78
votes
Accepted
Is there an RGB equivalent for smells?
There are about 100 (Purves, 2001) to 400 (Zozulya et al., 2001) functional olfactory receptors in man. While the total tally of olfactory receptor genes exceeds 1000, more than half of them are ...
- 52.3k
44
votes
Accepted
Are drugs made bitter artificially to prevent being mistaken for candy?
Short answer
A bittering agent may be applied to therapeuticals to prevent pediatric poisonings, but many drugs inherently taste bitter by themselves.
Background
Bitter taste is thought to have ...
- 52.3k
36
votes
Accepted
Why does my room suddenly look 'reddish'? My eyes seem to adapt to color
Short answer
The phenomenon you describe can be explained by the negative afterimage effect, which indeed is elicited by adaptive processes in the retinae.
Background
In the retina there are three ...
- 52.3k
35
votes
Accepted
Did predators evolve eyes first?
Short answer
Complex eyes may have evolved first in predator species, specifically in box jellyfish. Trilobites are another group of animals where complex eyes may have evolved first. The trilobites ...
- 52.3k
33
votes
Accepted
Can one see flickering of a light bulb at 50 Hz?
Short answer
Yes, the flickering of a light bulb may be noticeable, and yes, that's directly related to the mains frequency. However, since the flickering of a bulb is about two times higher than the ...
- 52.3k
28
votes
Accepted
Can we taste electrons?
Short answer
Yes, taste sensations can be generated electrically. However, we cannot taste electrons themselves, as taste-receptor proteins on the taste receptor cells are not activated by electrons. ...
- 52.3k
27
votes
Accepted
Why is loud music much louder after pausing and resuming it?
Hearing is capable of sensory adaptation such that prolonged constant stimulus is perceived as less intense. In hearing, the adaptation to loud sounds is called acoustic reflex and is mediated by two ...
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21
votes
Accepted
How statistically significant was the "sweaty T-shirt" experiment?
First, let's consider the original Wedekind et al (1995) study.
Sample sizes seem reasonable, if the effect is not very noisy:
[...] 49 female students (average age: 25.2 years, s.d. = 4.0) and ...
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20
votes
Accepted
Why does black and yellow indicate danger?
First of all, great question! What you describe here is known as aposematism. Aposematism is the adapation of warning signals against the predator. This word is used for any sound, coloring, and odor ...
- 3,079
20
votes
Did predators evolve eyes first?
AliceD's answer is great but just to address your points 1 and 2.
Eyes are expensive. From a study on fish loosing their vision in caves.
The cost of vision was calculated to be 15% of resting ...
- 301
13
votes
Did predators evolve eyes first?
Eyes evolved multiple independent times in convergent evolution.
Almost all the vertebrates have eyes. Those few that doesn't lost their eyes through evolution and live in deep ocean of in caves where ...
12
votes
Why do I still see a bright light after looking directly at it?
Short answer
The effect you describe is called a negative after image. It can be explained by adaptation effects of the photoreceptors in the eye.
Background
source: Dresden University
Steadily ...
- 52.3k
10
votes
Accepted
What is the smallest touch sensation that a human can feel?
Short answer
The detection threshold of static indentation stimuli on the palm of the hand is approximately 10 to 40 micrometers, dependent on the exact location under investigation.
Background
The ...
- 52.3k
9
votes
Is there an RGB equivalent for smells?
There are many, many more parameters than 200! As an example, look at the nomenclature system for olfactory receptors (ORnXm).
"OR" is the root name (Olfactory Receptor superfamily)
n = an integer ...
9
votes
Accepted
Can a color-blind person see color with filter glasses?
Short answer
Optical filters can optimize color contrast, but never restore color blindness. Filters remove colors, they can never add something. However, glasses like this can prove helpful for ...
- 52.3k
8
votes
Accepted
Can frogs see clearly under and above water?
Short answer
Frogs are nearsighted on land and farsighted under water.
Background
Frogs are reported to be nearsighted on land, but farsighted underwater (source: Chegg Study). Nearsightedness (...
- 52.3k
8
votes
Can one see flickering of a light bulb at 50 Hz?
A lamp flickers at 2x the mains frequency, i.e. 100 or 120 Hz, and that is typically not noticeable to human eyes. It is visible to chicken and insects.
That being said, a low quality lamp or a lamp ...
- 181
7
votes
Accepted
Why doesn't the ambient lighting condition change the perception of colors we see on a monitor?
The phenomenon you are referring to is color constancy: The apparent hue of a reflective surface remains constant even when changes in the spectral power distribution of the illuminant alter the ...
- 52.3k
7
votes
Accepted
Perception of white in the absence of rods
Short answer
Cones mediate the perception of white in photopic conditions. Rods mediate the perception of white in scotopic conditions. The rod system is not needed for cones to mediate white ...
- 52.3k
7
votes
Accepted
What would happen if you "rewired" your eyes with your nose?
"Rewiring" the brain isn't quite that simple: simply splicing a nerve to another doesn't necessarily mean the axons of that nerve will then grow into area. I am unaware of any studies that cross these ...
- 44.1k
7
votes
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Why do humans not have a powerful sense of smell?
Humans' poor sense of smell is a myth, borne of 19th century speculation rather than actual data. This is described in an excellent recent paper in Science , "Poor human olfaction is a 19th-century ...
6
votes
Accepted
What causes the tonotopic organization of the inner ear?
The frequency tuning in the cochlea is due to a number of factors.
The primary factors of cochlear frequency tuning are generally ascribed to the passive physical characteristics of the basilar ...
- 52.3k
6
votes
How statistically significant was the "sweaty T-shirt" experiment?
@bshane has already provided an excellent answer to the question. However, I just found a recent review published in Molecular Ecology (Winternitz et al., 2016) in which the authors performed a ...
- 2,868
6
votes
Why do humans not have a powerful sense of smell?
There are several factors in human.
we are upright, which brings the nose just about as far away for scents as it can get, you want your nose as close to the ground as possible for the most efficient ...
- 14.3k
6
votes
Accepted
Why is peripheral vision not bleached by daylight?
Short answer
In photopic lighting, peripheral vision is mediated by cones.
Background
The rods are indeed saturated at daylight, and even at twilight (source: Nature). However, the cones are active ...
- 52.3k
5
votes
Accepted
Are resonances the reason receptors work?
Photoreceptors themselves dont act as oscilators, a single receptor is either 'on' or 'off' - it does not respond differently to different wavelenghts. Humans have Trichromatic vision, which means ...
- 4,391
5
votes
Understanding the "Waterfall Illusion"
The motion after-effect (MAE) is believed to be primarily due to adaptation of direction sensitive cells in the middle temporal area (MT) (Fig. 1.). The directional cells in this area of the cortex ...
- 52.3k
4
votes
How can some animals see ultraviolet or infrared light?
Short answer
In mammals dedicated UV cones have been found, as well as photoreceptors with secondary peak-sensitivity in the UV range. In fact, human blue cones are sensitive to near-UV.
Background
...
- 52.3k
4
votes
How can bobcats feel the mice under the snow?
You can smell roughly where your pan is cooking, but you can hear it with more precision, in order to pin point something you would tend to use your ears, especially if it is under snow.
Cats use all ...
- 10.3k
4
votes
Accepted
What causes Pseudomonas fragi to smell sweet?
The strawberry-like odour that you perceived is mainly attributed to three ethyl esters, namely the ethyl esters of butyric, hexanoic and 3-methylbutanoic acid.
There are other odour-active volatiles ...
- 1,509
Only top scored, non community-wiki answers of a minimum length are eligible