Understanding Psychology (10th Ed)

Module 12 
Hearing and the Other Senses 
121
the warning sign of abdominal pain that typically accompanies an infl amed appendix, 
your appendix might eventually rupture, spreading a fatal infection throughout your 
body. 
In fact, all our
 skin senses 
—touch, pressure, temperature, and pain—play a 
critical role in survival, making us aware of potential danger to our bodies. Most of 
these senses operate through nerve receptor cells located at various depths through-
out the skin, distributed unevenly throughout the body. For example, some areas, 
such as the fi ngertips, have many more receptor cells sensitive to touch and as a 
consequence are notably more sensitive than other areas of the body (Gardner & 
Kandel, 2000) (see Figure 5).
Probably the most extensively researched skin sense is pain, and with good rea-
son: People consult physicians and take medication for pain more than any other 
symptom or condition. Pain costs $100 billion a year in the United States alone (Kalb, 
2003; Pesmen, 2006). 
Pain is a response to a great variety of different kinds of stimuli. A light that is 
too bright can produce pain, and sound that is too loud can be painful. One explana-
tion is that pain is an outcome of cell injury; when a cell is damaged, regardless of 
the source of damage, it releases a chemical called substance P that transmits pain 
messages to the brain. 
Some people are more susceptible to pain than others. For example, women 
experience painful stimuli more intensely than men. These gender differences are 
associated with the production of hormones related to menstrual cycles. In addition, 
certain genes are linked to the experience of pain, so that we may inherit our sensi-
tivity to pain (Edwards & Fillingim, 2007; Kim, Clark, & Dionne, 2009; Nielsen et al., 
2008; Nielsen, Staud, & Price, 2009). 
skin senses
The senses of touch, 
pressure, temperature, and pain.
Mean threshold (mm)
0
5
10
15
20
25
30
35
40
45
50
Forehead
Nose
Cheek
Upper lip
Shoulder
Upper arm
Forearm
Breast
Palm
Thumb
1
2
3
4
Back
Belly
Thigh
Calf
Sole
Big toe
Fingers
FIGURE 5 
Skin sensitivity in various 
areas of the body. The lower the average 
threshold is, the more sensitive a body