Module 5: Sensation and Perception

sensation 

sensation 

When sensory information is detected by a sensory receptor,

Sensory receptors

specialized neurons that respond to specific types of stimuli.

transduction

The conversion from sensory stimulus energy to action potential

the vestibular sense

sensory systems that provide information about balance

Proprioception and kinesthesia

sensory systems that provide information about body position and movement

Psychophysics 

the branch of psychology that studies the effects of physical stimuli on sensory perceptions and mental states

German psychologist Gustav Fechner (1801-1887)

The field of psychophysics was founded by ________, who was the first to study the relationship between the strength of a stimulus and a person’s ability to detect the stimulus.

absolute threshold

defined as the intensity of a stimulus that allows an organism to just barely detect it.

Signal detection analysis

a technique used to determine the ability of the perceiver to separate true signals from background noise.

sensitivity

refers to the true ability of the individual to detect the presence or absence of signals

response bias

refers to a behavioural tendency to respond “yes” to the trials, which is independent of sensitivity.

difference threshold (or just noticeable difference [JND]),

refers to the change in a stimulus that can just barely be detected by the organism.

Weber’s law 

maintains that the just noticeable difference of a stimulus is a constant proportion of the original intensity of the stimulus

subliminal stimuli 

(events that occur below the absolute threshold and of which we are not conscious

blindsight

a condition in which people are unable to consciously report on visual stimuli but nevertheless are able to accurately answer questions about what they are seeing.

Perception 

refers to the way sensory information is organized, interpreted, and consciously experienced.

Bottom-up processing

refers to sensory information from a stimulus in the environment driving a process,

 top-down processing 

refers to knowledge and expectancy driving a process

sensory adaptation

we often don’t perceive stimuli that remain relatively constant over prolonged periods of time

 Inattentional blindness 

the failure to notice something that is completely visible because the person was actively attending to something else and did not pay attention to other things

amplitude 

the distance from the center line to the top point of the crest or the bottom point of the trough if a wave

Wavelength 

refers to the length of a wave from one peak to the next.

Frequency 

refers to the number of waves that pass a given point in a given time period and is often expressed in terms of hertz (Hz), or cycles per second.

lower; higher

Longer wavelengths will have ____________frequencies, and shorter wavelengths will have _______frequencies

pitch

The frequency of a sound wave is associated with our perception of that sound’s

20 and 20000 Hz,

In humans, the audible range of sound frequencies is between

louder

Higher amplitudes are associated with ________ sounds

decibels (dB),

Loudness is measured in ________, a logarithmic unit of sound intensity

80 dB to 130 dB:

there is the potential for hearing damage from about how many decibels

Timbre 

refers to a sound’s purity, and it is affected by the complex interplay of frequency, amplitude, and timing of sound waves.

The visible spectrum

the portion of the larger electromagnetic spectrum that we can see

colour

light wavelength is associated with perception of what

red; violet

which colour has longest / shortest wavelength

cornea 

the transparent covering over the eye. It serves as a barrier between the inner eye and the outside world, and it is involved in focusing light waves that enter the eye.

pupil

the small opening in the eye through which light passes, and the size can change as a function of light levels as well as emotional arousal.

iris

The pupil’s size is controlled by muscles that are connected to this, which is the coloured portion of the eye

lens

a curved, transparent structure that serves to provide additional focus .is attached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects.

Accommodation 

refers to the process of changing the curvature of the lens to keep light entering the eye focused on the retina.

fovea, which is part of the retina

the lens will focus images perfectly on a small indentation in the back of the eye known as the

retina

the light-sensitive lining of the eye.

photoreceptor cells (cones)

light-detecting cells that work best in bright light conditions. are very sensitive to acute detail and provide tremendous spatial resolution. They also are directly involved in our ability to perceive colour.

Rods 

specialized photoreceptors that work well in low light conditions, and while they lack the spatial resolution and colour function of the cones, they are involved in our vision in dimly lit environments as well as in our perception of movement on the periphery of our visual field.

night blindness

If your rods do not transform light into nerve impulses as easily and efficiently as they should, you will have difficulty seeing in dim light, a condition known as

retinal ganglion cells.

Rods and cones are connected (via several interneurons) to

The optic nerve

carries visual information from the retina to the brain. Axons from the retinal ganglion cells converge and exit through the back of the eye to form the:

optic chiasm

The optic nerve from each eye merges just below the brain at a point called the

information from the right visual field (which comes from both eyes) is sent to the left side of the brain, and information from the left visual field is sent to the right side of the brain.

where does information go at the point of the optic chiasm

lateral geniculate nucleus (LGN)

a cluster of neurone cell bodies located in the thalamus.

 trichromatic theory of colour vision,

According to this, all colours in the spectrum can be produced by combining red, green, and blue. The three types of cones are each receptive to one of the colours.

 opponent-process theory

According to this theory, colour is coded in opponent pairs: black-white, yellow-blue, and green-red.

afterimage 

describes the continuation of a visual sensation after removal of the stimulus.

depth perception.

Our ability to perceive spatial relationships in three-dimensional (3-D) space is known as

binocular cues

which means that they rely on the use of both eyes to establish depth

binocular disparity,

the slightly different view of the world that each of our eyes receives.

 monocular cues,

cues that require only one eye. Generally, you pick up on depth in these images even though the visual stimulus is 2-D

pinna

which is the visible part of the ear that protrudes from our heads,

the pinna, the auditory canal, and the tympanic membrane

The outer ear includes [3]

ossicles

The middle ear contains three tiny bones known as the 

malleus (or hammer), 

incus (or anvil),

and the stapes (or stirrup)

three ossicles

cochlea 

fluid-filled, snail-shaped structure that contains the sensory receptor cells (hair cells) of the auditory system

hair cells

auditory receptor cells of the inner ear embedded in the basilar membrane.

basilar membrane

a thin strip of tissue within the cochlea.

 temporal theory 

n asserts that frequency is coded by the activity level of a sensory neurone. This would mean that a given hair cell would fire action potentials related to the frequency of the sound wave.

place theory f pitch

suggests that different portions of the basilar membrane are sensitive to sounds of different frequencies. More specifically, the base of the basilar membrane responds best to high frequencies and the tip of the basilar membrane responds best to low frequencies

place coding.

hair cells that are in the base portion would be labeled as high-pitch receptors, while those in the tip of basilar membrane would be labeled as low-pitch receptors

monaural cues

one-eared cues to localize sound

binaural cues

wo-eared cues to localize sound

 Interaural level difference

refers to the fact that a sound coming from the right side of your body is more intense at your right ear than at your left ear because of the attenuation of the sound wave as it passes through your head.

Interaural timing difference

refers to the small difference in the time at which a given sound wave arrives at each ear

Deafness 

the partial or complete inability to hear

congenital deafness

people are born without hearing, which is known as

conductive hearing loss

hearing loss due to a problem delivering sound energy to the cochlea.

blockage of the ear canal,

a hole in the tympanic membrane,

problems with the ossicles,

or fluid in the space between the eardrum and cochlea.

causes for conductive hearing loss include [4]

sensorineural hearing loss (most common form)

hearing loss can be caused by many factors, such as aging, head or acoustic trauma, infections and diseases (such as measles or mumps), medications, environmental effects such as noise exposure (noise-induced hearing loss), tumours, and toxins (such as those found in certain solvents and metals).

a failure in the vibration of the eardrum and/or movement of the ossicles.

With conductive hearing loss, hearing problems are associated with what

These problems are often dealt with through devices like hearing aids that amplify incoming sound waves to make vibration of the eardrum and movement of the ossicles more likely to occur.

how is conductive hearing loss dealt with

 sensorineural hearing loss.

When the hearing problem is associated with a failure to transmit neural signals from the cochlea to the brain

Ménière's disease. (causes sensorineural hearing loss)

disease results in a degeneration of inner ear structures that can lead to hearing loss, tinnitus (constant ringing or buzzing), vertigo (a sense of spinning), and an increase in pressure within the inner ear

Cochlear implants

electronic devices that consist of a microphone, a speech processor, and an electrode array. The device receives incoming sound information and directly stimulates the auditory nerve to transmit information to the brain.

umami, sweet, salty, sour, and bitter.

five basic groupings of taste

umami

is actually a Japanese word that roughly translates to yummy, and it is associated with a taste for monosodium glutamate

Taste buds

formed by groupings of taste receptor cells with hair-like extensions that protrude into the central pore of the taste bud

medulla, thalamus, and limbic system, and to the gustatory cortex, which is tucked underneath the overlap between the frontal and temporal lobes

Taste information is transmitted to the

Olfactory receptor cells

are located in a mucous membrane at the top of the nose. Small hair-like extensions from these receptors serve as the sites for odour molecules dissolved in the mucus to interact with chemical receptors located on these extensions (

olfactory bulb:

a bulb-like structure at the tip of the frontal lobe where the olfactory nerves begin.

to regions of the limbic system and to the primary olfactory cortex, which is located very near the gustatory cortex

From the olfactory bulb, information is sent where?

pheromones

communication often involves providing information about the reproductive status of a potential mate via chemicals

Meissner’s corpuscles

respond to pressure and lower frequency vibrations

 Pacinian corpuscles

detect transient pressure and higher frequency vibrations

Merkel’s disks

respond to light pressure

Ruffini corpuscles

detect stretch

regions of the medulla, thalamus, and ultimately to somatosensory cortex, which is located in the postcentral gyrus of the parietal lobe.

Sensory information collected from the receptors and free nerve endings travels up the spinal cord and is transmitted to where

inflammatory pain

Pain that signals some type of tissue damage is known as

neuropathic pain

pain results from damage to neurones of either the peripheral or central nervous system. As a result, pain signals that are sent to the brain get exaggerated

 congenital insensitivity to pain (or congenital analgesia).

Some individuals are born without the ability to feel pain. This very rare genetic disorder is known as

vestibular sense

contributes to our ability to maintain balance and body posture.

kinaesthesia 

perception of the body’s movement through space

 Gestalt psychology

that perception involved more than simply combining sensory stimuli.