Intro & the Chemical Senses Flashcards
What is perception?
Perception is giving meaning to a detected stimulus (interpretation of a sensation)
What is Psychophysics?
The study of the relationship between the private
experience of sensation (psycho) and the outside
world (physics)
What are 2 chemical senses?
Smell = olfaction Taste = gustation
What is the absolute threshold?
An absolute threshold is the level of stimulus energy that is needed to correctly detect the stimulus, 50% of the time (e.g. a ticking watch 6 meters away in silence)
What are the stimuli called that are only detected less than 50% of the time?
Subliminal
What are the stimuli called that are detected more than 50% of the time?
Supraliminal
What is JND?
Just noticeable difference: the smallest amount of physical difference in stimuli before people noticed that there was a difference
What does Weber’s law state?
The JND is proportional to the standard measure (e.g. JND occurs from 40g to 5 grams plus 1 g is noticeable, but in 4kg change isn’t noticed when 1g is added, noticed when 100g are added)
When doesn’t Weber’s law stack up?
When there are incredible small or incredibly large intensities
What does Fechner’s law state?
Our psychological experience of sensations increases less quickly than actual increase in the physical stimulus
What is Steven’s power law?
The relationship between subjective sensation and stimulus intensity follows a power law (and changes depending on the sensation eg. pain increase faster than light)
What are the 3 laws that explore the relationship between sensation and stimulus?
Weber’s JND
Fechner’s Law (equation for JND)
Steven’s Power Law
Which sensation had the highest score on Steven’s Power law and which had the lowest?
Electric Shock (2nd warmth) Brightness (2nd smell)
What is cross modality matching used for?
to determine whether people’s sensations of stimuli intensity is similar or not
What senses are generally similar between people and which generally differ?
Similar: hearing & vision
Differ: smell & taste
What do you call the chemical compounds that we can smell?
Odourants
Where is the centre of smell detection?
at the olfactory epithelium
What does the olfactory epithelium contain?
olfactory receptor cells
olfactory sensory neurons (OSNs)
How many OSN do we have?
Olfactory sensory neurons: around 20 million
How does the olfactory system work?
Each smell activates a few different OSNs at different weightings which are sent to the glomeruli
What are glomeruli?
cells which coordinate information from the OSN and pass it on to other cells
Are OSN axons fast or slow?
Slow
What is the effect of personal experience on smell perception?
it changes the pattern of activity in the glomeruli
What is proof that odour hedonics (pleasant vs unpleasant) are largely learnt?
Babies don’t find the smell of sweat or faeces unpleasant
Why is smell disconnected from language?
olfactory information bypasses the thalamus (the centre of language) and they are processing in different hemispheres
List 3 findings about smell and memory.
- memories of smell are more durable and stable over time
- smell tends to produce more emotionally intense memories
- memories triggered by odours activate the amygdala more than memories cues from other sources
What factors affect our sense of smell?
genetics experience culture gender age
What are 2 examples of an androstenone smell?
sweat
saliva
What are pheromones?
chemicals emitted by one member of a species that triggers a physiological or behavioural response in another member of the same species
Do humans have pheromones?
Not really as they cannot voluntarily release chemicals but we can detect them.
What are chemosignals?
chemicals released by humans and detectable by the olfactory system that have an effect on the mood, behaviour, hormonal status and/or sexual arousal of other humans
What is flavour made from?
taste and smell
Can you identify foods by taste alone?
Not as well
What are the 4 basic tastes?
Sour
Salty
Bitter
Sweet
What is salt important for in our bodies?
nerve and muscle function
Why do we have an innate tendency to avoid foods that are bitter?
because it usually indicates poison (particularly avoid during pregnancy)
What are the equivalent of pheromones in humans?
chemosignals
What produces the Umami taste?
MSG (Monosodium glutamate)
What are the specialised taste receptors that are attuned to the umami taste?
L-glutamate receptors
Receptors for animo acids
What does the specific hungers theory suggest?
That we get hungry for the foods that we need in particular sodium and carbohydrates
What makes you a non-taster?
Less fungiform papillae
What makes you a super taster?
More fungiform papillae (taste buds) and the PROP gene (bitterness receptor)
What are fungiform papillae?
taste buds
What is the PROP gene a receptor for?
bitterness
What is amosmia?
the inability to smell
What is aguesia?
in ability to taste
What is sensory matching?
Measuring whether one person’s senses match another persons (eg. in taste, smell, vision or touch)
