

Similarity

Tendency to group objects by similar objects

Monocular Cues

Requires only one eye to sense

-Ex: relative size, relative height, aerial perspective, linear perspective, shadowing

Binocular Cues

Requires both eyes
-Ex: stereoscopic vision, retinal disparity, convergence

Auto kinetic illusion

Perceived motion of a single object

Stroboscopic motion

Created by a rapid series of still pictures

Phi Phenonomon

Created by lights flashing in sequence

Timbre

Complex overtones, texture to sound

Place theory

Pitch is location along basilar membrane, explains high pitches

Frequency Theory

Pitch is frequency cillia fire

Volley principle: sequence of firing