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much of what’s going on in our minds happens outside of awareness, in the
cognitive
unconscious
—the unnoticed support machinery that makes our perception, thoughts, and memories
possible. Many processes of the mind unfold in the cognitive unconscious,
but people are aware only of the products that result from those processes.
The scope of what the cognitive unconscious can achieve is evident in cases of brain damage.
From such cases we know that people can remember without being aware they’re remembering, and
they can even perceive without being aware of their perception. Studies of unconscious attribution
also show us the sophistication of the cognitive unconscious—and thus the ability to evaluate
and interpret evidence while being unaware of the process. Introspections are also sometimes
mistaken—when people don’t realize what factor has influenced their thoughts or behavior, or when
they insist that a factor has influenced them, even though we have reason to believe it hasn’t. These
cases suggest that introspection often isn’t a “readout” of internal processes, but the person’s best
after-the-fact estimation of why they acted or felt the way they did.
The cognitive unconscious allows processes that are fast, effortless, and automatic. This suggests
that consciousness may be needed whenever we wish to exercise executive control over our own
thought processes—rising above habit or resisting the temptation of the moment.
THE NEURAL BASIS FOR CONSCIOUSNESS
The
mind-body problem centers on the fact that the conscious mind is a completely different sort
of thing than the physical body. This point raises deep questions about how the brain
makes consciousness possible and how physical events can cause, or be caused by, conscious
thoughts. Many brain areas are needed for consciousness. These include areas that seem to govern
people’s overall level of arousal and alertness; this aspect of consciousness may257 depend on the
thalamus and reticular activating system. The exact content of consciousness depends on diverse brain
sites, and depends on what a person is conscious
of.
Many studies have examined the
neural correlates of consciousness. These studies show, for
example, that the activity of certain brain sites depends on what visual stimulus the person is currently
aware of. Other studies have examined the conscious sensation of “free will” and have identified
patterns of
brain activity that occur before—and so are plausibly the cause of—this conscious sensation.
According to the
global workspace hypothesis, consciousness is made possible by a pattern of
integrated neural activity, in turn made possible by the connections provided by the workspace
neurons, and controlled by the processes of attention. This hypothesis—while speculative—explains
many aspects of consciousness, including its apparent functions.
VARIETIES OF CONSCIOUSNESS
Our conscious state obviously changes when we’re asleep. An important source of evidence
about sleep comes from EEG data, which allow us to distinguish the distinct stages of sleep. People
seem to need an adequate amount of sleep as well as the right amount of both
slow-wave and
REM
sleep
.
One hypothesis is that sleep is a time for our bodies to repair themselves or restore substances
used up while we’re awake. A different hypothesis is that sleep allows neurons to reset their activity
levels or consolidate connections made during the day. A third hypothesis is that sleep is merely the
state in
which animals pass time while digesting, or perhaps it’s just time animals spend when unable to
find food.
Dreams are strongly associated with REM sleep. Dream reports suggest that dreams showcase a
range of ordinary preoccupations, but they also include weird elements like being naked in public.
Many people propose that dreams have hidden meaning; but most researchers suggest that dreams
are just a hodgepodge of activated images, woven together into a narrative either by the sleeping
brain or perhaps later, when the person recalls the dream.
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