Sensation

What is the difference between sensation and perception?

Sensation are the beginning stages, perception is the latter interpretation stages

What do our senses do in order to produce sensation?

Gather information about the outside world

Out senses translate …. into something the brain can use

Physical energy

What are the 4 stages of sensation?

1. Accessory structures modify physical stimulus

2. Transduction: Physical energy in picked up by receptors and converted in neural energy

3. Sensory nerves send transduced neural energy to the brain (Thalamus- relay station, then to different parts of the cortex)

4. Sensation is produced once message reaches the brain

What is neural noise?

Random excitation or inhibition of neurons that either increase or decrease the sensed intensity of a physical stimulus

Repeated presentations of the same physical level of intensity….

Do not always produce the same internal sensation

If physical signal is doubled….

It does not always produce a doubling of sensation

What is the term for the physical intensity at which a person can detect the stimulus 50% of the time?

Absolute threshold

What are the 3 implications of neural noise?

1. Repeated presentation of the same physical level of intensity do not always produce the same internal sensation

2. If a physical signal is doubled, that does not always produce a doubling of sensation

3. Absolute threshold

What is a the difference threshold?

The smallest amount of change in the intensity of a stimulus before a change is detected

What is the Weber fraction?

Different threshold increases in proportion to the standard

What is the ‘standard’ in Weber fraction

The stimulus with original intensity

What is Weber’s law?

Change in intensity of stimulus/ intensity of standard= C(onstant)

What is hearing measured in?

Soundwaves

What part of a wave gives the wave it’s pitch?

Frequency

What is frequency measured in?

Hertz (HZ)

What pitch would come from a frequent wave?

High pitch

What pitch would come from an infrequent wave?

Low pitch

From and to what HZ can humans hear?

20 → 20,000

What part of the sound wave produces volume?

The amplitude

What is volume measured in?

Decibels (dB)

What is timbre?

The complexity/ nature of the sound

Does this wave show a loud or soft sound?

Loud

Does this wave show a loud or soft sound?

Soft

Does this wave show a low or high pitch?

Low

Does this wave show a low or high pitch?

High

Does this wave show a simple or complex timbre?

Simple

Does this wave show a simple or complex timbre?

Complex

What is the eardrum also known as?

Tympanic membrane

What happens in the ear in response to soundwaves?

Eardrum starts to vibrate then the hammer, anvil and stirrup

Stirrup vibrating causes the oval window to vibrate → creates waves within the fluid filled cochlea

Fluid causes the basilar membrane to vibrate

Basilar membrane vibration stimulates nerve cells

= Hearing

What is the collective term for the middle ear bones?

Ossicles

What does place theory argue?

Different parts of the basilar membrane vibrate more depending on the pitch

What parts do high frequencies stimulate?

The base

What part do low frequencies stimulate?

The apex

What has research on hearing pitch done?

Artificially stimulated particular areas of the membrane (cochlear implants), producing sensations of different hearing pitches

Why is it harder for elderly to hear?

Speech is made up on high and low frequencies, they find it harder to hear high ones so it doesn’t really make sense when it’s just low ones

What part of the ear is damaged in elderly people?

The base of the basilar membrane

What is an issue with place theory?

Below 1000Hz, no specific place on the membrane vibrates more than any other, however we can still distinguish between tones below that

What is the alternative theory to place theory?

Frequency (temporal) theory

What does frequency theory argue?

The basilar membrane is like a guitar string, vibrates faster when frequency is high

What is the difference between place theory and frequency theory?

Place theory puts importance on the place of the membrane that is being stimulated whereas frequency theory puts importance on the rate of stimulation

What is a problem for frequency theory?

Above 1000Hz, cells cannot fire any faster (refractory period) however, we can distinguish between above this frequency

What is frequency and volley theory?

There is alternation in the firing of hair cells to send a higher frequency of signal to the brain

What is a problem with frequency and volley theory?

Above 10,000 Hz would need very complex teamwork

Light is ….like

Wavelike

What is light measured in?

Nanometers

Light is part of what spectrum?

The electromagnetic specturm

What is in the electromagnetic spectrum?

X-rays

Ultraviolet

Infrared

Radar

FM radio

TV

AM radio

In between which two types of light is visible light?

Ultraviolet and infrared

The pupil is an opening in your…?

Iris

What is the first layer of the eye called?

The cornea

What is the proper name for the goo behind the cornea?

Aqueous humour

The is the name for the opaque tissue which controls the size of the pupil?

The iris

What does the lens do?

Changes shape to focus the object you’re looking at

What is the liquid called that fills the centre of the eyeball?

Vitreous humour

What is the term for the things that recieve light in the retina?

Photorecpetors

What do photoreceptors contain?

Photopigment

What happens when light is projected onto photoreceptors?

Photopigment breaks down

What does the breakdown of photopigment cause?

Transmission of information to the brain through the optic nerve

What is the term for the breakdown of photopigment?

Bleaching

What are the two types of photoreceptors?

Rods and cones

What type of light are rods responsible for?

Vision in dim light

What is the fovea?

The focal point of your visual field

What type of photopigment do rods contain?

Rhodopsin

Which type of photoreceptor gives colour information?

Cones

What type of light are rods responsible for?

Bright light

What is photopigment in cones called?

Iodopsin

How many types of cone are there?

3

Why are there 3 different types of cones?

Each are sensitive to different types of light (different wavelength)

What can be seen because of different types on cone?

Colour

Which theory was developed by Young & Helmholtz?

Trichromatic theory

What are the primary colours of light?

Red, blue, and green

What type of mixture is light?

Additive

What type of mixture is pigment?

Subtractive

Cones sensitive to short wavelengths produce sensation of:

Blue

Cones sensitive to medium wavelengths produce sensation of:

Green

Cones sensitive to long wavelengths produce sensation of:

Red

What is the support for trichromatic theory?

How many types of iodopsin do people with dichromatic colourblindness have?

2

How many types of iodopsin do people with monochromatic colourblindness have?

1

What is a problem with trichromatic theory?

Dichromats can see yellow → how can this happen if dichromats don’t have either green or red iodopsin?

How are visual receptors organised according to opponent process theory?

Blue/yellow

Red/green

Black/white

Where is information from roads and cones conveyed to?

Ganglion cells

What do ganglion cells do?

Send information up the optic nerve to the brain

What is the name of the place where the optic nerve leaves the eye?

Optic disk

What reroutes visual information to the thalamus and vidual coretx?

Optic chiasm

What are the 3 types of receptors involved in touch?

Temperature

Pressure

Pain

What temperature is physiological zero?

32 degrees Celsius

Which neurotransmitter allows nerves to communicate when in pain?

Substance P

How can you reduce pain?

Stimulate parts of brain with electrodes to reduce endorphins

What are released with the anticipation of pain?

Endorphins

Acupuncture may work by stimulating…

Endorphins

What is the olfactory sense?

Smell

What are pheremones?

Chemical secreted into the body which produce a physiological response

What are women asked to do more when ovulating?

Dance

What may pheromones cause menstrual cycles to do?

Sync up

Over time, the ability to detect odour drops by what %?

30%

What percentage of people who lose sense of smell also lose interest in sex?

8%

What part gives us our sense of smell?

Olfactory mucosa

What are the 4 main group taste buds can sense?

Bitter, salty, sour, sweet (possibly umami)