Functions of Dreams

From the same textbook:

"According to Freud, although all dreams represent unfulfilled wishes, their contents are disguised. The latent content of the dream (from the Latin word for "hidden") is transformed into the manifest content (the actual storyline or plot). Taken at face value, the manifest content is innocuous, but a knowledgeable psychoanalyst can recognize unconscious desires disguised as symbols in the dream. For example, climbing a set of stairs might represent sexual intercourse. The problem with Freud's theory is that it is not disprovable; even if it is wrong, a psychoanalyst can always provide a plausible interpretation of a dream that reveals hidden conflicts, disguised in obscure symbols.

Many sleep researchers - especially those who are interested in the biological aspects of dreaming - disagree with Freud and suggest alternative explanations. For example, Hobson (1988) suggests that the brain activation that occurs during REM sleep leads to hallucinations that we try to make sense of by creating a more or less plausible story. As you learned in this chapter, REM sleep occurs when a circuit of acetylcholinergic neurons in the peribrachial region becomes active, stimulating rapid eye movements and cortical arousal. The visual system is especially active. So is the motor system - in fact, we have a mechanism that paralyzes and prevents activity of the motor system from causing us to get out of bed and doing something that might harm us. (As we saw, people who suffer from REM without atonia actually do act out their dreams and sometimes injure themselves. On occasion they have even attacked their spouses while dreaming that they were fighting with someone.)

Research indicates that the two systems of the brain that are most active, the visual system and the motor system, account for most of the sensations that occur during dreams. Many dreams are silent, but almost all are full of visual images. In addition, many dreams contain sensations of movements, which are probably caused by feedback from the activity of the motor system. Very few dreamers report tactile sensations, smells, or tastes. Hobson, a wine lover, reported that although he has drunk wine in his dreams, he has never experienced any taste or smell. Why are these sensations absent? Is it because our "hidden desires" involve only sight and movement, or is it because the neural activation that occurs during REM sleep simply does not involve other systems to a very great extent? Hobson suggests the latter, and I agree with him."


Carlson, Neil. Physiological Psychology. Boston: Pearson, 2005.