Implicit Association Tests and Suicidality
While looking up data on the Implicit Association Test for my post two days ago, I came across Nock & Banaji 2007 (Prediction of Suicide Ideation and Attempts Among Adolescents Using a Brief Performance-Based Test), an interesting study which I am learning about only six years late (I’m catching up!)
They tried to use the Implicit Association Test to measure suicidal intent in psychiatric patients. This is good. Right now the technology for predicting suicidal intent in psychiatric patients is asking them very nicely “Excuse me, but do you think you’re going to commit suicide soon? Because if you say yes, we’re going to have to lock you up in a hospital against your will. But please, answer honestly!”
Okay, that’s exaggerated a little for dramatic effect. For one thing, people don’t say that last part. They just imply it. And there are various screening instruments that ask the question in a variety of ways, and with a variety of related questions (“Do you feel like life is not worth living?” “Have you formulated a specific plan?” “Have you bought the tools you need to carry out the plan?”) and then those screening instruments have been validated ad nauseum. And many people considering suicide really want help and are happy to be able to admit it and get it off their chests.
But the basic gist is still that if you want to know whether someone is going to commit suicide you don’t have many options besides asking, and some people have an incentive not to tell the truth.
The Nock & Banaji paper validates an alternate means of assessment. Implicit Association Tests, as mentioned before, are computer-based instruments where a subject has to press keys that categorize like and unlike concepts as quickly as possible. The idea is that they will be able to do this slightly faster on concepts that already seem implicitly associated to them than concepts which seem contradictory. In the most famous example, people were asked to organize the categories (white people + good adjectives) / (black people + bad adjectives) and then afterwards the categories (white people + bad adjectives) / (black people + good adjectives). In general white people were able to do the first task faster, presumably because they had stereotypes that already associated black people and negative attributes together so their implicit associations were aiding in the task rather than contradicting it. If this doesn’t make sense to you, it’ll become much clearer upon taking the test.
Anyhow, instead of working with races and adjectives, this new version of the test matches the categories (self, other) with the categories (pictures of self-harm, pictures of not-self-harm).
Self vs. other were words like “me” “mine” “I” versus “you” “them” “her”. Self-harm vs. not were pictures of scarred, cut skin versus pictures of healthy uncut skin. The theory was that if someone associated themselves with self-harm, they would have an easier time (as measured in reaction time) creating the categories (me + self-harm) and (others + not-self-harm) than the alternatives.
I’ll admit this protocol sounds to me like it would do a terrible job predicting suicidal intent. It seems like if anything it would pick out people who had cut themselves before. The authors note this, but say that they were reluctant to use actual images of suicide (person hanging from noose?) because it might “plant the idea” in people’s heads. It is conventional wisdom in psychiatry that this doesn’t actually happen (though I haven’t personally researched the evidence base for this) and I’m disappointed that the study went the self-harm angle.
Extremely mysteriously, though, the study claims that it adjusted for presence of self-harm and found no effect on its suicidality data, and so it had no qualms about taking a population consisting of both self-harmers and non-self-harmers and assuming this test on self-harm wouldn’t be confounded by that.
I will put aside my extreme skepticism and report what they found – which was that their test was able to distinguish healthy controls, people with past suicidal ideation, and past suicide attempters with accuracy of p < 0.01 in each distinction. Further, significant differences remained when they controlled for all previously known ways of detecting the suicidal – eg age, demographics, pre-existing psychiatric diagnoses.
They also claimed that their test was able to predict prospective suicide attempts. That is, two members of their study group attempted suicide in the six months after their study, and they noted that these two people had higher average scores on their suicidality test than the subjects who didn’t. But looking at their calculations, it looks like they simply compared the average score of the two attempters with the average score of the seventy-one non-attempters. This seems useless to me. The two attempters were almost certainly from either the “previous suicide attempts” group or the “previous suicidal ideation” group, so comparing them to the entire rest of the study sample can’t tell us anything about whether this new test is any better than just noting that psychiatric patients with a previous history of suicide are more likely to commit suicide than healthy controls. In fact, this whole section seemed damning-by-faint-praise; if this was the most they could say about its predictive validity, that’s a bit worrying (in the study’s defense, it did classify this as “preliminary evidence”)
Overall I am very excited that work is being done in this area, but a bit skeptical about this study in particular. The self-harm aspect really bothers me and their claim that controlling for it doesn’t change anything needs more proof. In particular, they controlled for presence of past self-harm but not amount of past self-harm, and it seems totally plausible that people who self-harmed themselves more in the past are more suicidal.
But the biggest uncertainty is how useful this will be. The Holy Grail would be some test you could give someone, see they’re suicidal, place them in a hospital for a few days until they’re no longer suicidal, give them the test again to prove they’re no longer suicidal, and let them out when you see their test scores have improved. But for all we know, this method could test only extremely long-term constructs, something along the lines of whether you’ve ever harmed yourself or considered harming yourself. That would be useless for seeing whether someone’s suicidal now, and useless for determining whether they’ve stopped being suicidal after some treatment. The study’s extremely half-hearted attempts to analyze prospective data don’t reassure me here.
Still, I’m glad people are finally realizing the what I’ve been saying for years, which is that the IAT is really powerful and needs to be used for something other than nebulous social justice projects. I bet if the CIA created a (self/other + patriotic American/Russian double agent) Implicit Association Test it would totally work. In the absence of that, I will just hope for more research on this suicide thing.