Perception - "The Chemical Senses"

Chemoreceptors.

It is believed that taste and smell diverged in the amphebians. Now smell fulfills additional functions, such as assisting in mating through the use of pharamones.

It means that a keen sense of smell is necessary for it's survival.

It means that the animal has a less keen ssense of smell and can still survive and function.

It means that the animal has no sense of smell.

A rat is 8 to 50 times as sensitive to smells as a human. A dog is 300 to 10,000 times more sensitive to smells than a human.

There is no difference in the sensitivity of the receptors. There is just a difference in the overall number of receptors.

We can measure odor detection by finding a detection threshold or a difference threshold.

The olfactometer.

11%.

Human can discriminate between about 100,000 odors, but they cannot label them accurately.

We test for the localization of odors using sniffo-meters.

This is sniffing and scanning that improves performance when localizing odors.

Sobel took college age students out to a field and had them follow the scent of a chocolate bar. Two-thirds or participants could track it, using the same self-correction method that a dog does. This depends on the participant's ability to compare the strength of the scent with two nostrils.

The difference in the strength of a scent between the two nostrils.