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Is daydreaming, rather than being just a form of goofing off, the mechanism by which the brain processes learn material while awake? Would this process be akin to needing actual sleep to process memories? If so, could this account for the eccentricity of people such as Thomas Edison who were always taking catnaps — Grady, Navarre, Florida

We don't know why people daydream. Your processing-memories suggestion, though, is a fairly good guess.

To clear up nomenclature: daydreams are thoughts we have when we voluntarily shift from thoughts stimulated by our senses or the task at hand to thoughts our brain generates, independently.

Recently a team of neuroscientists identified what part of the brain implements daydreaming. In January 2007, the team (composed of researchers from Dartmouth College, Harvard, the University of California and University of Aberdeen) reported on a network of regions in the brain's cortex that are active when we daydream.

Moreover, when we stop daydreaming to focus on an intense task, like working a puzzle, we essentially stop using the 'daydream' network. The researchers found that a brain focusing on a "high executive demand" task lessens activity in the 'daydreaming' network — essentially turning it off, says Malia F. Mason , presently a professor at the Columbia School of Business and a member of the team. The study was part of her dissertation at Dartmouth.

Furthermore, other researchers at the Washington University in St. Louis found one task that the brain both focuses on, and uses the daydreaming network. People trying to remember what they had for breakfast, for example, might use part of the daydreaming network, says team member Cindy Lustig . So, perhaps autobiographical memory and daydreaming are related. We don't know yet.

In fact, Mason and the rest of the team muse why mind-wandering thoughts occur at all. Maybe daydreaming helps us carry out mundane tasks, because a wandering mind is still aroused. Or, perhaps daydreams are a kind of "mental time travel" that help us tie together our past, present and future experiences. Or, maybe the mind wanders "simply because it can."

Also, the mind wanders to solve problems, as perhaps Thomas Edison's mind did. Mark Twain and Edgar Allan Poe wrote stories based on their daydreams. The chemist Friedrich Kekule, in that half-awake state we enter before falling asleep, daydreamed of two serpents biting each other's tail, and forming a ring. He jolted awake, and saw the answer to how a benzene molecule is structured. It's a ring By the way, we all daydream for about one-third of our waking hours, according to Eric Klinger, a clinical psychologist at the University of Minnesota.

Further Reading:

What is a dream? WonderQuest

Wandering minds: the default network and stimulus-independent thought, by Malia F. Mason, Michael I. Norton, John D. Van Horn, Daniel M. Wegner, Scott T. Grafton and C. Neil Macrae. Science, 315, 393 (2007).

Brain's 'resting' network offers powerful new method for early Alzheimer's diagnosis , by Gerry Everding on work done by Cindy Lustig, Abraham Z Snyder, Mehul Bhakta, Katherine C O'Brien, Mark McAvoy, Marcus E Raichle, John C Morris, & Randy L Buckner (2003) and reported in Functional deactivations: Change with age and dementia of the Alzheimer type.

Consciousness and Eric Klinger's daydreaming time study Inventing benzene , Engines of our Ingenuity

Fast Answer:

What does an octopus do when a predator threatens it? Brittany, Orange, New South Wales, Australia

It depends on the octopus. The extremely toxic blue-ringed octopus displays his brilliant blue rings to warn a predator off.

"Many octopus have a pair of 'eye spots' that they can flash", says Roy Caldwell , professor of integrative biology at the University of California, Berkeley. This may startle predators just as the eyespots on a moth do.

Most octopuses release a reservoir of dark inky dye, which might serve as a smoke screen and/or be noxious disabling the predator's chemosensory organs. Other species can release ink mixed with mucus. This forms a brown or black glob that hangs in the water and looks somewhat like the octopus. Often, as the octopus releases the deceptive glob, it changes colour (usually to white) and gets away. The predator attacks the glob and gets nothing more than a mouth full of bad tasting ink.

Octopuses also can change their skin coloration to go unnoticed.

Several octopus species drop their arms off their body when attacked. "The wiggling autotomized arms will even lock onto the predator with its suckers," Caldwell says. "This is usually sufficiently distracting to allow the octopus to escape." Re-growing lost arms is a snap for an octopus.