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Saturday, February 22, 2014

"Love at first sight is a myth," say Chicago researchers


Social Neuroscience power couple, John T. Cacciopo and Stephanie Cacciopo


This, my friends, is a belated Valentine's Day tale that went oh so wrong...


On Feb 14, Scientific American ran a piece about When Scientists Are Mad about Each Other. The cutesy narrative on the Cacciopos described a wonderful story of love at first sight:
He was studying loneliness and isolation. She was studying love and desire. When they found themselves together, they gravitated toward her end of the continuum of social connection.

John Cacioppo was living in Chicago and Stephanie Ortigue in Geneva when they met—in Shanghai. ... On the last night of the conference, they happened to be seated next to one another at an official dinner, and soon became absorbed in conversation. “She was wonderful and brilliant and funny and I was completely taken by her,” Cacioppo says.

They both felt the chemistry but had to return to their respective homes the next day. Before parting ways they walked out of the restaurant together and noticed a beautiful moon hanging over the city. He snapped a picture of it. “A couple weeks later, she e-mailed me and asked if I could send her the picture,” Cacioppo says—a request his wife now confesses was just an excuse to strike up another conversation.

Within weeks they arranged to meet again, and from there their love unfurled. ... Within eight months they were engaged, and a season later they had married.

Their romantic story and collaborative work has been covered by a number of professional and popular media outlets, including the press office at the University of Chicago. The newsroom issued a press release on February 13, 2014 to coincide with Valentine's Day:
Researchers find brain’s ‘sweet spot’ for love in neurological patient

A region deep inside the brain controls how quickly people make decisions about love, according to new research at the University of Chicago.

The finding, made in an examination of a 48-year-old man who suffered a stroke, provides the first causal clinical evidence that an area of the brain called the anterior insula “plays an instrumental role in love,” said UChicago neuroscientist Stephanie Cacioppo, lead author of the study.

The study (Cacioppo et al., 2013) showed no such thing (in my opinion), and I'll return that in a moment. But for now I'll point out the Cacioppo spin didn't translate so well to other reports about this neurological patient. According to the Fox News affiliate in Little Rock, AK:
Love at first sight does not exist, claim researchers in the Current Trends in Neurology journal.

A stroke patient had a damaged anterior insula -- which is the part of the brain which controls how quickly we fall for someone.

They found that he could make decisions about lust normally but needed longer to think about love.

The researchers say this finding "makes it possible to disentangle love from other biological drives".

The Chicago researchers never said that love at first sight is a myth. But that didn't stop the British tabloid Metro from running that headline, while the Times of India declared:
'Love at first sight' doesn’t exist!
Feb 18, 2014, 04.52 PM

A new study suggests that love at first sight is a myth and it does not exist.

According to the study, the speed at which we fall for someone is controlled by a region in the brain called the anterior insula, Metro.co.uk reported.

All this curt tabloid fodder contradicts the meet-cute trope of the Cacciopo's own relationship. But their study itself is also quite problematic. It doesn't support the authors' contention, in my view, and here's why.


The Martin Lindstrom School of Anterior Insula Studies

Remember this classic op-ed piece in the New York Times?
You Love Your iPhone. Literally.

By MARTIN LINDSTROM
Published: September 30, 2011


WITH Apple widely expected to release its iPhone 5 on Tuesday, Apple addicts across the world are getting ready for their latest fix.

But should we really characterize the intense consumer devotion to the iPhone as an addiction? A recent experiment that I carried out using neuroimaging technology suggests that drug-related terms like “addiction” and “fix” aren’t as scientifically accurate as a word we use to describe our most cherished personal relationships. That word is “love.”
. . .

...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.

Here Lindstrom committed the logical fallacy of reverse inference – one cannot directly infer the participants' cognitive or emotional state from the observed pattern of brain activity in neuroimaging experiments. 1 Fortunately, Russ Poldrack and Tal Yarkoni (and I) wrote posts about the debacle: NYT Editorial + fMRI = complete crap and the New York Times blows it big time on brain imaging and Neuromarketing means never having to say you're peer reviewed. We all corrected the completely erroneous assumption that activation of insular cortex = love.

As Dr. Poldrack said:
In Tal Yarkoni’s recent paper in Nature Methods [PDF], 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!

Here's where the Cacciopos and their anterior insulae come in...


The Common Neural Bases Between Sexual Desire and Love

That was the title of a review article that conducted a statistical meta-analysis of the neuroimaging literature on "love" compared to "lust" (Cacioppo et al., 2012). The emphasis was on the similarity of brain regions activated by purported experimental elicitors of these complex behavioral and cognitive states (e.g., "look at a picture of your spouse" vs. close friend, or "watch porn" vs. non-porn). However, they did report a "gradient" of differential activation from the anterior "love" insula to the posterior "lust" insula, as shown below.



Fig. 1 (modified from Cacioppo et al., 2012). Brain networks related to sexual desire (blue) vs. love (red). (B) Lateral view of regions uniquely activated by desire based on the quantitative multilevel kernel density analysis. (C) Regions uniquely activated by love.


In their more recent paper, Cacioppo et al. (2013) wanted to move beyond correlational data by testing a neurological patient with damage in the anterior insula. This is generally a good strategy to evaluate whether your highly vaunted theory based on fMRI data can hold up to causal manipulations, or in this case an accident of nature. If a person with anterior insula damage cannot feel love, then you'd say that region is necessary for feelings of love. If their ability to love is unaffected, then you'd say the anterior insula is not very important.

We can go even further and ask if that patient with damage to anterior insula – but sparing of posterior insula – can still feel lust but not love. In that case, you'd say there's a dissociation between love and lust in the anterior vs. posterior insula. 2 

But that's not what the study was about!! Instead, it was about a speeded response task: look at pictures and quickly decide whether the person evokes feelings of love (or desire, in separate blocks). From the outset, I'll say that reaction times (RTs) in this task really have nothing to do with love, even as it was conceived in the fMRI experiments (i.e., "look at a picture of your spouse" and even "look at a picture of your child" - !!)

The participant in the study was a 48 year old heterosexual man who had a stroke affecting a fairly large portion of the right insula [I think], which is good for the investigators because "lust" seems to "localize" to the left posterior insula in their schematic above. We don't know a whole lot about this man (like, how long ago was his stroke?), other than that "At the moment of evaluation, the patient showed no symptoms and his neurological exam was normal." We'll just have to trust them on that...

Oh, and he was cognitively normal on some brief screening tests, not depressed or anxious, and fine in two social cognition tasks (including empathy for pain, a task where other persons with anterior insular lesions show deficits).

On to the task. The patient and 7 age- and sex-matched controls viewed 40 pictures in blocks of 20. In two of the blocks, the participants decided whether the sexily dressed girl/young woman (aged 18-30) in the photo was "relevant to sexual desire" (yes/no) or "relevant to love" (yes/no). Each image was viewed twice. Only the RTs on "yes" responses were evaluated, for some unknown reason, so we don't know if the patient was faster/slower than controls to reject a photo.




The patient behaved similarly to controls in the "lust" task. It took him just under a second, 926 milliseconds (ms), to respond "yes" when he desired the sexy young girl in the picture, compared to 959 ms for controls [remember, these guys are 48 and the girls are as young as 18], which did not differ. The patient said "yes" to lust 58% of the time vs. 61% for controls. The authors write (PDF):
The anamnesis indicated that the patient was unaware of any differences in his feelings of love or desire, whereas behavior testing revealed a selective deficit for love (but not sexual desire).

In the "love" task, the patient said "yes" to love 35% of the time vs. 43% for controls (which again did not differ). For RT, the patient took 1279 ms to say "yes" to love vs. 1020 ms for controls. And this constitutes his selective deficit for love!! It took him 259 ms longer to decide that a stranger in a photo in a laboratory task was "relevant to love." And we don't know how long it took him to say "no." And he reported no subjective change in his feelings of love, and no significant others or family or friends were queried about this.

The patient could have been slower to make that decision for any number of reasons that have nothing to do with “playing an instrumental role in love.” I won't belabor the point, but this particular region of the brain is implicated in many different functions.

With all due respect to the authors, I don't understand how this paper was published in its current form.3 

Might as well do fMRI and neuropsychological studies of Celebrity "F#@k, Marry, Kill"...






Footnotes

1 See papers by Aguirre (2003) and Poldrack (2006) for detailed explanations.

2 To complete the package with a double dissociation, a posterior insula lesion that affects lust but not love would confirm the hypothesis.

3 Current Trends in Neurology isn't exactly a stellar journal... it's published by Research Trends of India (not the prestigious Cell Press Trends series), and noted as "questionable" by scholarly publishing watchdog Jeffrey Beall. The paper is not listed in PubMed, nor can it be found at the journal website. A Google Scholar search only turns up a PDF at the authors' own labs.


References

Cacioppo S, Bianchi-Demicheli F, Frum C, Pfaus JG, & Lewis JW (2012). The common neural bases between sexual desire and love: a multilevel kernel density fMRI analysis. The journal of sexual medicine, 9 (4), 1048-54 PMID: 22353205

Cacioppo S, Couto B, Bolmont M ... Cacciopo JT (2013). Selective decision-making deficit in love following damage to the anterior insula Current Trends in Neurology, 7, 15-19 PDF


Dedication: For my wife.

> I love you
>
> Now and always
>
> Across space and time

3 comments:

  1. So, junior female scientist with career ambitions meets powerful, aging, male professor in a similar field. That's a new one! It must be pure love among equals, soulmates! I cannot see what other motivations may be involved (eyes rolling)...

    ReplyDelete
  2. Long live the Neurocritic. If neuroscience is going to be able to make reliable, informative contributions to everyday lives and to fields such as my own (teacher education) then we need plenty of this kind of insightful, informed review and analysis.

    ReplyDelete