sensation and perception

sensation

The process of receiving stimulus energies from the external environment

transduction

The process of transforming physical energy into electrochemical energy (action potential)

perception

The process of organizing and interpreting sensory information

absolute threshold

The minimum amount of energy an organism can detect 50% of the time

difference threshold

ability to tell the difference between a stronger or weaker stimuli

Difference threshold operates according to

Weber's Law

Weber's Law (just noticeable difference)

Two stimuli must differ by a constant minimum percentage (not a constant amount) to be perceived as different, Fechner helped create this

Selective Attention

you choose to pay attention to some stimuli over others

Inattentional blindness

we miss background information when we heavily concentrate on one thing (gorilla experiment)

Change Blindness

we are blind to subtle changes in the scope of a larger picture (Whodunnit)

Cocktail party effect

we filter out irrelevant info while focusing on one important item - but we still process all the info in case something relevant happens

signal detection theory

- Proposes that the detection of stimuli involves a decision process as well as a sensory process
- Assumes no absolute threshold
- Detection depends on experience, expectations, motivation, and alertness

Dichotic listening task

When receiving info in both ears we can choose to pay attention to only one side - and will ALMOST completely ignore the other side

Sensory Receptors

Specialized cells that detect and transmit sensory information to the brain

cornea

protects the eye

iris

(colored part of the eye) - muscle that controls the pupil

pupil

(black part of your eye) - controls how much light enters the eye

lens

uses visual accommodation: adjusting the curvature of the lens to focus the image onto the retina

retina

contains photo receptors

fovea

spot on retina that contains mostly cones - source of your best vision (called visual acuity)

rods

- Black and white vision
- Function well in low illumination
- Humans have ≈ 120 million rods

cones

- Color vision
- Operate best under high illumination
- Humans have ≈ 6 million cones

trichromatic theory (young-Helmholtz theory)

- three types of cones, blue, green, red
- ratio of activity in the three types of cones yields our experience of a particular color

Color Blindness

Typically a sex-linked trait (carried on the Y chromosome), between 8 and 10% of male population has some version of color blindness while 1% of women do

most common color blindness

red and green

Opponent-process theory

three different receptors (blue-yellow, red-green, black-white), overactivating the cell causes the opposite paired color to be seen

Primary visual cortex

occipital lobe, does initial visual processing

Wavelength

hue / color

saturation

Intensity (brightness)

eye cell layers

rod and cone, bipolar, ganglion, optic nerve

Feature Detectors: Hubel & Wiesel

- Highly-specialized cells in the visual cortex (part of the occipital lobe)
- Size, shape, color, movement, or combination

mirror neurons

Neurons that fire when observing behaviors, triggering the same behavior

Parallel Processing

visual processing simultaneously of - color, motion, shape, and depth

Perceptual Constancies

Recognition that objects do not physically change despite changes in sensory input, Size, Shape, and Brightness Constancies

Perceptual Set (context effects)

Predisposition/readiness to see something a particular way

bipolar cells

cells that combine signals from the rods/ cones

ganglion cells

cells whose axons make up the optic nerve

optic nerve

nerve that carries action potentials

optic chiasm

where the optic nerves cross from left to right (and vice versa) hemispheres

outer ear

pinna, auditory canal

middle ear

tympanic membrane (ear drum), middle ear bones (ossicles: hammer/malleus, anvil/cincus, stirrup/stapes)

inner ear

oval window, cochlea

wavelength

distance between peaks in soundwaves, perceived as pitch

amplitude

height of soundwave, perceived of loudness

timbre

mixture of wavelengths and complex, perceived as tone saturation

audition

the sense or act of hearing

decibels

A unit of measurement of loudness/amplitude

hertz

Unit of measurement for pitch/frequency in cycles per second

Frequency

the number of complete wavelengths that pass a point in a given time

high frequency vs low frequency

high amplitude vs low amplitude

ultrasound

Sound waves with frequencies above 20,000 Hz.

Pathway of auditory information

pinna, auditory canal, tympanic membrane, middle ear bones, oval window, cochlea, auditory nerve, thalamus, temporal lobe (most info crosses to other hemisphere)

place theory of hearing (used for sounds above 4000 Hz)

the theory that different areas of the basilar membrane respond to different frequencies (the frequency of sound is correlated with the part of the basilar membrane showing a peak response)

frequency theory of hearing (used for sounds below 4000 Hz)

the theory that the entire basilar membrane acts like a microphone, vibrating as a whole in response to a sound (patterns of neural firing "match" the actual frequency of a sound)

how do we locate sounds

Sound waves strike one ear sooner and more intensely than the other. The brain analyzes the minute differences in the sounds received by the two ears and computes the sound's source.

how does sound grouping impact our perception?

if sounds comes from one location, we think they're from the same source; if they come from different locations, we think they're from different sources

sensorineural hearing loss

hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness

conduction hearing loss

hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea

pinna

the outer ear structure of flesh and cartilage that sticks out from each side of the head, collects and focuses sounds

auditory canal

outer ear area that sound waves pass through to reach the eardrum

tympanic membrane (eardrum)

the membrane at the end of the ear canal that relays vibrations into the middle ear

middle ear bones (ossicles)

malleus (hammer), incus (anvil), stapes (stirrup)

hammer, anvil, stirrup

the three small bones in the middle ear that relay vibrations of the eardrum to the inner ear

cochlea

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

oval window

membrane at the entrance to the cochlea through which the ossicles transmit vibrations

semicircular canals

three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with body movement (help maintain balance)

basilar membrane

a structure in the inner ear that undulates when vibrations from the ossicles reach the cochlear fluid

Organ of Corti

Center part of the cochlea, containing hair cells, canals, and membranes

hair cells

specialized auditory receptor neurons embedded in the basilar membrane

bottom-up processing (feature analysis)

we use only the features of the object itself to perceive it

top-down processing

a progression from the whole to the elements

gestalt Psychology

The whole is greater than the sum of its parts

Figure Ground

The tendency to organize the visual field into objects (figures) that stand apart from surroundings (back ground)

Closure

tendency to mentally fill in gaps

proximity

tendency to mentally group objects together that are near each other

similarity

tendency to mentally group objects together that look similar

continuity

tendency to mentally group objects that follow a common path

visual capture

The tendency for vision to dominate your senses.

McGurk Effect

Occurs when the visual system overrides (visual capture) the auditory system, causes you to "hear" either what you see or combo of what you see and hear

Interposition (overlap)

items overlapping appear closer

relative size

if two objects are normally similar in size, the one that is smaller appears further away

relative clarity

hazy objects seem further away

texture gradient

closer objects have more detailed textures

relative height

things higher in the field of vision appear further away

monocular cues

depth cues, such as interposition and linear perspective, available to either eye alone

Muller-Lyer Illusion

illusion of line length that is distorted by inward-turning or outward-turning corners on the ends of the lines, causing lines of equal length to appear to be different

linear perspective

parallel lines appear to converge with distance

Relative motion (or motion parallax)

Objects closer to a fixation point move faster and in the opposite direction of your own motion, Objects farther from the fixation point move slower and in the same direction of your own motion

binocular cues

depth cues, such as retinal disparity, that depend on the use of two eyes

retinal disparity

a binocular cue for perceiving depth by comparing images from the retinas in the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object.

convergence

A binocular cue for perceiving depth; the extent to which the eyes converge inward when looking at an object

Pain (nociception)- Gate-control theory

We have a "gate" to control the amount of pain experienced

acupuncture

the needles stimulate nerve fibers that lead to a closing of the pain gate.

Kinesthetic System (proprioception)

Cells located in your joints, tendons, and muscles sense your body position and tells your brain where you are

vestibular system

The inner ear and brain structures that afford a sense of equilibrium (balance)

Taste (gustation)

- Receptors on tongue: papillae
- Five taste qualities: sweet, sour, bitter, salty, umami (savory)
- All tastes are located throughout the tongue

Smell (olfaction)

- Processed by Olfactory epithelium in the OLFACTORY BULB
- By-passes thalamus and goes straight to the limbic system

Sensory Adaptation

Diminished sensitivity as a result of constant stimulation

sensory habituation

Process occurs in brain, not the individual body receptors. Over time you become less aware of something outside your body (living next to train)