Psychology2016

114 CHAPTER 3

of taste sensations, which are further affected by our culture, personal expectations, and

past learning experiences. For example, boiled peanuts are not an uncommon snack in

parts of the southern United States, but the idea of a warm, soft and mushy, slightly salty

peanut may not be appealing in other parts of the country. The cortical taste areas also

project to parts of the limbic system, which helps explain why tastes can be used for both

positive and negative reinforcement (Pritchard, 2012). to Learning Objective 5.5.

Just as individuals and groups can vary on their food preferences, they can also

vary on level of perceived sweetness. For example, obese individuals have been found to

experience less sweetness than individuals who are not obese; foods that are both sweet

and high in fat tend to be especially attractive to individuals who are obese (Bartoshuk

et al., 2006). Such differences (as well as genetic variations like the supertasters) compli-

cate direct comparison of food preferences. One possible solution is to have individuals

rate taste in terms of an unrelated “standard” sensory experience of known intensity,

such as the brightness of a light or loudness of a sound or preference in terms of all plea-

surable experiences, and not just taste (Bartoshuk et al., 2005; Snyder & Bartoshuk, 2009).

Turning our attention back to how things taste for us as individuals, have you ever

noticed that when you have a cold, food tastes very bland? Everything becomes bland

or muted because you can taste only sweet, salty, bitter, sour, and umami—and because

your nose is stuffed up with a cold, you don’t get all the enhanced variations of those

tastes that come from the sense of smell.

The Sense of Scents: Olfaction

3.11 Explain how the sense of smell works.

Like the sense of taste, the sense of smell is a chemical sense. The ability to smell odors is

called olfaction, or the olfactory sense.

The outer part of the nose serves the same purpose for odors that the pinna and ear

canal serve for sounds: Both are merely ways to collect the sensory information and get it

to the part of the body that will translate it into neural signals.

The part of the olfactory system that transduces odors—turns odors into signals the

brain can understand—is located at the top of the nasal passages. This area of olfactory

receptor cells is only about an inch square in each cavity yet contains about 10 million

olfactory receptors. (See Figure 3.15.)

olfaction (olfactory sense)
the sensation of smell.

Figure 3.15 The Olfactory Receptors

(a) A cross-section of the nose and mouth. This drawing shows the nerve fibers inside the nasal cavity that

carry information about smell directly to the olfactory bulb just under the frontal lobe of the brain (shown in

green). (b) A diagram of the cells in the nose that process smell. The olfactory bulb is on top. Notice the cilia,

tiny hairlike cells that project into the nasal cavity. These are the receptors for the sense of smell.

Olfactory bulb

Nerve fiber

Receptor cell Cilia Supporting cell

Olfactory bulb

Cilia of olfactory

receptor cell

Olfactory

epithelium

CC