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If I were to pick my all-time favorite character from movies and TV, I'd pick Leonard Nimoy as Mr. Spock. Admittedly, I'm a Star Trek addict, so the choice is biased, but as a science student growing up, I was fascinated with Mr. Spock's unwavering (but charmingly flawed) insistence on logic, logic, and nothing but logic. His thinking mirrored that of another TV favorite, Sergeant Joe Friday (played by Jack Webb) of Dragnet, who always requested (and seldom received), "Just the facts, ma'am."
While I admired my fictional heroes' adherence to data and objectivity, I wondered how they could achieve pure rationality. How could they, or any of us for that matter, know what's logical?
We tend to think of rational decision-making in a Mr. Spock kind of way. Shouldn't we, like Spock, cast off the shackles of emotion? Couldn't we make better decisions if unhindered by the feelings that cloud our minds and muddy our judgment?
The answer is probably no. Neuroscience isn't bearing out the Spockian notion that rationality and emotionality are mutually exclusive. In fact, just the opposite may be true. We need our emotions to tell us what's logical.
In a research report published September 14 in the Proceedings of the National Academy of Sciences, researchers at Indiana University offer evidence that the amygdala of the brain, which plays a big part in both memory and emotion, helps you, me, and Joe Friday (perhaps even the green-blooded Spock) differentiate relevant from irrelevant information.
Thirty right-handed subjects (20-34 years old) participated in the Indiana project. During training, they studied pictures of three faces and learned names for the faces: Andy, Bill, and Chad. They also viewed pictures of houses and buildings. As part of the training, the participants experienced a tiny electric shock on the finger when certain house or building pictures appeared. The shock conditioned the subjects to be just a little bit afraid of those particular pictures. The shock made those pictures, but not others, "affectively significant."
Later, while inside the fMRI (functional magnetic resonance imaging) brain scanner, the participants saw one of the faces followed by various distracters along with a house picture, a building picture, or no picture at all. Their brains were scanned while they identified the face and then indicated whether they saw a house, a building, or no structure.
The researchers measured what's called the "attentional blink." Normally, the shorter the time period between the first and second target (the face and then a house or building), the less likely a person is to see the second target. But in this study as in several others, the attentional blink was reduced when affectively significant pictures appeared. The participants were more likely to spot the second target after a very short lag time when they'd previously learned to fear it.
The fMRI scans revealed that the subjects' brains reacted more strongly to the affectively significant pictures, both in the brain's visual processing areas and in the amygdala, where a lot of emotion and memory processing occurs. The greater brain activity predicted the reduced attentional blink, suggesting that emotional significance enhances visual performance.
The key lies in that amygdala. Signals that originate in the amygdala modify the action of the brain's visual processing regions. The process probably occurs through two pathways: one running directly from the amygdala to the brain's visual centers and the other running indirectly through the brain's frontoparietal regions, which control the "pay attention" response.
Thus, say the researchers, "The amygdala helps separate the significant from the mundane." From that I have to conclude that Spock must have had a human-style, emotion-drenched amygdala helping him separate the important from the irrelevant. How else could he have behaved so logically?
For details, see
Seung-Lark Lim, Srikanth Padmala, and Luiz Pesso, "Segregating the Significant from the Mundane on a Moment-to-Moment Basis via Direct and Indirect Amygdala Contributions," Proceedings of the National Academy of Sciences, published online ahead of print September 14, 2009.
