Understanding Psychology (10th Ed)

Consciousness is the awareness of the sensations, thoughts, 
and feelings we experience at a given moment. Consciousness is 
our subjective understanding of both the environment around us 
and our private internal world, unobservable to outsiders.
In
waking consciousness
, we are awake and aware of our 
thoughts, emotions, and perceptions. All other states of con-
sciousness are considered
altered states of consciousness
. Among 
these, sleeping and dreaming occur naturally; drug use and 
hypnosis, in contrast, are methods of deliberately altering one’s 
state of consciousness. 
In the past, because consciousness is so personal a phenom-
enon, psychologists were sometimes reluctant to study it. After 
all, who can say that your consciousness is similar to or, for that 
matter, diff erent from anyone else’s? Although the earliest 
psychologists, including William James (1890), saw the study of 
consciousness as central to the fi eld, later psychologists sug-
gested that it was out of bounds for the discipline. They argued 
that consciousness could be understood only by relying “unscien-
tifi cally” on what experimental participants said they were 
experiencing. In this view, it was philosophers—not psycholo-
gists—who should speculate on such knotty issues as whether 
consciousness is separate from the physical body, how people 
know they exist, and how the body and mind are related to each 
other (Barresi, 2007; Gennaro, 2004; Rychlak, 1997). 
Contemporary psychologists reject the view that the study of 
consciousness is unsuitable for the fi eld of psychology. Instead, 
they argue that several approaches permit the scientifi c study of 
consciousness. For example, behavioral neuroscientists can 
measure brain-wave patterns under conditions of consciousness 
ranging from sleep to waking to hypnotic trances. And new 
understanding of the chemistry of drugs such as marijuana and 
alcohol has provided insights into the way they produce their 
pleasurable—as well as adverse—eff ects (Baars & Seth, 2009; 
Damasio, 2003; Mosher & Akins, 2007). 
Yet how humans experience consciousness remains an open 
question. Some psychologists believe that the experience of 
consciousness is produced by a quantitative increase in neuronal 
activity that occurs throughout the brain. For example, an alarm 
clock moves us from sleep to waking consciousness by its loud 
ringing, which stimulates neurons throughout the brain as a 
whole (Greenfi eld, 2002; Koch & Greenfi eld, 2007). 
In contrast, others believe that states of consciousness are 
produced by particular sets of neurons and neuronal pathways 
that are activated in specifi c ways. In this view, an alarm clock 
wakes us from sleep into consciousness, because specifi c 
neurons related to the auditory nerve are activated; the auditory 
nerve then sends a message to other neurons to release particu-
lar neurotransmitters that produce awareness of the alarm 
(Tononi & Koch, 2008). 
Although we don’t know yet which of these views is correct, it 
is clear that whatever state of consciousness we are in—be it 
waking, sleeping, hypnotic, or drug-induced—the complexities 
of consciousness are profound.