Sensation Flashcards
What is sensation
senses gather information about the outside world and produce an internal state
Our senses translate physical energy into something the brain can use
How does sensation differ from perception
sensation happens in the beginning stages; perception happens in latter interpretation stages when sensation is translated into knowledge of reality
How many stages of conversion are there
4
What happens in stage 1 of conversion
Accessory structures modify physical stimulus
What happens in stage 2 of conversion
Transduction physical energy is picked up by receptors and
converted into neural energy
What happens in stage 3 of conversion
Sensory nerves send transduced neural energy to the brain. First to the thalamus (relay station) then onto different parts of
the cortex
What happens in stage 4 of conversion
Sensation is produced once message reaches brain
Give examples of sensations
brightness , loudness
Give 2 examples of accessory structures
lens of the eye; outer ear
Why are receptors good at transduction
Receptors respond best to changes in energy levels,
What happens if receptors don’t respond to changes in energy levels
adaptation
what is psychometrics
Measuring the Senses and Thresholds
What is noise
random excitation or inhibition of neurons that either
increases or decreases the sensed intensity of a physical stimulus
What are 3 implications of noise
repeated presentations of the same physical level of
intensity do not always produce the same internal sensation; if a physical signal is doubled, that does
not always produce a doubling of sensation; absolute threshold
What is absolute threshold
lowest level of intensity at which person detects stimulus, defined as the physical intensity at which person can detect the stimulus 50% of the time
Define Weber’s law
difference threshold increases in proportion to the standard; produces a fraction known as Weber’s law:
What is difference threshold
smallest amount of change in a stimulus before a change is detected
Give the equation for Weber’s law
change in intensity of stimulus/intensity of standard = C
what is the pitch of sound waves measured in
hertz (Hz)
What does the frequency of sound waves show
pitch
What is a Weber Fraction
when difference threshold increases in proportion to the standard; produces a fraction
What is the amplitude of a sound wave
volume
what is the volume of sound measured in
decibels (dB)
What is the timbre of a sound wave
the complexity or nature of the sound
What are the 3 theories of hearing pitch
Place theory, frequency theory, frequency and volley theory
What is place theory
different places on the basilar membrane
vibrate more depending on pitch.
What is frequency theory
Basilar membrane is like a guitar string. The higher the
frequency of the sound, the faster it vibrates. It is the rate that the hair cells are stimulated that matters
what is frequency and volley theory
There is alternation in the firing of hair cells (volleying).
Groups of hair cells fire in alternation, sending a higher
frequency of signal to the brain.
Where in the ear does vibration occur on in place theory
basilar membrane
where on the basilar membrane vibrates more at low and high frequencies, respectively?
low= apex high= base (near oval window)
What does research support show about the place theory
artificially stimulating particular areas of the membrane, produces sensations of hearing at different pitches.
Give a problem for place theory
Below 1000 Hz, no specific place on the membrane vibrates more than any other. However, can distinguish between tones that are below that frequency.
Give a problem for frequency theory
Above 1000 Hz, cell cannot fire any faster (refractory period). However, we can distinguish between tones that are above that
frequency
Give a problem for frequency and volley theory
Very high frequencies (e.g., 10,000 Hz) would need very
complex teamwork
What is the physical energy of vision
light
What is light measured in
nanometers
What is the electromagnetic spectrum
the entire range of wavelengths
What is visible light
part of EMG spectrum that eyes can detect as light
What range of light can we see
between UV and infrared; 400nm-780nm
What are in the retina of the eye
photoreceptors
what are in photoreceptors
substance called photopigment
what happens when light is projected onto photoreceptors
photopigment contained within it breaks down, initiating transmission of info to brain
what happens to the photopigment when it breaks down
becomes ‘bleached’ or visibly lighter
what are the 2 types of photoreceptor
cones and rods
what is the photopigment of rods
rhodopsin
what is the photopigment of cones
iodopsin
what are cones used for in vision and what is special about them
vision in bright light; colour information; fine details. Allows for colour vision. each sensitive to different wavelengths of light
what are rods used for in vision
vision in dim light; no colour information; few are
located on the fovea
how many types of iodopsin are there
3
how many types of cone are there and why
3 because of the 3 types of iodopsin
what is the trichromatic theory
retina has three types of receptor cells or cones, which react to light of three different wavelengths - red, green and blue. These cells are responsible for the perception of colours.
What is the trichromatic theory also known as
Young/Helmholtz theory
What is additive colour mixing
commonly used additive primary colours are red, green and blue, and if you overlap all three in effectively equal mixture, you get white light
what sensation do cones sensitive to short wavelengths of light produce
blue
what sensation do cones sensitive to medium wavelengths of light produce
green
what sensation do cones sensitive to long wavelengths of light produce
red
what will colour mixtures cause
more than one type of iodopsin to be
bleached.
what will a combination of iodopsin breakdown produce
a sensation of other colours on the spectrum
Give 2 examples of support for the trichromatic colour theory and why
Dichromatic colour-blindness - Need both red and green iodopsin to distinguish red from green in the world; dichromats can’t make this distinction
Monochromatic colour-blindness - need more than one type of iodopsin to see colour variation.
what is dichromatic colour blindness
only have two types of iodopsin: either blue and green or blue and red.
what is monochromatic colour blindness
only have one type of iodopsin. They see only shades of monochrome -
what are problems for the trichromatic theory
Dichromats can see yellow- the
sensation when both red and green iodopsin is bleached. How can both be bleached if dichromats don’t have either green/red iodopsin?
how are cone photoreceptors organised
opponent pairs
how is sensation created from photoreceptors
Information from rods and cones is conveyed to ganglion cells which send info up the optic nerve to the brain.
The place where optic nerve leaves the eye is known as the optic disk
All information from the eye meets at the optic chiasm which reroutes it to the thalamus, and then to the visual cortex
Information from left visual field goes to right cerebral
hemisphere; information from right visual field to the left
cerebral hemisphere
how do the rods and cones convey information to the ganglion cells
via bipolar cells
What are ganglion cells important for
feature analysis
What does the optic disk create
a blind spot
Where is the visual cortex
the occipital lobe
what is touch
the tactile sense
what are the 3 receptors involved with touch
temperature; pressure; pain
what do pain and temperature have in common
they’re relative
What does it mean for temperature to be ‘relative’
At 32 degrees Celsius (physiological zero)
neither warmth nor cold is felt. Above that temperature, we feel warmth, below that temperature, we feel cold.
However, if skin temperature is raised or lowered, what is sensed as hot or cold changes
What does it mean for pressure to be ‘relative’
Changes in pressure are felt; large adaptation;
don’t feel our wristwatch pressing on our skin except for only a short while.
How is pain produced and reduced
pain pathways have neurotransmitters
Substance P produces pain; endorphins decrease it.
stimulating parts of brain with electrodes can release
endorphins to reduce pain.
how has classical conditioning affected pain
endorphins are released in anticipation of pain
How may acupuncture work
by stimulating endorphins.
what is smell
olfactory sense
what are pheromones
chemicals secreted in the body producing a
physiological response
Give 2 pieces of evidence of pheromones potentially working in humans
Women are asked to dance more often if ovulating
Some evidence that women on the same dormitory floor
“sync up” menstrual cycles (menstrual synchrony)
What does olfaction have
High Adaptation
what does the ability to detect odour drop to over time
30%
What is the link between 8% of people who lose their sense of smell
lose interest in sex
What sense is olfaction linked to and give an example
Olfaction tightly linked to taste
e.g. the inability to smell during a
bad cold reduces taste sensation
What are the main sensors of taste
taste buds
what is umami
the taste of glutamate
What is taste sensation said to operate similarly to and why
the colour sensation of trichromatic colour theory because there are different output ratios froma . few different receptor cell types that produce multiple sensations .
colour has 3 receptor types; taste has 4 or 5
where are taste buds located
on surface of tongue; in trenches between papillae
What do other factors do to gustation
add to flavour of food
