Sensation and Perception Pt. 1 - the intro, visual and auditory system

Sensation

Receiving and detecting signals (stimuli) from the environment.

Perception

The processing, organization and interpretation of sensory signals

Transduction

The process of the sensory receptors turning sensory information into electrical neural signals

Sensory Coding

How our brain interprets that sensation

Stimulus>Receptors>Thalamus>Cerebral Cortex

General pathway for sensory signals

Psychophysics

The scientific study of the relationship between stimuli and the sensation/perception they produce in the mind

Absolute Threshold

the minimum intensity of stimulus that must occur before you experience a sensation (50% detection)

Difference Threshold

The minimum required difference between two stimuli for a person to notice change

Weber’s Law

The amount of difference that can be detected depending on the intensity of the stimuli that is being compared

Just Noticeable Difference (JND)

the minimum detectable difference between two stimuli

Signal Detection Theory (SDT)

a theory that the detection of a stimulus requires a judgement (Hit, miss, false alarm, correction rejection)

Wavelength & Amplitude (visual)

perceived as color; perceived as brightness

Electromagnetic spectrum

a range that shows all types of waves that can emit a color

Iris

A circular muscle that determines the eye’s color and controls the pupils size

Pupil

A dark circle in the center of the eye that determine how much light enters the eye (dilating = opening, contracting = closing)

Cornea

The eye’s thick, transparent outer layer. Focuses the incoming light

Lens

Absorbs and directs incoming light

Retina

The thin inner surface of the back of the eyeball, which contains the sensory receptors that transduce light into neural signal

Fovea

A small region in the retina packed with cone photoreceptors

Rods

A photoreceptor responsible for night vision. Does not support color vision.

Cones

A photoreceptor that provides color vision. Responsible for vision under brighter conditions.

Bipolar cells

The only neurons that connect the outer retina to the inner retina

Ganglion cells

Cells that send signals along their axons from inside the eye to the thalamus. Generates action potential.

Optic Disk

lacks visual receptors which creates blind spots

Optic Nerve

The nerve where all the axons are bundle up. They send visual signals to the brain

Optic Chiasm

where half of the axons in the optic nerves cross

Thalamus and hypothalamus

About 90% and 10% (respectively) of the axons of the visual pathway

Dorsal and Ventral stream

Determines the “what” and “where” of visual processing pathways

Trichromatic Theory

Color vision results from activity in three different types of cones that are sensitive to different wavelengths (3 cones correlating to different wavelengths)

Opponent Process Theory

different types of ganglion cells, working in opposing pairs, create the perception that Red and Green and Blue and Yellow are opposites. The reason why you see after images

Amplitude and Frequency

Volume and pitch, respectively in terms of wavelengths

Outer ear

Where sound waves travel to first before going down the auditory canal

Eardrum

A thin membrane that marks the beginning of the middle ear; sound waves cause it to vibrate

Ossicles

Transfers the eardrum’s vibrations to the oval window

Hammer, anvil and stirrup

amplifies and transmit sound vibrations from the eardrum to the cochlea. What makes up the ossicles

Oval Window

acts as the connection to the inner ear

Inner Ear (fluid-filled cavities)

Holds the cochlea and the vestibular system

Vestibular System

the primary sensory system for balance, spatial orientation and coordinating movement with head position

Cochlea

the primary sensory organ for hearing. Snail-shaped and fluid-filled.

Hair Cells

Sound receptors

Auditory Nerve

transmits sound information from the cochlea to the brain stem

Thalamus

Processes and transmits almost all sensory (except smell)

Auditory Cortex

Located in the temporal lobe. Processes, interprets and organizes sound information

Sound localization

the ability to identify the location of the sound based on volume and timing