Sensation Flashcards
Define sensation
An internal state produced when out senses gather information about the outside world
What are the 4 stages of conversion
Accessory structures
Transduction
Sensory nerves
Sensation
What are accessory structures
E.g. eyes and ears
What is the process of transduction
Physical energy is picked up by receptors and is converted into neural energy, which receptors respond to.
What is the path of the sensory nerves
Thalamus to various parts of the cortex
When is a sensation produced
When the message reaches the brain
Define psychometrics
Measuring our senses and their thresholds
What does the term Noise mean
A random excitation or inhibition of neurons that either increase or decrease the sensed intensity of a physical stimulus
What are some implications of noise
Noise may not always produce the same internal sensation
Physical signal does not equal sensation
What is the Absolute threshold
Detecting a stimulus 50% of the time
What is Weber’s law of difference threshold
The smallest amount of change in a stimulus before a change is detected
What is Webers fraction within the law
Change of intensity of stimulus/intensity of standard = C
What is background intensity directly proportional to?
The difference threshold
What is hearing based of?
Soundwaves
Define pitch
Frequency of waves (Hz)
Define volume
Amplitude of waves (Decibels)
Define complexity
Nature of the sound (timbre)
What is the place theory
Various places on the basilar membrane vibrate more depending on the pitch
Where is a low frequency detected in the ear
Apex
Where is high frequency detected in the ear?
At the base
What has research found that has artificially stimulated areas of the basilar membrane
Caused sensations of hearing different pitches
What do individuals who cannot hear certain pitches have damage to?
Basilar membrane
What is a problem of the place theory
Below 100Hz no specific place of the membrane vibrates more than the rest
Describe the frequency theory
The higher the frequency of the sound the faster it vibrates
What is the most important factor within the frequency theory
The rate that the hair cells are stimulated
What is a problem with the frequency theory?
Above 1000Hz, the cells go into refractory period as they cannot fire any faster.
What is the frequency and volley theory?
Groups of hair cells fire in alternation to send a higher frequency of signal to the brain.
What is a problem with the frequency and volley theory?
Extremely high frequencies require overly complex teamwork
What does vision define?
Physical energy
What is light measured in
Manometers
What is the electromagnetic spectrum
Differing wavelengths
X rays
1-10Nm
Ultraviolet
101Nm (we only see part of this spectrum)
Infrared
103Nm (We only see part of this spectrum)
Radar
105 Nm
FM radio
109 Nm
TV
1011Nm
am Radio
1012Nm
Violet
400Nm
Blue
500Nm
Green
570Nm
Yellow
600Nm
Orange
650Nm
Red
700Nm
Where are photoreceptors found
In the retina
What do photoreceptors contain?
Photopigment
What do photopigments do
Break down light projected onto photoreceptors, initiating transition of information to the brain, and then breaks down itself (becoming lighter)
What are the two types of photoreceptors
Rods
Cones
When are rods of use?
When looking at dim light with no colour information
Where are rods located?
On the Fovea
What do rods contain
Rhodopsin
When are cones of use?
When looking at bright light with lots of detail and colour information
What do comes contain
Iodopsin
How many types of cones are there
3
What theory describes colour vision
Trichromatic theory
What are colours of the spectrum
Colours that can be made of either a unique wavelength of light or a combination of unique wavelength.
What are primary colours?
Colours that produce and colour on the spectrum when combined with the right amount.
What are the subtractive pigments
Blue, red and yellow
What are the additive lights?
Red, blue and green.
Comes sensitive to short wavelengths produce a sensation of?
Blue
Cones that are sensitive to medium wavelengths produce a sensation of?
Green
Comes that are sensitive to long wavelengths produce a sensation of?
Red
What happens when mixing colours
More than one type of iodopsin is bleached
What does the breakdown of combinations of Iodopsin produce?
A sensation of other colours on the spectrum.
How many types of iodopsin do dichromatic colour blind people have?
2
Blue and green
Or
Blue and red
How many Iodopsin do monochromatic colour blind people have?
One - can only see shades of monochrome
Problems with Dichromatic colour blindness in supporting the trichromatic theory
Dichromats can see yellow which is produced from bleached red and green Iodopsin
How does information travel from the photoreceptor to produce a sensation
Information from rods and cones are conveyed to ganglion cells, via bipolar cells, which send information to the optic nerve.
What is known as the blind spot of the eye
The optic disk
Where does information from the eye meet?
Optic chiasm
What does the optic chiasm do?
Re-routes information to the thalamus which is sent to the visual cortex in the occipital lobe.
What are the three receptors involved in touch?
Temperature, pressure and pain
What do temperature and pressure have in common
They are both relative
What is felt at 32 degrees
Neither cold or hot
Where does information from the left visual field go?
To the right cerebral hemisphere.
Where does information from the right visual field go to?
Left cerebral hemisphere
What substance provides pain
P
What decreases pain
Endorphins
How do electrodes release endorphins to reduce pain
Stimulating parts of the brain or in anticipation of pain
What chemicals produce a physiological response to smell when secreted into the body?
Olfactory sense pheromones
What percentage of the population lose their sense of smell?
8%
What is smell closely linked to
Taste
What are the main taste buds?
Bitter, salty, sour, and sweet
What does taste sensation act similarly to?
Colour sensation
What happens with a different ratio of output from a few different types of receptor cells
Can produce a multitude of sensations
What other factors influence taste?
Smell, mood and texture
