Tag: addiction

the New York Times blows it big time on brain imaging

The New York Times has a terrible, terrible Op-Ed piece today by Martin Lindstrom (who I’m not going to link to, because I don’t want to throw any more bones his way). If you believe Lindstrom, you don’t just like your iPhone a lot; you love it. Literally. And the reason you love it, shockingly, is your brain:

Earlier this year, I carried out an fMRI experiment to find out whether iPhones were really, truly addictive, no less so than alcohol, cocaine, shopping or video games. In conjunction with the San Diego-based firm MindSign Neuromarketing, I enlisted eight men and eight women between the ages of 18 and 25. Our 16 subjects were exposed separately to audio and to video of a ringing and vibrating iPhone.

…

But most striking of all was the flurry of activation in the insular cortex of the brain, which is associated with feelings of love and compassion. The subjects’ brains responded to the sound of their phones as they would respond to the presence or proximity of a girlfriend, boyfriend or family member.

In short, the subjects didn’t demonstrate the classic brain-based signs of addiction. Instead, they loved their iPhones.

There’s so much wrong with just these three short paragraphs (to say nothing of the rest of the article, which features plenty of other whoppers) that it’s hard to know where to begin. But let’s try. Take first the central premise–that an fMRI experiment could help determine whether iPhones are no less addictive than alcohol or cocaine. The tacit assumption here is that all the behavioral evidence you could muster–say, from people’s reports about how they use their iPhones, or clinicians’ observations about how iPhones affect their users–isn’t sufficient to make that determination; to “really, truly” know if something’s addictive, you need to look at what the brain is doing when people think about their iPhones. This idea is absurd inasmuch as addiction is defined on the basis of its behavioral consequences, not (right now, anyway) by the presence or absence of some biomarker. What makes someone an alcoholic is the fact that they’re dependent on alcohol, have trouble going without it, find that their alcohol use interferes with multiple aspects of their day-to-day life, and generally suffer functional impairment because of it–not the fact that their brain lights up when they look at pictures of Johnny Walker red. If someone couldn’t stop drinking–to the point where they lost their job, family, and friends–but their brain failed to display a putative biomarker for addiction, it would be strange indeed to say “well, you show all the signs, but I guess you’re not really addicted to alcohol after all.”

Now, there may come a day (and it will be a great one) when we have biomarkers sufficiently accurate that they can stand in for the much more tedious process of diagnosing someone’s addiction the conventional way. But that day is, to put it gently, a long way off. Right now, if you want to know if iPhones are addictive, the best way to do that is to, well, spend some time observing and interviewing iPhone users (and some quantitative analysis would be helpful).

Of course, it’s not clear what Lindstrom thinks an appropriate biomarker for addiction would be in any case. Presumably it would have something to do with the reward system; but what? Suppose Lindstrom had seen robust activation in the ventral striatum–a critical component of the brain’s reward system–when participants gazed upon the iPhone: what then? Would this have implied people are addicted to iPhones? But people also show striatal activity when gazing on food, money, beautiful faces, and any number of other stimuli. Does that mean the average person is addicted to all of the above? A marker of pleasure or reward, maybe (though even that’s not certain), but addiction? How could a single fMRI experiment with 16 subjects viewing pictures of iPhones confirm or disconfirm the presence of addiction? Lindstrom doesn’t say. I suppose he has good reason not to say: if he really did have access to an accurate fMRI-based biomarker for addiction, he’d be in a position to make millions (billions?) off the technology. To date, no one else has come close to identifying a clinically accurate fMRI biomarker for any kind of addiction (for more technical readers, I’m talking here about cross-validated methods that have both sensitivity and specificity comparable to traditional approaches when applied to new subjects–not individual studies that claim 90% with-sample classification accuracy based on simple regression models). So we should, to put it mildly, be very skeptical that Lindstrom’s study was ever in a position to do what he says it was designed to do.

We should also ask all sorts of salient and important questions about who the people are who are supposedly in love with their iPhones. Who’s the “You” in the “You Love Your iPhone” of the title? We don’t know, because we don’t know who the participants in Lindstrom’s sample, were, aside from the fact that they were eight men and eight women aged 18 to 25. But we’d like to know some other important things. For instance, were they selected for specific characteristics? Were they, say, already avid iPhone users? Did they report loving, or being addicted to their iPhones? If so, would it surprise us that people chosen for their close attachment to their iPhones also showed brain activity patterns typical of close attachment? (Which, incidentally, they actually don’t–but more on that below.) And if not, are we to believe that the average person pulled off the street–who probably has limited experience with iPhones–really responds to the sound of their phones “as they would respond to the presence or proximity of a girlfriend, boyfriend or family member”? Is the takeaway message of Lindstrom’s Op-Ed that iPhones are actually people, as far as our brains are concerned?

In fairness, space in the Times is limited, so maybe it’s not fair to demand this level of detail in the Op-Ed iteslf. But the bigger problem is that we have no way of evaluating Lindstrom’s claims, period, because (as far as I can tell), his study hasn’t been published or peer-reviewed anywhere. Presumably, it’s proprietary information that belongs to the neuromarketing firm in question. Which is to say, the NYT is basically giving Lindstrom license to talk freely about scientific-sounding findings that can’t actually be independently confirmed, disputed, or critiqued by members of the scientific community with expertise in the very methods Lindstrom is applying (expertise which, one might add, he himself lacks). For all we know, he could have made everything up. To be clear, I don’t really think he did make everything up–but surely, somewhere in the editorial process someone at the NYT should have stepped in and said, “hey, these are pretty strong scientific claims; is there any way we can make your results–on which your whole article hangs–available for other experts to examine?”

This brings us to what might be the biggest whopper of all, and the real driver of the article title: the claim that “most striking of all was the flurry of activation in the insular cortex of the brain, which is associated with feelings of love and compassion“. Russ Poldrack already tore this statement to shreds earlier this morning:

Insular cortex may well be associated with feelings of love and compassion, but this hardly proves that we are in love with our iPhones.  In Tal Yarkoni’s recent paper in Nature Methods, we found that the anterior insula was one of the most highly activated part of the brain, showing activation in nearly 1/3 of all imaging studies!  Further, the well-known studies of love by Helen Fisher and colleagues don’t even show activation in the insula related to love, but instead in classic reward system areas.  So far as I can tell, this particular reverse inference was simply fabricated from whole cloth.  I would have hoped that the NY Times would have learned its lesson from the last episode.

But you don’t have to take Russ’s word for it; if you surf for a few terms on our Neurosynth website, making sure to select “forward inference” under image type, you’ll notice that the insula shows up for almost everything. That’s not an accident; it’s because the insula (or at least the anterior part of the insula) plays a very broad role in goal-directed cognition. It really is activated when you’re doing almost anything that involves, say, following instructions an experimenter gave you, or attending to external stimuli, or mulling over something salient in the environment. You can see this pretty clearly in this modified figure from our Nature Methods paper (I’ve circled the right insula):

Proportion of studies reporting activation at each voxel

The insula is one of a few ‘hotspots’ where activation is reported very frequently in neuroimaging articles (the other major one being the dorsal medial frontal cortex). So, by definition, there can’t be all that much specificity to what the insula is doing, since it pops up so often. To put it differently, as Russ and others have repeatedly pointed out, the fact that a given region activates when people are in a particular psychological state (e.g., love) doesn’t give you license to conclude that that state is present just because you see activity in the region in question. If language, working memory, physical pain, anger, visual perception, motor sequencing, and memory retrieval all activate the insula, then knowing that the insula is active is of very little diagnostic value. That’s not to say that some psychological states might not be more strongly associated with insula activity (again, you can see this on Neurosynth if you switch the image type to ‘reverse inference’ and browse around); it’s just that, probabilistically speaking, the mere fact that the insula is active gives you very little basis for saying anything concrete about what people are experiencing.

In fact, to account for Lindstrom’s findings, you don’t have to appeal to love or addiction at all. There’s a much simpler way to explain why seeing or hearing an iPhone might elicit insula activation. For most people, the onset of visual or auditory stimulation is a salient event that causes redirection of attention to the stimulated channel. I’d be pretty surprised, actually, if you could present any picture or sound to participants in an fMRI scanner and not elicit robust insula activity. Orienting and sustaining attention to salient things seems to be a big part of what the anterior insula is doing (whether or not that’s ultimately its ‘core’ function). So the most appropriate conclusion to draw from the fact that viewing iPhone pictures produces increased insula activity is something vague like “people are paying more attention to iPhones”, or “iPhones are particularly salient and interesting objects to humans living in 2011.” Not something like “no, really, you love your iPhone!”

In sum, the NYT screwed up. Lindstrom appears to have a habit of making overblown claims about neuroimaging evidence, so it’s not surprising he would write this type of piece; but the NYT editorial staff is supposedly there to filter out precisely this kind of pseudoscientific advertorial. And they screwed up. It’s a particularly big screw-up given that (a) as of right now, Lindstrom’s Op-Ed is the single most emailed article on the NYT site, and (b) this incident almost perfectly recapitulates another NYT article 4 years ago in which some neuroscientists and neuromarketers wrote a grossly overblown Op-Ed claiming to be able to infer, in detail, people’s opinions about presidential candidates. That time, Russ Poldrack and a bunch of other big names in cognitive neuroscience wrote a concise rebuttal that appeared in the NYT (but unfortunately, isn’t linked to from the original Op-Ed, so anyone who stumbles across the original now has no way of knowing how ridiculous it is). One hopes the NYT follows up in similar fashion this time around. They certainly owe it to their readers–some of whom, if you believe Lindstrom, are now in danger of dumping their current partners for their iPhones.

h/t: Molly Crockett

internet use causes depression! or not.

I have a policy of not saying negative things about people (or places, or things) on this blog, and I think I’ve generally been pretty good about adhering to that policy. But I also think it’s important for scientists to speak up in cases where journalists or other scientists misrepresent scientific research in a way that could have a potentially large impact on people’s behavior, and this is one of those cases. All day long, media outlets have been full of reports about a new study that purportedly reveals that the internet–that most faithful of friends, always just a click away with its soothing, warm embrace–has a dark side: using it makes you depressed!

In fairness, most of the stories have been careful to note that the  study only “links” heavy internet use to depression, without necessarily implying that internet use causes depression. And the authors acknowledge that point themselves:

“While many of us use the Internet to pay bills, shop and send emails, there is a small subset of the population who find it hard to control how much time they spend online, to the point where it interferes with their daily activities,” said researcher Dr. Catriona Morrison, of the University of Leeds, in a statement. “Our research indicates that excessive Internet use is associated with depression, but what we don’t know is which comes first. Are depressed people drawn to the Internet or does the Internet cause depression?”

So you might think all’s well in the world of science and science journalism. But in other places, the study’s authors weren’t nearly so circumspect. For example, the authors suggest that 1.2% of the population can be considered addicted to the internet–a rate they claim is double that of compulsive gambling; and they suggest that their results “feed the public speculation that overengagement in websites that serve/replace a social function might be linked to maladaptive psychological functioning,” and “add weight to the recent suggestion that IA should be taken seriously as a distinct psychiatric construct.”

These are pretty strong claims; if the study’s findings are to be believed, we should at least be seriously considering the possibility that using the internet is making some of us depressed. At worst, we should be diagnosing people with internet addiction and doing… well, presumably something to treat them.

The trouble is that it’s not at all clear that the study’s findings should be believed. Or at least, it’s not clear that they really support any of the statements made above.

Let’s start with what the study (note: restricted access) actually shows. The authors, Catriona Morrison and Helen Gore (M&G), surveyed 1,319 subjects via UK-based social networking sites. They had participants fill out 3 self-report measures: the Internet Addiction Test (IAT), which measures dissatisfaction with one’s internet usage; the Internet Function Questionnaire, which asks respondents to indicate the relative proportion of time they spend on different internet activities (e.g., e-mail, social networking, porn, etc.); and the Beck Depression Inventory (BDI), a very widely-used measure of depression.

M&G identify a number of findings, three of which appear to support most of their conclusions. First, they report a very strong positive correlation (r = .49) between internet addiction and depression scores; second, they identify a small group of 18 subjects (1.2%) who they argue qualify as internet addicts (IA group) based on their scores on the IAT; and third, they suggest that people who used the internet more heavily “spent proportionately more time on online gaming sites, sexually gratifying websites, browsing, online communities and chat sites.”

These findings may sound compelling, but there are a number of methodological shortcomings of the study that make them very difficult to interpret in any meaningful way. As far as I can tell, none of these concerns are addressed in the paper:

First, participants were recruited online, via social networking sites. This introduces a huge selection bias: you can’t expect to obtain accurate estimates of how much, and how adaptively, people use the internet by sampling only from the population of internet users! It’s the equivalent of trying to establish cell phone usage patterns by randomly dialing only land-line numbers. Not a very good idea. And note that, not only could the study not reach people who don’t use the internet, but it was presumably also more likely to oversample from heavy internet users. The more time a person spends online, the greater the chance they’d happen to run into the authors recruitment ad. People who only check their email a couple of times a week would be very unlikely to participate in the study. So the bottom line is, the 1.2% figure the authors arrive at is almost certainly a gross overestimate. The true proportion of people who meet the authors’ criteria for internet addiction is probably much lower. It’s hard to believe the authors weren’t aware of the issue of selection bias, and the massive problem it presents for their estimates, yet they failed to mention it anywhere in their paper.

Second, the cut-off score for being placed in the IA group appears to be completely arbitrary. The Internet Addiction Test itself was developed by Kimberly Young in a 1998 book entitled “Caught in the Net: How to Recognize the Signs of Internet Addiction–and a Winning Strategy to Recovery”. The test was introduced, as far as I can tell (I haven’t read the entire book, just skimmed it in Google Books), with no real psychometric validation. The cut-off of 80 points out of a maximum 100 possible as a threshold for addiction appears to be entirely arbitrary (in fact, in Young’s book, she defines the cut-off as 70; for reasons that are unclear, M&G adopted a cut-off of 80). That is, it’s not like Young conducted extensive empirical analysis and determined that people with scores of X or above were functionally impaired in a way that people with scores below X weren’t; by all appearances, she simply picked numerically convenient cut-offs (20 – 39 is average; 40 – 69 indicates frequent problems; and 70+ basically means the internet is destroying your life). Any small change in the numerical cut-off would have translated into a large change in the proportion of people in M&G’s sample who met criteria for internet addiction, making the 1.2% figure seem even more arbitrary.

Third, M&G claim that the Internet Function Questionnaire they used asks respondents to indicate the proportion of time on the internet that they spend on each of several different activities. For example, given the question “How much of your time online do you spend on e-mail?”, your options would be 0-20%, 21-40%, and so on. You would presume that all the different activities should sum to 100%; after all, you can’t really spend 80% of your online time gaming, and then another 80% looking at porn–unless you’re either a very talented gamer, or have an interesting taste in “games”. Yet, when M&G report absolute numbers for the different activities in tables, they’re not given in percentages at all. Instead, one of the table captions indicates that the values are actually coded on a 6-point Likert scale ranging from “rarely/never” to “very frequently”. Hopefully you can see why this is a problem: if you claim (as M&G do) that your results reflect the relative proportion of time that people spend on different activities, you shouldn’t be allowing people to essentially say anything they like for each activity. Given that people with high IA scores report spending more time overall than they’d like online, is it any surprise if they also report spending more time on individual online activities? The claim that high-IA scorers spend “proportionately more” time on some activities just doesn’t seem to be true–at least, not based on the data M&G report. This might also explain how it could be that IA scores correlated positively with nearly all individual activities. That simply couldn’t be true for real proportions (if you spend proportionately more time on e-mail, you must be spending proportionately less time somewhere else), but it makes perfect sense if the response scale is actually anchored with vague terms like “rarely” and “frequently”.

Fourth, M&G consider two possibilities for the positive correlation between IAT and depression scores: (a) increased internet use causes depression, and (b) depression causes increased internet use. But there’s a third, and to my mind far more plausible, explanation: people who are depressed tend to have more negative self-perceptions, and are much more likely to endorse virtually any question that asks about dissatisfaction with one’s own behavior. Here are a couple of examples of questions on the IAT: “How often do you fear that life without the Internet would be boring, empty, and joyless?” “How often do you try to cut down the amount of time you spend on-line and fail?” Notice that there are really two components to these kinds of questions. One component is internet-specific: to what extent are people specifically concerned about their behavior online, versus in other domains? The other component is a general hedonic one, and has to do with how dissatisfied you are with stuff in general. Now, is there any doubt that, other things being equal, someone who’s depressed is going to be more likely to endorse an item that asks how often they fail at something? Or how often their life feels empty and joyless–irrespective of cause? No, of course not. Depressive people tend to ruminate and worry about all sorts of things. No doubt internet usage is one of those things, but that hardly makes it special or interesting. I’d be willing to bet money that if you created a Shoelace Tying Questionnaire that had questions like “How often do you worry about your ability to tie your shoelaces securely?” and “How often do you try to keep your shoelaces from coming undone and fail?”, you’d also get a positive correlation with BDI scores. Basically, depression and trait negative affect tend to correlate positively with virtually every measure that has a major evaluative component. That’s not news. To the contrary, given the types of questions on the IAT, it would have been astonishing if there wasn’t a robust positive correlation with depression.

Fifth, and related to the previous point, no evidence is ever actually provided that people with high IAT scores differ in their objective behavior from those with low scores. Remember, this is all based on self-report. And not just self-report, but vague self-report. As far as I can tell, M&G never asked respondents to estimate how much time they spent online in a given week. So it’s entirely possible that people who report spending too much time online don’t actually spend much more time online than anyone else; they just feel that way (again, possibly because of a generally negative disposition). There’s actually some support for this idea: A 2004 study that sought to validate the IAT psychometrically found only a .22 correlation between IAT scores and self-reported time spent online. Now, a .22 correlation is perfectly meaningful, and it suggests that people who feel they spend too much time online also estimate that they really do spend more time online (though, again, bias is a possibility here too). But it’s a much smaller correlation than the one between IAT scores and depression, which fits with the above idea that there may not be any real “link” between internet use and depression above and beyond the fact that depressed individuals are more likely to more negatively-worded items.

Finally, even if you ignore the above considerations, and decide to conclude that there is in fact a non-artifactual correlation between depression and internet use, there’s really no reason you would conclude that that’s a bad thing (which M&G hedge on, and many of the news articles haven’t hesitated to play up). It’s entirely plausible that the reason depressed individuals might spend more time online is because it’s an effective form of self-medication. If you’re someone who has trouble mustering up the energy to engage with the outside world, or someone who’s socially inhibited, online communities might provide you with a way to fulfill your social needs in a way that you would otherwise not have been able to. So it’s quite conceivable that heavy internet use makes people less depressed, not more; it’s just that the people who are more likely to use the internet heavily are more depressed to begin with. I’m not suggesting that this is in fact true (I find the artifactual explanation for the IAT-BDI correlation suggested above much more plausible), but just that the so-called “dark side” of the internet could actually be a very good thing.

In sum, what can we learn from M&G’s paper? Not that much. To be fair, I don’t necessarily think it’s a terrible paper; it has its limitations, but every paper does. The problem isn’t so much that the paper is bad; it’s that the findings it contains were blown entirely out of proportion, and twisted to support headlines (most of them involving the phrase “The Dark Side”) that they couldn’t possibly support. The internet may or may not cause depression (probably not), but you’re not going to get much traction on that question by polling a sample of internet respondents, using measures that have a conceptual overlap with depression, and defining groups based on arbitrary cut-offs. The jury remains open, of course, but these findings by themselves don’t really give us any reason to reconsider or try to change our online behavior.

ResearchBlogging.org
Morrison, C., & Gore, H. (2010). The Relationship between Excessive Internet Use and Depression: A Questionnaire-Based Study of 1,319 Young People and Adults Psychopathology, 43 (2), 121-126 DOI: 10.1159/000277001