The Human Brain

Even if you're very ticklish, you probably are incapable of tickling yourself. Learn why.

The term IQ typically refers to a score on a test that measures someone's cognitive ability. What does this test constitute exactly? And does it accurately measure intelligence?

By Alia Hoyt

We've all heard of a "sixth sense" and extra-sensory perception. So how many ways can we actually sense the world around us?

By HowStuffWorks.com Contributors

Every animal sleeps -- some more than others -- but why they do it is a mystery to scientists. Is sleep more than just beauty rest? Could skimping on it kill you? And how much do you really need?

By Marshall Brain

A man in Cornwall, England, went 11 consecutive days without a wink of sleep. Find out how he did it, why he did it and why you shouldn't give it a try.

By Jacob Silverman

Addictions to substances such as drugs and alcohol have ruined the lives of people all over the world. Read about current views and ideas on addiction.

By Josh Clark & Sascha Bos

Antidepressants are the first line of treatment for depression. Sales of antidepressants total $50 billion annually, making this class of drugs one of the leading prescription medications. But are they effective?

By Craig Freudenrich, Ph.D.

Alien hand syndrome sounds like something from a B-grade horror movie, but it's a real condition. You could be completely at the mercy of your own renegade hand -- it could keep your other hand from functioning, punch you or even choke you.

By Charles W. Bryant

Your co-worker just yawned in a meeting, and now everyone on his side of the table is yawning, too. Learn about what might've caused him to do it in the first place and why you're likely to yawn right along with them.

By Melanie Radzicki McManus

Alcoholism can be difficult to spot. Learn the difference between heavy drinking and alcoholism, how alcohol affects the body, what factors may lead to alcoholism and what treatments are available for this addiction.

By Stephanie Watson

Dreams combine verbal, visual and emotional stimuli into mystifying storylines. Should we bother to interpret them? Are they random brain impulses, or do they offer insight into our waking lives?

By Lee Ann Obringer & Yves Jeffcoat

Whether brain death is a result of cardiac arrest and lack of oxygen to the brain, or of a gunshot wound to the head, the diagnosis is the same. Learn what the term "brain dead" actually means.

By Leslie C. Olson

It doesn't exactly seem like something the human body would do, let a large portion of itself go to complete waste. Is it true that most of your brain is on permanent hiatus?

By Patrick J. Kiger & Austin Henderson

Three weeks of hard work. Is that all it takes to kick your smoking habit, taste for junk food or serial inability to stop hitting the snooze button? Sounds almost too good to be true, doesn't it?

By Julia Layton

Once scientists discovered that some members of the great ape family could recognize their reflections in mirrors, academics began to wonder whether these animals were actually conscious of themselves. That debate continues today.

By Jessika Toothman & Sascha Bos

We'd like to think we're pretty clever, but when you correct for body mass, dolphin brains aren't far off from our own. What cognitive skills do dolphins possess, and could they really be our intellectual equals?

By Jessika Toothman

Computers can handle far more calculations per second than the human brain, and can store and retrieve information very reliably. Should we be jealous of these hunks of silicon and metal on our desks?

By Jonathan Strickland

You've just touched a hot stove -- and probably felt an immediate sharp pain, then a dull ache. How do we sense pain, and why does it eventually go away?

By Craig Freudenrich, Ph.D.

That man dressed in animal skins and running around Jerusalem trying to baptize people isn't alone. Tourists in Jerusalem sometimes suffer from a strange conviction that they are Biblical figures. Are they mentally ill or is there more to it?

By Katie Lambert

You might think that not being able to feel pain would be a blessing. No tears, no painkillers, no lingering aches. But really, not being able to feel pain is dangerous.

By Katie Lambert

Collective hysteria can spread when a fear exists of exposure to a disease, combined with a contained environment. Learn more about collective hysteria works.

By Jacob Silverman & Austin Henderson

Religion is one of the three things you're never supposed to talk about if you don't want your dinner party to turn into a food fight. But what about looking at religion through the lens of science instead of faith? Is there a connection between our gray matters and pray matters?

By Molly Edmonds

Sleepwalking is an intriguing phenomenon. How can a person be unconscious but still coordinate his or her limbs? And how do we know when we're really awake?

By Katie Lambert

In the past, applying electricity to the brain was a painful measure of last resort. Now with lower power and electrodes surgically planted deep within the brain, it could be the answer to many debilitating diseases.

By Isaac Perry Clements

If you could control your dreams, what would you do? Grow wings and fly, travel to ancient Rome, dine with Marilyn Monroe, open opera season at the Met? It could be possible.

By Katie Lambert & Sascha Bos