Teaching With the Brain in Mind

ence. Many students don’t have a better use of
their time than staying after class. And if staying
after is a miserable experience, the bad feelings
“contaminate” the student’s overall opinions about
the teacher, classroom, and school. That damage
can be deadly to long-term motivation and morale,
so generally it’s not worth it to detain students.
Many students don’t respond to lowered grades or
a loss of privileges, so those threats can be tenuous.
In short, on a purely behavioral level, threats
make little sense. But what is happening on a more
biological level?
Stress and Learning
When we feel stressed, our adrenal glands release a
peptide called cortisol. Our body responds with
cortisol whether it faces physical, environmental,
academic, or emotional danger. This triggers a
string of physical reactions including depression of
the immune system, tensing of the large muscles,
blood-clotting, and increasing blood pressure. It’s
the perfect response to the unexpected presence of
a saber-toothed tiger. But in school, that kind of
response leads to problems. Chronically high cortisol
levels lead to the death of brain cells in the
hippocampus, which is critical to explicit memory
formation (Vincent 1990).
These physical changes are significant. Stanford
scientist Robert Sapolsky found that atrophy
levels in the hippocampus of Vietnam veterans
with PTSD (post-traumatic stress disorder) ranged
from 8 to 24 percent above the control group.
Chronic stress also impairs a student’s ability to
sort out what’s important and what’s not (Gazzaniga
1988). Jacobs and Nadel (1985) suggest
that thinking and memory are affected under
53
How Threats and Stress Affect Learning
stress; the brain’s short-term memory and ability to
form long-term memories are inhibited.
There are other problems. Chronic stress makes
students more susceptible to illness. In one study,
students showed a depressed immune system at test
time; they had lower levels of an important antibody
for fighting infection (Jermott and Magloire
1985). This may explain a vicious academic cycle:
More test stress means more sickness, which means
poor health and missed classes, which contribute to
lower test scores. Figure 6.1 illustrates the differences
between a stressed and an unstressed neuron.
The stressed one has fewer and shorter dendrites.
This deficiency impairs communications with other
dendrites. What caused this dramatic difference?
FIGURE 6.1
How Social Stress Can Affect Neurons
Typical Neuron Taken
from an Animal in a
Dominant Role
Typical Neuron from
One in a Subordinate Role
Copyright © 1989–97 by Techpool Studios, Inc., USA.