On New Year’s Eve 2016, Mariah Carey had a…notable performance in which she had difficulties rendering the songs “Emotions” and “We Belong Together”. She roared back on New Year’s Eve 2017, sparking the first meme of 2018.
Alas, it is unlikely that the field of psychophysiology will un-mangle its measurement of emotions with reflexes in such a short span of time.
My lab uses two reflexes to assess the experience of emotion, both of which can be elicited through short, loud noise probes. The startle blink reflex is measured underneath the eye, and it measures a defensive negative emotional state. The postauricular reflex is a tiny reflex behind the ear that measures a variety of positive emotional states. Unfortunately, neither reflex assesses emotion reliably.
When I say “reliably”, I mean an old-school meaning of reliability that addresses what percentage of variability in a measurement’s score is due to the construct it’s supposed to measure. The higher that percentage, the more reliable the measurement. In the case of these reflexes, in the best-case scenarios, about half of the variability in scores is due to the emotion they’re supposed to assess.
That’s pretty bad.
For comparison, the reliability of many personality traits is at least 80%, especially from modern scales with good attention to the internal consistency of what’s being measured. The reliability of height measurements is almost 95%.
Why is reflexive emotion’s reliability so bad?
Part of it likely stems from the fact that (at least in my lab), we measure emotion as a difference of reactivity during a specific emotion versus during neutral. For the postauricular reflex, we take the reflex magnitude during pleasant pictures and subtract from that the reflex magnitude during neutral pictures. For the startle blink, we take the reflex magnitude during aversive pictures and subtract from that the reflex magnitude during neutral pictures. Differences can have lower reliabilities than single measurements because the unreliability in both emotion and neutral measures compound when making the difference scores.
However, it’s even worse when we use reflex magnitudes just during pleasant or aversive pictures. In fact, it’s so bad that I’ve found both reflexes have negative reliabilities when measured just as the average magnitude during either pleasant or aversive pictures! That’s a recipe for a terrible, awful, no good, very bad day in the lab. That’s why I don’t look at reflexes during single emotions by themselves as good measures of emotion.
Now, some of these difficulties look like can be alleviated if you look at raw reflex magnitude during each emotion. If you do that, it looks like we could get reliabilities of 98% or more! So why don’t I do this?
Because from person to person, reflex magnitudes during any stimulus can differ over 100 times, which means that it’s a person’s overall reflex magnitude that raw reflex magnitudes are measuring – irrespective of any emotional state the person’s in at that moment.
Let’s take the example of height again. Let’s also suppose that feeling sad makes people’s shoulder’s stoop and head droop, so they should be shorter (that is, have a lower height measurement) whenever they’re feeling sad. I have people stand up while watching a neutral movie and a sad movie, and I measure their height four times during each movie to get a sense of how reliable the measurement of height is.
If all I do is measure the reliability of people’s mean height across the four sadness measurements, I’m likely to get a really high value. But what have I really measured there? Well, it’s just basically how tall people are – it doesn’t have anything to do with the effect of sadness on their height! To understand how sadness specifically affects people’s heights, I’d have to subtract their measured height in the neutral condition from that in the sad condition: a difference score.
Furthermore, if I wanted to take out entirely the variability associated with people’s heights from the effects of sadness I’m measuring (perhaps because I’m measuring participants whose heights vary from 1 inch to 100 inches), I can use a process called “within-subject z scoring”, which is what I use in my work. It doesn’t seem like the overall reflex magnitude people have predicts many interesting psychological states, so I feel confident in this procedure. Though my measurements aren’t great, at least they measure what I want to some degree.
What could I do to make reflexive measures of emotion better? Well, I’ve used four noise probes in each of four different picture contents to cover a broad range of positive emotions. One thing I could do is target a specific emotion within the positive or negative emotional domain and probe it sixteen times. Though it would reduce the generalizability of my findings, it would substantially improve reliability of the reflexes, as reliabilities tend to increase the more trials you include (because random variations have more opportunities to get cancelled out through averaging). For the postauricular reflex, I could also present lots of noise clicks instead of probes to increase the number of reflexes elicited during each picture. Unfortunately, click-elicited and probe-elicited reflexes only share about 16% of their variability, so it may be difficult to argue they’re measuring the same thing. That paper also shows you can’t do that for startle blinks, so that’s a dead end method for that reflex.
In short, there’s a lot of work to do before the psychophysiology of reflexive emotion can relax with its cup of tea after redeeming itself with a reliable, well-received performance (in the lab).
The 50th anniversary of the TV show Star Trek‘s first broadcast is today. It was a formative franchise for me growing up, informing many of my first ideas about space exploration, heroism, and a collaborative society. Debates redound about the best episode of the series. However, I agree with Business Insider’s choice of the episode Balance of Terror. It’s essentially a space version of submarine warfare, for which I’ve been a sucker ever since the game Red Storm Rising for the Commodore 64. This episode has everything: Lore building of the political and technological history of the Federation, the introduction of a new opponent, a glimpse of life on the lower decks, and character development galore for multiple cast members – including a guest star.
One of the moments that always stuck with me was one in the Captain’s quarters as the Enterprise and its Romulan counterpart wait each other out in silence. Dr. McCoy comes to speak with Captain Kirk, who expresses a rare moment of self-doubt regarding his decisions during tactical combat. The doctor’s compassionate nature comes through as he reminds the captain how across 3 million Earth-like planets that might exist, recapitulated across 3 million million galaxies, there’s only one of each of us – and not to destroy the one named Kirk. The lesson of that moment resonates 50 years later and is one I like to revisit when I feel myself beset by doubts about myself or my career.
Another moment I appreciate is the imperfection allowed in Spock’s character without being under the influence of spores, temporal vortices, or other sci-fi contrivances. Already, he has been accused of being a Romulan spy by a bigoted member of the crew who lost multiple family members in a war with the Romulans decades before visual communication was possible. Now, Spock breaks the silence under which the Enterprise was operating with a clumsy grip on the console he is repairing. Is this the action of a spy? Or just an errant mistake that anyone could make, especially when under heightened scrutiny?
Indeed, this error might be expected when Mr. Spock operates under stereotype threat. Just hours earlier, he was revealed to share striking physiological similarities with the Romulan enemies, who Spock described as possible warrior offshoots of the Vulcan race before Vulcans embraced logic. This revelation caused Lt. Stiles, who had branches of his family wiped out in the prior war with the Romulans, to view Spock with distrust and outright bigotry that was so blatant that the captain called him on it on the bridge. Still, Stiles’s prejudice against Spock is keenly displayed throughout the episode, making it more likely that Spock would conform to the sabotaging behavior expected of him by his bridgemate.
On their own ship, the sneaky and cunning Romulans were not depicted as mere stereotypes of those adjectives but instead as a richly developed martial culture. Their commander and his centurion have a deep bond that extends over a hundred campaigns; the regard these two have for each other is highlighted in the actors’ subtle inflections and camaraderie. The internal politics of the Romulan empire are detailed through select lines of dialog surrounding the character of Decius and the pique that character elicits in his commander. In the end, the Romulan commander is shown to be sensitive to the demands of his culture and his subordinates in the culminating action of the episode, though the conflict between these and his own plans is palpable.
The contrast between Romulans and Spock highlights how alien Vulcan logic seems to everyone else. Spock is a character who represents the outsider, the one struggling for acceptance among an emotional human crew even as he struggles to maintain his culture’s logical discipline. Authors with autism have even remarked how Spock helped them understand how they perceive the world differently from neurotypicals in a highly logical fashion. However, given the emotional militarism of the Romulans, I believe that Vulcan logic is a strongly culturally conditioned behavior rather than a reflection of fundamental differences in baseline neurobiological processing.
There are neurobiological differences in sustained attention to different kinds of objects in autism compared to neurotypical controls. Work I did in collaboration with Gabriel Dichter has demonstrated that individuals with autism spectrum disorders have heightened attention to objects of high interest to these individuals (e.g., trains, computers) compared to faces, whereas neurotypicals show the opposite pattern of attention (access here). Based on decades of cultural influence, Mr. Spock might be expected to show equal attention to objects and faces, but Dr. McCoy, Captain Kirk, and the Romulans all would be expected to be exquisitely sensitive to faces, as they convey a lot of information about the social world.