About a decade ago, some early scientific research suggested that playing memory games could increase "fluid intelligence," which is the capacity to solve problems in novel situations, independent of acquired knowledge.

A spate of apps, books, and classes resulted, all claiming to make people smarter. Unfortunately, later studies proved that "braintraining" (as it's sometimes called) has no effect on your general intelligence.

The most recent research in psychology and neuroscience, however, has found five effective strategies for improving your intelligence. Some of them may surprise you.

1. Believe that it's possible.

According to a study cited by The New York Times, a group of students were given classes on how the brain works. Half were told that it's possible to get smarter; the other were told the opposite.

When tested on the course materials, the first group retained 85 percent of what they'd heard while the second group retained only 54 percent. In other words, simply believing that you can make yourself smarter actually makes you smarter!

Apparently your brain takes cues from your beliefs and becomes more "cooperative," thereby making it easier for neurons to build connections. Or, as Henry Ford once said: "if you think you can do a thing or think you can't do a thing, you're right."

BTW, if this column reinforces your belief that it's possible to take action to become smarter, the act of reading this article isn't just conveying information; it's actively making your brain more effective!

2. Socialize more frequently.

Social interaction, such as talking with friends and family, may also increase your intelligence.

For example, a study conducted from 1998 to 2004 showed that people who had more social interaction scored higher on memory retention tests given at two-year intervals.

Interestingly, the content of the social interaction doesn't seem to be that important. The effect was greater for people who lacked a college degree, who presumably weren't discussing existentialism or rocket science.

The brain benefit of being social makes sense when you consider that the human brain evolved to perform optimally inside the context of a "tribe."

3. Exercise more regularly.

The advice "get plenty of exercise" is usually presented as a way to avoid stress-related illnesses.

However, according to the latest neuroscience, exercise increases the level of brain-derived neurotrophic factor (BDNF), a protein that occurs in your blood and brain that "promotes the growth and formation of new neurons."

Since that's how the brain creates and reinforces memories, exercise is literally making you smarter. Indeed, exercise creates a measurable increase in the hippocampus region of the human brain.

Experience in the workplace bears this out. There's a reason that so many CEOs and successful people start their day with exercise--they may not know it, but the habit is actually making them smarter and more competitive.

4. Drink more coffee or tea.

Multiple research studies show that stimulants have the positive effect of increasing your focus by releasing dopamine into the most important parts of your brain, increasing your long-term memory.

While there are prescription drugs that do this, the easiest way to block dopamine is to ingest a hefty dose of good old caffeine.

Caffeine also blocks the effects of adenosine, a protein that slows the brain down so that you can go to sleep. Less adenosine means that your neurons fire more often, making you smarter.

Finally, caffeine releases norepinephrine, which increases your reaction, memory retention, and the performance of your brain in general.

5. Daydream more often.

Contrary to popular belief, letting your mind wander isn't mental laziness; it's the exact opposite. When you're daydreaming, your mind is crazy active.

Daydreaming stimulates imagination and creativity by allowing otherwise disconnected parts of your brain to wire themselves together with new neural pathways.

Research has shown that students who daydream on average do better on standardized tests than students who remain over-focused on the task at hand.

Daydreaming is also the first step in mindfulness training, the technique which Steve Jobs used to become more creative.