 Consciousness
Chapter 3

Sleep Theories
Sleep protects: Sleeping in the darkness when predators loomed about kept our ancestors out of harm’s way.
When darkness made travel treacherous for this guy, he was better off asleep in a cave.
Margaret A. McIntyre

Sleep Theories
Sleep helps us recover: Sleep helps restore and repair brain tissue.
Sleeps allows our poor brains to recover from the rigors of the day.
Credit: Gaetan Lee

Sleep Theories
Sleep helps us remember: Sleep restores and rebuilds our fading memories.
We don’t learn through osmosis, but there is evidence for sleep-related memory consolidation…
Credit: Meena Kadri

Sleep Theories
Sleep helps us remember: Sleep restores and rebuilds our fading memories.
In one study, participants performed better on a memory test after an interval of sleep than after an equal interval of being awake.
Credit: Meena Kadri

Sleep Theories
Sleep may play a role in the growth process:
During sleep, the pituitary gland releases growth hormone. Older people release less of this hormone and sleep less.

 Consciousness
Sleep and Dreams
Dreams

Fuseli, The Nightmare (circa 1782)
We all dream. The average person spends about 600 hours per year, dreaming some
1500 dreams.

Fuseli, The Nightmare (circa 1782)
For both men and women, 80% of dreams are marked by at least one negative event, such as being attacked, pursued, or rejected. Most dreams incorporate previous days’ experiences and preoccupations.

Dream Theories
Wish Fulfillment –
Dreams provide a
“psychic safety valve” through which we express unacceptable feelings, and fulfill forbidden wishes.
Credit: Max Halberstadt

Credit: Diliff
Freud believed that our dreams are symbolic, and that interpretation of the “latent content” of dreams is critical to uncovering these forbidden wishes and desires. For example, he believed that long, cylindrical objects are symbolic of the male reproductive organ.

Rat in Morris Water Maze
Credit: http://flickr.com/photos/jepoirrier/139971105/in/set-72057594105461945/
Information Processing-
Dreams play a role in filing away memories.
Consistent with this theory, hippocampal place cells that fire as a rat learns a maze also fire during REM sleep.

Physiological Function –
Brain activity during REM sleep provides the brain with periodic stimulation, and especially in infants, this may help to establish neural pathways. And, in fact, infants spend much of their sleep in REM.

Credit: National Institute on Aging
Activation Synthesis –
Dreaming is nothing more than the brain’s attempt to make sense of random neural activity that spreads upward through the brain from the brainstem.

 Chapter Review
How do psychologists think about consciousness?
What is the notion of “dual processing”?
What is selection attention, and associated phenomena of inattentional and change blindness?
How do we sleep, and why do we sleep and dream?

 Chapter 3 Review
Question(s) from textbook on material not covered in class:
Hypnosis (pp. 109-112)