What is sensation?
sensation is detecting physical energy from the environment and converting it into neural signals
o Occurs when specialized receptors in the body are activated allowing various forms of outside stimuli to become neural signals in the brain
o Process by which information from outside world enters brain § Information enters through sensory receptors ( tongue, ear, etc.)
Convert different stimuli into neural activity Consciously or unconsciously
What is Transduction?
Transduction is converting outside stimuli into neural activity.
What is perception?
When we select, organize, and interpret our sensations, the process is called perception. Perception occurs when we give meaning to our sensations, interpreting them.
What are the five senses of transduction?
- Taste (gustation): food molecules chemical signals coming in
- Vision: light (photons)
- Hearing ( audition): sound waves
- Touch (somatosentaion): pressure and temperature
- Smell (olfaction): molecules in the air
Who was Ernest Weber?
Ernest Weber (1795-1878)
o Just noticeable differences- smallest difference between two stimuli that is detectable 50% of the time; whatever the difference might be, it is always a constant
o Ex: lifting a 55lb weight and a 50lb weight and half the time you say there is a difference
What is absolute threshold?
Absolute Threshold: Minimum stimulation needed to detect a particular stimulus 50% of the time.
What is the difference threshold?
Difference Threshold: Minimum difference between two stimuli required for detection 50% of the time, also called just noticeable difference (JND).
What is Weber law?
Weber’s law in humans, difference thresholds (experienced as a jnd) increase in proportion to the size of the stimulus
Two stimuli must differ by a constant minimum percentage to be perceived as different
What are Sublimal Threshold?
Subliminal stimuli are those just strong enough for our sensory receptors to pick them up, but not strong enough for us to be able to detect them
What is habituation?
Habituation is tendency of the brain to stop tending to constant, unchanging information; air conditioning; at the neural level
What is the priming effect?
Priming effect reveals that we can process some information from stimuli too weak to recognize, No powerful enduring effects but really subtle
What are microsacchades?
Microsacchades constant movement of the eyes; tiny little vibrations that people do not notice consciously; prevents sensory adaption to visual stimuli
What is sensory adaptation?
Sensory adaption is the tendency for the sensory receptors to be less responsive to stimulus unchanged; don’t send the signals to the brain
What is transduction?
Transduction is the transformation of stimulus energy into neural impulses.
What is photo transduction?
Photo transduction Conversion of light energy into neural impulses that brain can understand.
Color is determined by wavelength. What is a wavelength?
Wavelength is determined by the length of the wave, distance between wave peeks
The brightness of a color is determined by amplitude and intensity of a wavelenght. What is amplitude and intensity?
- Amplitude is determined by the height of the wave, how high or low the wave actually is
- Intensity is the amount of energy in a wave; determined by amplitude; related to perceived brightness
What determines saturation?
Determined by whether or how much there is a mixture of wavelengths.
What are the parts of the eye?
The parts of the eye are the cornea, iris, lens, and the retina.
What is the cornea?
Cornea Transparent tissue where light enters the eye.
What is the iris?
The Iris is the muscle that expands and contracts to change the size of the pupil for light.
What are the lens?
The lens focuses the light rays on the retina ( through visual accommodation a process by which the eye’s lens changes the shape to help focus near or far objects on the retia)
What is the retina?
Retina Light sensitive inner surface of the eye containing photoreceptor rods and cones plus layers of other neurons (bipolar and ganglion cells that process visual information)
What are rods and cons?
- 6 million
- Low sensitivity to dim light
- Located in fovea
- Color and detail sensitive
- 120 million
- Responsible for peripheral vision
- Allow eyes to adapt to low levels of light; high sensitivity to dim lighting
- Not color or detail sensitive
What are bipolar cells?
Bipolar cells receive information from photoreceptors and transmit them to the ganglion cells which form the optic nerve.
What are optic nerve cells?
Optic nerve: carries neural impulses from the eye to the brain
What is a blind spot?
Blind spot is the point where optic nerve leaves the eye, because there are no receptor cells located here, it creates a blind spot
What is a Fovea?
Fovea is the central point in the retina, around which the eye’s cones cluster.
Describe the process of visual processing?
At the optic chiasm, information crosses and left eye information is sent to right brain and vice versa. Optic nerves connect to the thalamus in the middle of the brain and the thalamus (switchboard of the brain directing sensory information with the exception of smell) to the visual cortex.
What is trichromatic theory?
Trichromatic theory: theory of color vision that proposes three types of cones: red, blue, and green. Light of any color can be matched by the additive mixture of these three primary colors, Most known facts about color blindness are explained well through this theory. Trichromatic is good with explaining how cones work.
What is opponet Process theory.
Opponent Process Theory: based on the idea that there are four primary colors: red, green, blue, yellow. If one member of the pair is stimulated, the other is inhibited. Explains why after image will be the compliment of the color originally stared at.
What is size constancy?
Size constancy: the tendency to interpret an object as always being the same actual size regardless of its distance ( size on retina gets smaller).
What is shape constancy?
Shape constancy: the tendency to interpret the shape of an object as being constant, even when its shape changes on the retina; a gestalt type principle
What is the figure ground principle?
Figure Ground gestalt type principle; tendency to perceive objects as existing on a background
What is perpetual set?
Perceptual set Perceptual expectancy: the tendency to perceive things a certain way because previous experiences or expectations influence those perceptions
What is the difference between top dowm and bottom up processing?
Top down processing: use of pre existing knowledge to organize individual features into a unified whole. Bottom up processing: the analysis of the smaller features to build up to a complete perception.
What is Muller Lyer illusion?
Muller- Lyer illusion is the 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
What are sound waves?
Sound waves are vibration of the molecules of the air surrounding us
What are acoustical transduction?
Acoustical Transduction conversion of sound waves into neural impulses in the hair cells of the inner ear.
What is pitch?
Pitch is determined by the wavelength or frequency (low, medium, high). Wavelength: distance from peak to peak of waves, Frequency: (Hz) cycles of waves per second
•Long wavelengths= low frequency low pitch
•Short wavelength= high frequency high pitch
What is volume?
Volume (loudness) is determined by amplitude, Amplitude is the amount of energy in a wave which relates to perceived loudness, Measured in decibels
- High amplitude= loud sound; low amplitude= quiet sound
- Sound threshold of about 80-90 where prolonged exposure can lead to hearing loss
What is timbre?
Timbre is determined by the purity or the complexity of the tone of the sound (richness).
What is place thoery?
Place Theory suggests that different sound waves stimulate the basilar membrane at different specific places resulting in perceived pitch. Good with high pitch higher than 1000Hz
What is frequency theory?
Frequency Theory states that the rate of nerve impulses traveling up the auditory nerve. Matches the frequency of a tone, thus enabling us to sense a pitch. Imagine you have a sound traveling at 100 Hz so the action potential is traveling at 100Hz down nerve. Good with low pitched less than 1000hz
What is volley priniciple?
Volley principle is the theory of pitch that states that different frequencies cause the hair cells ( auditory neurons) to fire in a volley pattern, or take turns in firing. Good with moderate to high pitch between 40 Hz to about 4000 Hz.
What are the parts of the ear?
The parts of the ear are the outer ear, inner ear, and middle ear.
What is the outer ear?
The Outer ear consists of pinna that collects and funnels sounds. It includes the Eardrum which vibrates when sound hits it.
What is the middle ear?
The Middle ear is the chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup aka ossicular) chain that sends vibrations to the cochlea’s oval window.
What is the inner ear?
The Inner Ear is the innermost part of the ear consists largely of the cochlea, a fluid filled, coiled shaped tunnel that contains receptors for hearing.
How does sound travel through the ear?
As the oval window vibrates, it vibrates the fluid in the cochlea which transmits sound to the basilar membrane and Organ of Corti. This will cause the hair cells to move which will cause them to be excited and send off action potentials down their axons which form the auditory nerve and go to the brain. These messages can be ipsalateral or contralateral. Goes to auditory complex located in temporal cortex.
What is conduction hearing impairment?
Conduction hearing impairment: sound vibrations cannot be passed from the eardrum to the cochlea. Caused by damage to the mechanical system that conducts sound waves to the cochlea. Ex: ear drum punctured or tiny bones broken
What is nerve hearing impairment?
Nerve hearing Impairment problem lies in inner ear or in the auditory pathways and cortical areas of the brain, Caused by damage to cochlea’s hair cells or auditory nerve. Also called nerve deafness, Ex: disease, aging, over‐exposure to loud sounds
What is hearing deficit?
Hearing deficit: older people tend to hear low frequencies well but suffer hearing loss for higher frequencies. This can be accommodated by increasing volume. Ex: playing the high frequency in the hallway to get the kids to class or the high frequency ringtone.
What is the stimulus input of taste?
Chemicals are the stimulus input of taste, The gustatory receptors are clusters of cells responsible for the sense of taste. Mostly located on the tongue; not the bumps but located on the bumps which are called papillae.
What is gusatry transduction?
Gustatory Transduction: conversion of food molecules into neural impulses
What are the basic taste?
Five Basic Tastes:
- Umami: stimulated by glutamate found in MSG monosodium glutamate
What is the Gustatory cortex?
Gustatory cortex insular lobe; parts of frontal, temporal, and parietal lobes folded over it
Describe the process of smell?
- The olfactory cilia are the hair-like structure located in the upper portion of the nasal passages and are responsible for smell
- Chemicals bind to the olfactory cilia
- Olfactory transduction: conversion of chemical molecules in the air into neural impulses by the olfactory cilia
- Olfactory receptors send neural signals related to smell directly
- Olfactory bulb has projections to the limbic system but not the thalamus
What are Olfactory cilia?
Olfactory Cilia are airflow through the mouth and up the trachea can get to cilia.
What are the somesthetic senses?
Somesthetic Senses are body’s senses consisting of the skin sense, kinesthetic sense, and vestibular senses.
What are the vestibular senses?
The Vestibular Sense is sense of movement, balance, and body position. Processed by vestibular organs in the inner ear, Otolith organs for sensing translations, Semicircular canals for sensing rotations.
What are kinesthitic senses?
Sense of the location of body parts in relation to the ground and each other. Processed by proprioceptors in the skin, joints, muscles, and tendons