Understanding Psychology (10th Ed)

 mirror neurons 
,
neurons that fi re 
not only when a person enacts a particular behavior but also when a person simply 
observes another individual carrying out the same behavior (Falck-Ytter, 2006; Lepage 
& Theoret, 2007; Schulte-Ruther et al., 2007). 
Mirror neurons may help explain how (and why) humans have the capacity to 
understand others’ intentions. Specifi cally, mirror neurons may fi re when we view 
someone doing something, helping us to predict what their goals are and what they 
may do next. 
The discovery of mirror neurons suggests that the capacity of even young 
children to imitate others may be an inborn behavior. Furthermore, mirror neurons 
may be at the root of empathy—those feelings of concern, compassion, and sympa-
thy for others—and even the development of language in humans (Iacoboni, 2009; 
Ramachandra, 2009; Triesch, Jasso, & Deák, 2007).
FIGURE 3
Changes in the electrical charge in a neuron during the passage of an action 
potential. In its normal resting state, a neuron has a negative charge of about 
–
70 millivolts. 
When an action potential is triggered, however, the charge becomes positive, increasing from 
around 
–
70 millivolts to about 
+
40 millivolts. Following the passage of the action potential, the 
charge becomes even more negative than it is in its typical resting state. It is not until the charge 
returns to its normal resting state that the neuron will be fully ready to be triggered once again.
A sudden, brief reversal
of charge within the
neuron results in an
action potential.
Outside
axon
Inside
axon
Outside
axon
Neuron
Axon
V
oltage (milliv
olts)
Time
–70
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–60
–50
–40
0
30
50
40
Resting
potential