Agent Plus Environment

Genes: predictor of academic ability?

I found an article today about British researchers who are analyzing the DNA of 4000+ schoolchildren with the goal of finding a relation between the kids’ genes and their academic abilities.

The reason I bring this up is not because the researchers found a gene to explain why you failed your math test, but because the article falls heavily into the “nature vs. nurture” trap. For those of you unfamiliar, nature vs. nurture is the debate over the relative importance of innate qualities built-in from the chromosomes (“nature”), versus personal experiences, environment, and upbringing (“nurture”) in determining individual physical and behavioral differences. Really, it shouldn’t be a debate: organisms’ traits are a result of the interaction of what they start with and where they grow up: nature and nurture. The context in which any organism develops is remarkably important in determining which genes are expressed and how they interact to produce behavior.

Back to the article. There’s one paragraph in particular that gets me:

“Research into height, for example, has picked out 300 genes that affect how tall people will grow, but even these genes can only explain 15% of the total variations in human height. It implies that hundreds more genes must also play a part.”

No, that’s a false choice. What’s implied is that there could be other genes involved, but – and here’s a novel thought – maybe the environment (e.g., nutrition) plays a role? A little bitsy part? Maybe?

A little googling:

In hopes that it was just the reporters who were being deterministic, not the researchers themselves, I set out to find more information.

Robert Plomin of King’s College, London, is the behavioral geneticist cited in the article. He’s currently performing a huge study of British twins. I’ve found several articles stating that he’s a “pioneer in bringing nature and nurture together,” and instead of calling it a “nature vs. nurture” debate, he’s said to have call it (much more appropriately) “nature and nurture.” That’s reassuring. I’d have to read a few of his papers to be certain, but my interim conclusion is that it’s just the reporters.

If you’re interested, I also recently came across a popular article on the gender myth and genetic differences in men and women. It happens to cite Robert Plomin, too.

I collected up all the articles, blog posts, and cool videos about my LARSS summer into one nice, neat page. There’s new material there – I’ve included our project abstract as well as videos of flying quadcopters!

Check it out.

You know you want to.

On the last day of my LARSS internship, NASA EDGE filmed my lab for their Future of Aeronautics episode! It’s currently up on NASA’s main page in the “Podcasts and Vodcasts” section, and it’s available both online and through iTunes. The opening montage has clips of my labmates and I, and the segment about our work starts at 19:18 and lasts three minutes. If you want to see just our segment, it’s on youtube.

I encourage you to take a look!

Not your everyday summer job

This summer, I’ve been working for NASA as an intern in the Langley Aerospace Research Summer Scholars Program. In a one-sentence summary, I’m working with a systems engineering team to develop and integrate the software and hardware needed for both indoor and outdoor tests of autonomous, unmanned multi-vehicle flight control.

But what does that mean, in terms of what I actually do?

It means the past seven weeks have been spent laboring over keyboards, switching between C, C++, Java, and Processing. I’ve carried my lab’s miniature Parking Lot Exploration Rover outside in 105ºF weather to test a navigation algorithm. I’ve learned about PID controls, GPS sensors, and radio communication. I’ve evaluated ground control station software, delved into the depths of an open source flight simulator, and discovered how tricky network protocols can be. I’ve written software for 3D data display programs, data parsers, and communication links. I’ve learned that when you’re one of a team of ten interns, all tackling pieces of the same large project, communication is crucial.

I’m enjoying this internship immensely. Vassar News just released an ego-boosting article about me and my summer, which I suggest you check out.

You’ll be hearing more from me on this subject. Stay tuned.

Emotional intensity and the individual

Let’s say you’re at home. Maybe you’re lounging indolently on the couch, feet up on the brown wood coffee table, television whining at you from across the room. Maybe you’re cooking tonight’s dinner, chopping vegetables with careful strokes, sliding the ever growing pile of peppers and onions and tomatoes into a hissing frying pan. Maybe not. Maybe you’re in another room when the fire alarm sounds, bleep bleep bleep, blaring its cacophonous melody into your generally peaceful home.

How do you react?

Do you scream? Do you calmly turn off the stove, flap a towel at the cloudy air around the smoke detector, and wait patiently for it to detect that there’s not actually a fire? Do you leap up from the couch, tripping over the coffee table in your panic, terrified of burning to death in your own living room?

The strength of your emotional response to this (or any) emotional stimulus is known as emotional intensity. Emotional intensity can be measured with psychological scales, such as the aptly-named Emotional Intensity Scale (EIS) developed by Bachorowski & Braaten (1994) [PDF]. The underlying if obvious assumptions of these scales are that some individuals experience all of their emotions more intensely than other individuals, and all individuals may respond with different strengths to the same stimuli.

Your personality influences your experience of emotions

You may already be familiar with the Big 5 personality factors: Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism (sometimes called Emotional Stability). (If not, look them up.) Robert McFatter, in his 1998 paper Emotional Intensity: Some components and their relations to extraversion and neuroticism [PDF], investigated the relation between temperament and the intensity of positive and negative emotions. (Positive emotions included happiness and pleasure; negative emotions included worry, guilt, anger, and sadness.) McFatter described and tested several models, all of which had slightly different predictions about how neuroticism, extraversion, and positive and negative emotional intensity are correlated.

1. Larsen & Ketelaar model: The measures used to examine emotional intensity in this model tapped frequency of experienced emotions more than the intensity of single (and possibly infrequent) reactions. The model predicts that Extraversion is positively related to positive intensity and unrelated to negative intensity, and that Neuroticism is unrelated to positive intensity and positively related to negative intensity.
2. Larsen & Diener model: This model draws on the theory that the intensity of experienced emotions is used to regulate arousal levels. Arousal level can be tied to Extraversion, so this model predicts that Extraversion is positively related to both positive and negative intensity. Larsen & Diener also predict that Neuroticism is similarly positively correlated with positive and negative intensity.
3. Wallace, Bachorowski, & Newman (WBN) model: Extraversion is suggested to reflect a behavioral approach system and a behavioral inhibition system. Neuroticism is suggested to reflect the reactivity of an arousal system responding to the behavioral approach/inhibition systems that serves to prepare the individual to respond. This model accordingly predicts that Extraversion is positively related to positive intensity and negative related to negative intensity (and thus that Extraversion is overall uncorrelated with overall emotional intensity), and that Neuroticism is positively related to both positive and negative intensity.
4. Gray’s model: This model predicts that the behavioral approach/inhibition systems form dimensions that are rotated roughly thirty degrees from the Extroversion and Neuroticism dimensions, so they don’t line up. The model predicts that Extraversion is positively related to positive intensity but only weakly negatively related to negative intensity. Similarly, Neuroticism is predicted to be weakly positively related to positive intensity, and positively related to negative intensity. Gray’s model, furthermore, suggests that the negative emotions can be subdivided into anger/panic and anxiety/fear categories. These subcategories may have different relations to Extraversion.

Methods, Correlations, Analyses, Results

To test these models, McFatter gave a series of questionnaires to 1553 college students taking introductory psychology classes (596 male). Participants completed the 30-item EIS to examine positive and negative emotional intensity (14 items and 16 items, respectively), the Eysenck Personality Inventory (EPI) for measuring Extraversion and Neuroticism (in addition to subscales for impulsivity and sociability), and a third unrelated questionnaire.

Based on an initial factor analysis of the EIS, negative intensity was separated into two groups: anger/frustration (hereafter referred to as “anger intensity”) and non-anger, such as worry, guilt, and sadness (referred to as “non-anger intensity”). This result supports Gray’s theory that two separate negative emotion systems exist.

Consistent with both Gray’s model and the WBN model, Extraversion was shown to be positively related to positive emotional intensity (r=0.19, P<0.0001), negatively related to non-anger emotional intensity (r=0.18, p<0.0001), and unrelated to anger intensity (r=0.02). In plainer terms, individuals with high Extroversion scores tended to experience more intense positive emotions and less intense negative emotions.

Neuroticism, on the other hand, was shown to be positively related to all three kinds of emotional intensity, though less strongly to positive intensity (r=0.18, p<0.0001) than to non-anger or anger intensity (r=0.56,p<0.0001 and r=0.45,p<0.0001, respectively). That is to say, individuals with high Neuroticism scores tended to report experiencing more intense emotions overall. This is consistent with Gray's model.

A couple other interesting results:

Females reported significantly higher emotional intensity than males overall, with the largest difference seen in negative intensity (0.411, p<0.0001).

The positive relation between Extraversion and emotional intensity was stronger among people with a high Neuroticism score.

Neuroticism and emotional intensity

It’s hard to tell without reading a pile of psychology papers, but the fact that Neuroticism was positively related to positive emotional intensity was surprising. Previous results found a negative relation, though several of these had measured emotional intensity with a different scale–one that seemed to confound frequency and intensity of the experienced emotions. The WBN model, relatedly, claimed that Neuroticism reflected general emotional reactivity. (Recall the personality factor’s other name: Emotional Stability.) So McFatter investigated.

He found that when looking at the difference of the positive intensity and negative intensity scores, the relative emotional intensity was negatively related to Neuroticism, as in those previous studies. However, when examined on their own with the other variables controlled, the relations of both positive and negative intensity to Neuroticism were positive. The WBN model only explained a portion of the story.

McFatter’s results, overall, support Gray’s model and the WBN model, suggesting that the variations in positive and negative emotional intensity may be the result of separate emotion systems, but that they do have some common variation that may best be explained by their relations to Neuroticism.

References:
McFatter, R. (1998). Emotional Intensity: Some components and their relations to extraversion and neuroticism. Person. individ. Diff., 24(6): 747-758. [PDF]

The longest Monday of my life

I recently returned to the US from Australia. The 14-hour flight took me from Monday morning in Sydney to Monday morning, again, in L.A. Crossing the date line messed up my sense of time enough without the added bonus of thinking I should be heading to bed just as the sun began to climb into the California sky.

You may be familiar with the concept: Jet lag. The catch-all name for circadian misalignment, the disruption of sleep cycles and circadian rhythms. If you’ve had the pleasure of crossing time zones in a jet plane, whether it was a mere three-hour hop from one coast of the US to the other or a trip to another continent, chances are, you’ve experienced some amount of jet lag.

The pathophysiology of jet lag

Normally, two systems–the homeostatic system and the circadian system–work together to produce a 24-hour sleep cycle. During the day, the homeostatic system slowly accumulates a ‘sleep drive,’ a desire to sleep that increases as a function of time spent awake. The circadian system generates an alerting signal in opposition to this sleep drive, which, during the day, keeps a person from feeling increasingly sleepy. An hour or two before bedtime, this signal subsides, and s/he realizes it’s time to hit the pillow. The sleep drive dissipates as a person sleeps and by morning (assuming a full night’s rest and possibly some coffee), s/he will be feeling alert and ready to go again.

Robert Sack wrote a delightful paper [PDF] on jet lag, by the way, which is where I’m getting much of my information.

So we’ve got a nice cycle of sleep. Jet lag is what happens when the homeostatic and circadian processes are misaligned. For example, the circadian system may signal a person to be alert when it’s not actually morning, or may be reduced during daytime hours, causing daytime sleepiness because the homeostatic sleep drive is no longer canceled out.

But I don’t want to be sleepy!

How do you beat jet lag? Robert Sack lists three primary approaches:

1. Reset the body clock
2. Prescribed sleep scheduling
3. Medication to counteract daytime sleepiness or insomnia

Let’s start with the first one, as it turns out to be the most complicated.

Resetting the body clock

The two most effective ways to reset the body clock are 1) through bright light exposure, and 2) timed melatonin administration. (But see below; fasting can also reset the body clock.)

Light is one of the most important cues about time of day and has the greatest effect on circadian timing (much smaller effects are seen from regular activities and meals, for example). Studies have shown that without light cues, totally blind people tend to have free-running circadian rhythms with an average period of 24.5 hours, instead of the usual 24. If a person is exposed to bright light early in the day, the person’s internal clock is reset to an earlier time; if exposure is instead in the evening, the internal clock is reset to a later time. Brighter light has more of an effect (such as the sun, at 3000 to 10,000 lux), though lower intensities (e.g., 100-550 lux) can produce changes.

Artificial light sources can be used to supplement daylight, to help reset a person’s internal clock to the correct new time zone when traveling. Alternatively, a person could wear very dark glasses, as light avoidance could help minimize the problems of light exposure at the wrong time of day or night.

Resetting the body clock, Part 2: Melatonin

Melatonin is a hormone that has been linked to the regulation of circadian rhythms and sleep cycles [PDF]. Melatonin is secreted by the pineal gland at night; secretion is suppressed by light exposure, and as such, the hormone can be thought of as a “darkness signal.” If doses of melatonin are administered in the morning, circadian rhythms will be shifted later; evening doses shift rhythms earlier. Timing of the doses is more important than amount per dose, though it remains to be seen what the optimal dose and optimal time of administration is–trials have been done with doses from 0.5 to 10mg, at times ranging from three days before departure to five days after arrival in the new time zone.

If doses of melatonin are combined with light exposure, the results are what you might expect: synergistic if both are administered to produce a time shift in the same direction (both earlier or both later); antagonistic otherwise.

Sleep, wake, sleep, wake

The second way to beat jet lag: Sleep at weird times. Slowly adjust your sleep schedule to match that of your destination, or keep your home sleep schedule for a while after you arrive. The problem with this is that your sleep-wake schedule won’t match up with that of the people around you, and if you need to be awake for breakfast at 7am or for a meeting in the afternoon, your sleep schedule may interfere. Use this method at your own risk.

Drugs for everything

Lastly, we have sleep medicines. As you might guess, hypnotic medications combat insomnia and stimulants fight off daytime sleepiness pretty well, because by definition, that’s what they do. Both benzodiazepine and non-benzodiazepine drugs have been shown to be effective in the first case; for the latter, the most common solution is to consume more coffee [PDF]. This works! In the study linked, subjects were treated with slow-release caffeine or with melatonin prior to a long eastward flight; the caffeine subjects were less sleepy than either melatonin or placebo. Granted, caffeine subjects also took longer to fall asleep later and awoke more frequently, but that may be a risk you have to take.

Lagging behind

Light, melatonin, drugs, strange sleep schedules. Of course, the only solution that will always work is time. The homeostatic and circadian processes need to realign, and while the aforementioned ways of beating jet lag can fast track the process, it still takes time.

UPDATE: I was alerted by a friend of the existence of further research of which I was unaware: Another way to reset your sleep-wake cycle is to stop eating. If you fast for about 12 to 16 hours, your body clock will reset, with whatever time you break your fast as morning. The Fuller, Lu, & Saper paper [PDF], published in Science, discusses the mechanism, though a more recent paper argues that the Fuller et al. results are inconclusive.

Beautiful and good to eat

Deep down, maybe we all know we are, every one of us, a unique snowflake. But a lot of people, they don’t want it to be true. They want all the snowflakes to melt together into one big puddle. They want to be able to share their subjective view of the world with everyone else. They want to be able to look at a sunset and know that what it’s like for me to see the sunset is the same as what it’s like for you to see the sunset.

Hey, we all want things we can’t have. And in this case, science says no! Here’s a piece of wisdom from David Brin’s sci-fi novel Kiln People:

“We may use similar terms to describe a sunset. Our subjective worlds often correspond, correlate, and map onto each other. That makes cooperation and relationships possible, even complex civilization. Yet a person’s actual sensations and feelings remain forever unique. Because a brain isn’t a computer and neurons aren’t transistors.

It’s why telepathy can’t happen. We are, each of us, singular and forever alien…”

The amazing thing about people is that this fact doesn’t deter us. We keep trying to share our sensations and feelings with each other. As Virginia Woolf writes in her book Orlando:

For it is a curious fact that though human beings have such imperfect means of communication, that they can only say “good to eat” when they mean “beautiful” and the other way about, they will yet endure ridicule and misunderstanding rather than keep any experience to themselves.

To be known and understood

Maybe we’re just stubborn. Maybe we’re clinging to a shred of hope that science is wrong and someday, instead of just overlapping with pieces of each other, we’ll be able to know what it’s like to experience the sunset the way someone else does. Here’s a passage from a favorite book of mine, Man Walks Into a Room by Nicole Krauss:

“When you’re young, you think it’s going to be solved by love. But it never is. Being close—as close as you can get—to another person only makes clear the impassable distance between you. . . .

“But see, the incredible thing about people is that we forgot,” Ray continued. “Time passes and somehow the hope creeps back and sooner or later someone else comes along and we think this is the one. And the whole thing starts all over again. We got through our lives like that, and either we just accept the lesser relationship—it may not be total understanding, but it’s pretty good—or we keep trying for that perfect union, trying and failing, leaving behind us a trail of broken hearts, our own included. In the end, we die as alone as we were born, having struggled to understand others, to make ourselves understood, but having failed in what we once imagined was possible.”

“People really want that, what did you say, merging souls? Total union?” [Samson]

“Yes. Or at least they think they do. Mostly what they want, I think, is to feel known.”

What do you think? Is the ultimate human goal to feel known and understood? And if that’s the case, is the illusion of feeling known enough to compensate for never truly being able to share one’s experiences with anyone else?