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(MacPherson et al., 2016). And if responsible for the absence of birthday cake, they may feel
no regret (Bault et al., 2019).
Frontal lobe damage also can alter personality and remove a person’s inhibitions. Con-
sider the classic case of railroad worker Phineas Gage. One afternoon in 1848, Gage, then
25 years old, was using a tamping iron to pack gunpowder into a rock. A spark ignited the
gunpowder, shooting the rod up through his left cheek and out the top of his skull, leaving
his frontal lobes damaged (Figure 1.4-17). To everyone’s amazement, Gage was immedi-
ately able to sit up and speak, and after the wound healed, he returned to work. But the
blast damaged connections between his frontal lobes and the brain regions that control
emotion and decision making (Thiebaut de Schotten et al., 2015; Van Horn et al., 2012).
The previously friendly, soft-spoken man was now irritable, profane, and dishonest. This
Distributed by Bedford, Freeman & Worth Publishers. Not for redistribution.
person, said his friends, was “no longer Gage.” Most of his mental abilities and memories
were intact, but for the next few years his personality was not. (Gage later lost his rail-
road job, but over time he adapted to his disability and found work as a stagecoach driver
Copyright © Bedford, Freeman & Worth Publishers.
[Macmillan & Lena, 2010].)

Figure 1.4-17
A blast from the past
(a) Phineas Gage’s skull was kept as a
medical record. Using measurements
and modern neuroimaging techniques,
researchers have reconstructed the
probable path of the rod through Gage’s Warren Anatomical Museum in the Francis A. Countway Library of Medicine.
brain (Van Horn et al., 2012). (b) This photo
shows Gage after his accident. (The image
has been reversed to show the features
correctly. Early photos, including this one,
were actually mirror images.) Gift of Jack and Beverly Wilgus

(a) (b)

Studies of other people with damaged frontal lobes have revealed similar impair-
®
AP Science Practice ments. Not only do they become less inhibited (without the frontal lobe brakes on their
Research impulses), but their moral judgments also seem unrestrained. Cecil Clayton lost 20 percent
of his left frontal lobe in a 1972 sawmill accident. Thereafter, his intelligence test score
Phineas Gage is a classic example dropped to an elementary school level and he displayed increased impulsivity. In 1996, he
of a case study, a non- experimental
method. A case study hopes to fatally shot a deputy sheriff. In 2015, when he was 74, the State of Missouri executed him
reveal universal principles, but (Williams, 2015).
generalizing its findings requires The frontal lobes help steer us toward kindness and away from violence (Achterberg
further research.
et al., 2020; Lieberman et al., 2019). With their frontal lobes ruptured, people’s moral com-
pass seems separated from their actions. They know right from wrong but often don’t care.
Association areas also perform other mental functions. The parietal lobes, parts of
which were large and unusually shaped in Einstein’s normal-weight brain, enable mathe-
matical and spatial reasoning (Amalric & Dehaene, 2019; Wilkey et al., 2018). Stimulation of
one parietal lobe area in patients undergoing brain surgery produced a feeling of wanting
to move an upper limb, the lips, or the tongue, but without any actual movement. With
increased stimulation, patients falsely believed they had moved. Curiously, when surgeons
stimulated a different association area near the motor cortex in the frontal lobes, the patients
did move but had no awareness of doing so (Desmurget et al., 2009). These head-scratching

76 Unit 1 Biological Bases of Behavior

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