I Am Spartacus! You Might Be Spartacus, Too

So the Judge Rotenberg Center has been in the news again, this time because of an article in New York magazine about Andre McCollins, a young man from Brooklyn who had been sent there in 2001, when he was sixteen. His mother had sent him there because she thought it looked like a pleasant place, with dedicated and competent staff, where he might learn to control the rage attacks he sometimes had. 

Here's the part of the New York article where she talks about what motivated her to enroll him there; it very much gives the impression she didn't know how brutal the disciplinary regime was going to be:

She called the Board of Education for help finding a new school, and an employee told her about the Rotenberg Center. Stepping inside for the first time, Cheryl [McCollins] was dazzled by the décor. There was nothing institutional about this place; the carpet felt five inches thick. "I thought the place was beautiful," she recalls. "I thought these people really took pride in what they did." She loved that residents lived in lavishly decorated houses -- not dorms. The boys wore button-down shirts and dress pants. And there were surveillance cameras everywhere; she couldn't imagine a better way to ensure that Andre wouldn't be victimized again. 

School officials told her about their program and explained how the electric-shock device worked. The staffers showed her a video, too, of other students who'd been hooked up to the GED ["Graduated Electronic Decelerator," the name for the shock device] and appeared to have been completely transformed by it. "I was so excited," she says. "I was like, 'He's going to be cured? This can really stop all those behaviors, the aggression? And he won't break up my furniture, he won't fight?' 'Yes, this device does it.' I was like, 'Wow! You're kidding! Why didn't anyone tell me about this before?'"  

Twenty months into his stay there, Andre McCollins was strapped down and shocked repeatedly for a period of seven hours. The way punishment at the JRC works, they have a list of "behaviors" targeted for each person. Whenever the person does something on the list, they get a shock. Andre's list apparently included such things as screaming and tensing up his entire body, which he did throughout his seven-hour ordeal.

I have to say now that I really, really identify with Andre, even more than I normally identify with the victim in such cases of abuse of disabled children or dependent adults. Andre and I share several things: we're the same age, both born in the year 1984 (poor, poor Andre, he has seen the inside of Room 101), both diagnosed with a pervasive developmental disorder in early childhood. 

Most importantly, we share a pattern of behavior.

The "full-body tense-up."

Obviously, I'm not Andre and I can't tell you what's going through his head when he tenses up his entire body, but I can tell you what it's like when I do it. 

First, some background: though I can speak fluently, I can really only do it when I'm not doing anything else. If I'm intent on something, I won't answer you if you speak to me. I probably won't even acknowledge you until a few minutes later, or until I can tear myself away from whatever it is I'm doing. Especially if I'm doing something mentally taxing, especially something nonverbal and mentally taxing, like math, I may need to wait a few beats to remember how to speak: what the words are, how to put them together in ways that make sense. 

I don't have to be doing hard or creative work for this problem to arise: physical pain and emotional stress are also mentally taxing, and also effectively put words out of my reach for a while. 

As such, my primary response to fear or pain has never been to vocalize. Most of the time it just doesn't occur to me. I react with my body instead, stiffening my posture, recoiling back and tensing every muscle simultaneously. (Sometimes when I'm in pain I also make a hissing noise, but not always). This is what I do whenever anyone touches me. I have reacted that way to touch since I was a baby: my mom says I used to stiffen up in her arms when she tried to hold me. 

It is, you might imagine, a completely involuntary reflex.

So, when I got to this part of the article (TRIGGER WARNING) ---

Usually after Andre got a shock and was restrained, he'd calm down, but on this day he only got more agitated. The more upset he became, the more he tensed up his body -- and the more he tensed up, the more shocks he received. Between 10 a.m. and about 11 a.m., the workers shocked him fourteen times. Each press of the button delivered a loud, high-pitched alarm -- informing employees the shock had been delivered -- while Andre's cries echoed down the hall.

"No, don't do that!"

"I'm sorry. Sorry. Sorry." 

"I won't do it again."

"No, please."

"Stop! Stop! For real!"

"Help me! Help! Help!"

Employees came and went throughout the morning and into the afternoon. They attached two more electrodes, so Andre had five total: on both arms, both legs, and his torso. Following the usual protocol, they tested the batteries on his shock device; rotated his electrodes so they wouldn't leave marks on his skin; offered him water. They studied his "behavior recording sheet" to figure out exactly what behaviors they were supposed to punish. And they documented each shock with the reason it was given: "Scream" or "Tense Up." 

Hour after hour went by and nobody knelt down next to Andre to try to calm him. Attention was considered a reward -- and a student who's exhibiting "targeted behaviors" is not supposed to receive any. When the staffers did speak to Andre, they were required to follow a script, like a case manager did at 1:25 p.m., when she pressed the button for shock eighteen, then said: "Andre, no full-body tense-ups." If any of the workers thought these shocks were excessive, they kept it to themselves. They all knew that if they didn't shock a student when they were supposed to, the phone in the classroom would ring and there would be a monitor on the line ordering them to press the button. 

--- I felt horror, not only at what they were doing to him, but also because they escalated it whenever he physically reacted to the pain. When you realize that, and let it sink all the way in, you see how easily they could have killed him that day. The perverse logic --- tensing up his body (showing fear and pain) is bad, so we will shock him (make him feel fear and pain) whenever he does it until he stops --- reminds you of other no-win scenarios, like the witch trials where they would determine an accused witch's innocence based on whether she sinks or floats in water. If she floats, she's guilty, and her accusers have grounds to kill her; if she sinks, she was innocent, but she's dead anyway.

By now, you're probably asking, "Why is this woman* going on at such lengths about her feelings, and her weird stiffening-up reflex? What does any of this have to do with Andre McCollins?" 

That's a fair question --- I'm not Andre, and I don't have any better idea than you do what he was thinking or feeling on that day. But because of all the things I do happen to have in common with him, I get a strong sense of "there but for the grace of God random chance go I" from his story.

I also believe there's a very strong tendency for non-disabled people to "other" people like Andre McCollins --- they might be horrified at what happened to him, but at the same time they know how impossible kids like him can be. They're aggressive. Violent. They can't be reasoned with. They're a "they," never a "we." People might think they ought to be treated more gently than they are at the JRC, but they have to be put somewhere, controlled somehow, ... don't they?

That's why I have made this post so personal. I'm not Andre, but I share some things with him, and more than anything I think people need to see articles from people who are like Andre in various ways saying, unambiguously, "THIS IS NOT OKAY. IT WOULD NOT BE OKAY IF YOU DID IT TO ME, AND IT IS NOT OKAY THAT YOU HAVE DONE IT TO HIM." If I come across anything Andre himself has written, I will link to it.

*Bitch, to the uncharitable. Cunt, to the vulgar. Perhaps "mewling quim," if you are Loki.

More Autistic Strengths: Symmetry-Spotting

EXECUTIVE SUMMARY: A recent study has added to the list of cognitive strengths peculiar to autism: in this study, a group of autistic teens/young adults and a group of age-, IQ-, sex- and eyesight-matched control subjects were shown a series of paired images, all of them different arrangements of lots and lots of tiny black-and-white dots, and determine which of the two images has some of the dots arranged in a symmetric pattern. Consistently, the autistic young people were able to pick out the symmetrical images at lower signal-to-noise ratios (i.e., with smaller proportions of the dots possessing mirror images) than their non-autistic peers.
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Michelle Dawson and Laurent Mottron have done lots of research on perception and cognition in autism --- particularly visual processing. (Morton Ann Gernsbacher is another frequent collaborator, but she didn't participate in the research I'm about to describe).

Their research has identified several cognitive strengths* specific to autism: enhanced sensitivity to pitch; enhanced sensitivity to, and recall of, details (without any corresponding loss of ability to see the big picture); ability to switch between different strategies (big-picture vs. small details) as needed; . Autistic people also do a lot better on one particular IQ test, Raven's Progressive Matrices, than you would predict based on their scores on other IQ tests (e.g., various Wechsler tests).

A new skill has just been added to this constellation: the ability to quickly determine whether a complex pattern is symmetrical or not.

In a study published this past spring in PLoS ONE, a group of Canadian researchers --- Mottron and Dawson, along with three others: Audrey Perreault, Rick Gurnsey and Armando Bertone --- had participants look at very complicated, visually "busy" patterns of small dots arranged on a video screen and determine, in the very short time the pattern remained onscreen (250 milliseconds), whether it was symmetrical or not. (They were shown two different patterns, one symmetrical and one not, and they had to identify the symmetrical one.)

Here's an example of the kind of image they would have to categorize:
(If it looks obvious to you, remember they only got a fraction of a second to look at it!)

The images were all just black and white, except for the one colored dot in the center, where the participants were told to focus their attention. In the above image, which is 100% symmetrical, each dot has a twin, the same size and color, placed so that they would lie one on top of the other if you printed the image out and folded it along its axis of symmetry. In that image, you can see that the vertical axis is the axis of symmetry; some images are symmetrical along the horizontal axis, and others are symmetrical along an oblique axis, the line y = x in a Cartesian coordinate plane with the colored dot at the origin.

These shapes are symmetrical about the horizontal (x) axis:
These shapes are symmetrical about the vertical (y) axis:

The pink and green curves are symmetrical to each other about the line y = x (blue)

Some of the images were also only partially made up of symmetrically-paired dots; the study participants were supposed to identify which of the two images shown to them had any degree of symmetry at all. (It was always just one; I guess you could design an experiment where both of the images had some degree of symmetry and the participants had to determine in which the degree of symmetry was greater, but that would be harder than just picking out which one had any degree of symmetry at all.)

The two groups whose performance was compared in this study were a group of 14** autistic young people (ages 14 to 35) and 15 typically-developing young men matched with the autistic subjects for age, IQ and visual acuity.

The criterion used to compare the two groups was "symmetry detection threshold", or the proportion of dots in a symmetrical design that had to have mirror images before a given person could identify the symmetrical design 75% of the time. Average detection thresholds were compared across groups, and also across what type of symmetry the image displayed. Both groups did best at spotting symmetry along a vertical axis, and both groups did the worst at spotting it across the line y = x.

But for all of these conditions, the autistic people had lower detection thresholds --- they correctly found symmetry more often in patterns that had less of it, relative to background noise --- than their non-autistic peers.

The study authors see this as indicative of our (autistic people's) ability to look at things more than one way simultaneously. (Another recent study, not referenced in this one, also found something suggestive of that: autistic people were better able to reproduce "ambiguous figures," or line drawings that look like they could be one of two things, depending on how you look at them). They also see their results as incompatible with the "weak central coherence" theory of autism, which explains our relatively keen collective eye for detail as a deficit in big-picture thinking. But this symmetry-spotting task requires both processes at once --- local-level, small detail perception for checking individual dot pairs to see if they really are exactly symmetrical, and also larger-scale, "gestalt" perception of whole shapes created by all the dots together.

Perreault, A., Gurnsey, R., Dawson, M., Mottron, L., & Bertone, A. (2011). Increased Sensitivity to Mirror Symmetry in Autism PLoS ONE, 6 (4) DOI: 10.1371/journal.pone.0019519

*Other, earlier research has also identified autistic strengths: as early as 1983, Amitta Shah and Uta Frith discovered that autistic children did especially well at disembedding figures; those two researchers were also the ones who identified the other really well-known "islet of ability", in the Block Designsection on various IQ tests.

**There were originally 17 people in that group, but three of them couldn't do the experimental task, so they did not contribute any data.

Fetal Testosterone and Autistic Traits - Part V: Visuospatial Abilities

EXECUTIVE SUMMARY: Researchers looking into the separate questions, "How do male and female minds differ?" and "How do autistic people differ from non-autistic people?" have discovered --- independently of each other --- an assortment of cognitive strengths peculiar to each of the groups being studied. Now that Simon Baron-Cohen has floated the idea that autism is just an extreme version of the normal male brain, it would make sense to check if the cognitive strengths of autistic people, and of all men, really do overlap, and whether prenatal testosterone exposure seems to play any role in the development of any of those aptitudes.

One recent study (Falter et al., 2008) compared groups of autistic and typically developing schoolchildren on three visual/spatial tasks that normally show a male advantage: mentally rotating three-dimensional objects, positioning a cursor over a moving image, and spotting a shape hidden somewhere in a larger pattern or line drawing, or "figure disembedding". They also measured the children's second-to-fourth digit ratios, as an indicator of prenatal testosterone exposure.

Their results were not consistent with what they predicted based on the extreme-male-brain theory of autism: the autistic children did better at figure disembedding, worse at targeting the moving image, and were slightly faster (but not more accurate) at mental rotation. On further analysis, though, they seemed to be faster at different parts of the (complex, multi-step) mental-rotation process than non-autistic men seem to be. The researchers were able to break down the results of the mental-rotation task into "rotational" and "non-rotational" components --- that is, to separate the actual visualization of the object rotating from the other factors, like comparing the rotated object in your head to the one shown on the screen and deciding whether they are the same. Autistic people seem to be faster at the non-rotational parts of this process, while non-autistic, male people seem to be faster at the rotational part. So, different cognitive skills underlie the two groups' respective advantages at the same complex task.

Finally, testosterone seemed to play no role whatsoever in predicting a child's success at either mental rotation or figure disembedding; the only task that showed a relationship between digit ratios and performance on that task was targeting, which 1) was harder for the supposedly "hyper-masculine" autistic boys, and 2) was easiest for the boys with middling digit ratios --- the ones with very low, "masculinized" digit ratios performed worse, as did the ones with high, "feminized" digit ratios. There were also no group differences in digit ratio between autistic and non-autistic boys.

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The term "visuospatial abilities" covers a lot of ground, and might include different skill sets depending on where and how it's being used.

For example, one of the most-studied (and most reliably replicated) cognitive differences between the sexes is a male advantage in the ability to rotate three-dimensional images on one's head; other spatial skills that tend to show a male advantage are aiming, predicting a projectile's trajectory . If autism is the same thing as having an "extreme male brain," you would expect autistic people to do better at these tasks than non-autistic people of their same gender.

There is also a well-established constellation of visual and spatial skills that autistic people tend to be better at than non-autistic people: the Block Design subscale of the Weschler intelligence tests, spotting a shape hidden inside a larger pattern (i.e., disembedding a figure), distinguishing a target figure from a crowd of "distractor figures" that are similar but not identical to the target, and reproducing a distorted or impossible image. It would be equally instructive, as far as investigating the extreme-male-brain hypothesis is concerned, to look for sex differences in how non-autistic people do on these tasks; you would also want to look for a relationship between those abilities and prenatal testosterone exposure. If the autistic cognitive style is essentially the same as the masculine one, you would predict exposure to higher levels of testosterone in utero would correlate with higher scores on the Block Design, faster and more accurate performance on visual-search tasks (like the Embedded Figures test or the tasks described in this study), and greater accuracy on drawing tasks, like the perspective-drawing task described here or the shape-drawing task described here (PDF).

One relatively recent study, carried out by Christine Falter, Kate Plaisted and Greg Davis and published in the Journal of Autism and Developmental Disorders, directly addresses the prediction I made in the second paragraph. Those researchers identified three visuo-spatial tasks that usually show a male advantage (or correlate with prenatal testosterone exposure, or both) --- mental rotation, targeting and figure-disembedding --- and tested a group of 28 autistic schoolchildren (27 of whom were boys) and a group of 31 typically-developing children matched for age, sex and nonverbal IQ on those tasks. They also measured the children's second-to-fourth digit ratio, as an indirect measure of prenatal testosterone exposure.

(Sample image from the Embedded Figures Test)

They found no significant differences between the autistic children and the typically-developing children in terms of digit ratio; depending on how the study participants were grouped (because each skill was tested in a differently-sized subset of the total study population), either the autistic half or the neurotypical half of a given subgroup might have slightly higher 2D:4D. These differences were so slight as to be statistically insignificant, regardless.

Overall, the autistic children did better at both mental rotation of 3-D objects (measured by having the children turn a computer-generated image of a solid to match the view of that solid the computer showed them) and figure disembedding than the typically-developing children; they were both faster and more accurate at these tasks. (Although, for the mental-rotation task, the difference was very slight). However, they performed worse than the typically-developing children at the targeting task, in which they had to position a cursor over an image that would appear at random points within certain regions of the computer screen*. Also, the mental-rotation results are a bit more complicated than just looking at the mean reaction times and accuracies of both groups would lead you to believe. The study authors did a linear regression of each of those two outcome variables with the degree of rotation (i.e., how far from its original position did the participants have to rotate the object?), which apparently allowed them to separate out the different cognitive processes used in mental rotation:

Across participants, the degree of rotation showed a strong linear relationship with reaction time, RT (R = .99, F(1,3) = 227.88, p = .001), and accuracy scores, ACC
(R = .98, F(1,3) = 59.84, p = .004). Accordingly, consistent with previous studies of mental rotation, RT and ACC were each regressed linearly against angle of rotation for each participant, to yield a rotation slope and an intercept. The slope for each participant indexed the speed with which they mentally "rotated" objects in degrees per second. The intercept yielded by these regressions indexed non-rotational aspects of performance, presumably related to the speed with which participants mentally compare three-dimensional objects as well as decision making and response variables.

Only the linear regression for reaction time showed any difference between the autistic and typically-developing groups, and there the difference was only in the intercept; the slopes of the two groups' lines were more or less the same.

(Figure 1, in Falter et al., 2008 --- graph showing the linear relationship of degree of rotation with reaction time)

Since two of the three authors of this paper (Falter and Davis) had also been involved in a similar study comparing men and women, using the same linear-regression method in their analysis of their results, they were in a position to notice differences between the men's results in the 2006 study and the autistic children's results from the 2008 study.

While both of the studies found overall differences that seem to lend support to Baron-Cohen's hypothesis --- men outperformed women, and autistic boys** outperformed typically-developing boys --- the linear regressions of both sets of data revealed different factors contributing to each better-performing group's advantage: while the autistic group in Falter et al. (2008) seemed to be better at the non-rotational aspects of this task, the male group in Falter et al. (2006) was faster at performing the rotations themselves. (In other words, if you were to compare the graphs made of the linear regressions of their results, the graphs in the 2006 study would have different slopes, while the graphs in the 2008 study have about the same slope, but different intercepts).

(Figure 2, in Falter et al., 2008 --- graph showing relationship of second-to-fourth digit ratio to reaction time on Targeting task)

Neither the mental-rotation task nor the figure-disembedding task showed any relationship to digit ratio; however, there was a quadratic relationship between 2D:4D and reaction time on the targeting task, with children having both very high (above 1.0) and very low (below 0.90) digit ratios taking longer to position the cursor correctly than their peers with mid-range digit ratios.

An older study, carried out in 1992 by Jo-Anne Finegan, G. Alison Niccols, and Gabriel Sitarenios, compared testosterone levels in the amniotic fluid of women who had undergone amniocentesis at Toronto General Hospital during the mid-1980s with those women's children's later results (at age four, in this study) on a wide range of cognitive tests.

The visuospatial tasks included in this study were fairly similar to the ones Falter, Plaisted and Davis used: there was a figure-disembedding task (the Preschool Embedded Figures Test, in which a triangle is hidden somewhere in various line drawings of familiar objects), a block-building task, in which the person giving the test builds structures of varying complexity out of 1-inch cubes, and the child is supposed to build the same thing. It's not the same as the Block Design test, but it seems pretty close to it to me. The one thing Falter et al. test that Finegan et al. do not is targeting, and Finegan et al. test a few things Falter et al. don't: picture-puzzle solving (which I guess is also analogous to Block Design) and geometric-form copying (analogous to the drawing tasks I mentioned above, in the paragraph about autistic people's visuospatial strengths).

(Sample image from the Preschool Embedded Figures Test)

That study found no significant sex differences in any of the skills being investigated; it also found no relationship between prenatal testosterone and performance of three of the four tasks I describe above --- figure disembedding, puzzle solving and shape drawing were all independent of prenatal testosterone exposure in both sexes. For girls, there was a significant negative relationship between prenatal testosterone and scores on the block-building task --- the higher female scorers on this test tended to have lower levels of prenatal testosterone exposure than their lower-scoring peers; for boys, there was a small trend in the opposite direction --- with high scorers tending to have higher prenatal testosterone levels --- but that relationship wasn't statistically significant.

Falter et al.'s results tell me that the area of overlap between 1) the things men are usually found to better at than women, and 2) the things that autistic people are usually found to be better at than non-autistic people, within the larger domain of visuo-spatial skills, is fairly small. Also, the two "masculine" skills that autistic people tend to do better at --- figure disembedding and mental rotation --- are not at all correlated with an indirect measure of prenatal androgen exposure.

Because there is some uncertainty around the use of digit ratios as a marker for prenatal testosterone exposure, I wanted to find a study of similar cognitive abilities that measured that variable directly. Finegan et al.'s study was the only one I could find that did this, even though it was old and didn't have any autistic participants. Their results showed that prenatal testosterone has no effect on young children's performance at most visuospatial tasks, and, on the tasks it does influence, it seems to affect boys and girls differently, with higher levels of testosterone exposure boosting boys' scores but lowering girls'.

*It doesn't surprise me at all that autistic people would be slower at that, given our difficulties with motor planning. Even apart from that, some studies have found that we are not as good as neurotypical people in tracking moving visual stimuli --- see this review (full text here) for more detail.

**I use "boys" here because there were a total of two girls --- one in the autistic group, and the other in the control group --- in this study population of fifty-nine children.

Sources:
Falter CM, Plaisted KC, & Davis G (2008). Visuo-spatial processing in autism--testing the predictions of extreme male brain theory. Journal of autism and developmental disorders, 38 (3), 507-515 PMID: 17674175

Finegan, J., Niccols, G., & Sitarenios, G. (1992). Relations between prenatal testosterone levels and cognitive abilities at 4 years. Developmental Psychology, 28 (6), 1075-1089 DOI: 10.1037/0012-1649.28.6.1075

Voyer D, Voyer S, & Bryden MP (1995). Magnitude of sex differences in spatial abilities: a meta-analysis and consideration of critical variables. Psychological bulletin, 117 (2), 250-270 PMID: 7724690

Is Everyone a Bit of a Synesthete?

I saw this article in the current issue of Scientific American and, once I got over the inherent silliness of the experimental setup, realized that this study's results do seem to prompt the above question.

From the SciAm article:

David Ostry [link], a neuroscientist with co-appointments at McGill University and the New Haven, Conn.-based speech center Haskins Laboratories, has been studying for years the relation between speech and the somatosensory system, the network of receptors in skin and muscle that report information on tactile stimuli to the brain. In his most recent study, published in the Proceedings of the National Academy of Sciences USA, he and two Haskins colleagues found that subjects heard words differently when their mouths were stretched into different positions. The results have implications for neuroscientists studying speech and hearing as well as for therapists looking for new ways to treat speech disorders.

The study involved seventy-five young, hearing, American-English-speaking volunteers listening to computer-generated speech (a single word, derived from recordings of a human speaker saying either "head" or "had," and then subjected to various frequency modifications) and pressing a button to indicate which word they thought they heard.

Also, they were to do this while hooked up to this thing:

That thing is a robot that's been programmed to pull on those little plastic tabs to stretch the wearer's mouth in a certain way (Fig. 1, taken from Ito et al.).

(Here's the PNAS article's description):

We programmed a small robotic device (Phantom 1.0, SensAble Technologies) to apply skin-stretch loads (Fig. 1). The skin stretch was produced by using small plastic tabs (2 x 3 cm), which were attached bilaterally to the skin at the sides of the mouth and were connected to the robotic device through thin wires. The wires were supported by wire supports with pulleys to avoid contact between the wires and facial skin. By changing the configuration of the robotic device and the wire supports, the facial skin was stretched in different directions.

(That last sentence is a good example of why the passive voice, while seemingly a good choice for scientists looking for a nice, impersonal way to write about methods without going "We did this, and then we did this and this and this" over and over again, can also be a grammatical and semantic minefield. I try never to write in passive voice without consciously asking myself, at least twice, what the subject of my sentence is!)

Anyway. I was writing about methods before my inner grammar Nazi interrupted, so let's get back to that.

The seventy-five volunteers were split into five groups of fifteen, each of which got a different sort of stimulation from the robot facehugger. Two of the groups were designated as control groups, which in this context means that the ways in which their faces were stretched bore no resemblance to any part of human speech:

We used a robotic device (Fig. 1) to create patterns of facial skin deformation that would be similar to those involved in the production of head and had. We tested 3 directions of skin stretch (up, down, backward) with 3 different groups of subjects. We also carried out 2 control tests in which we assessed the effects on speech perception of patterns of skin stretch that would not be experienced during normal facial motion in speech. One involved a twitch-like pattern of skin stretch; the other involved static skin deformation.

They found that, when participants' lips were pulled upward (like the motion used to shape the short "e" sound in "head"), they were more likely to hear the intermediate sounds as "head," while when their lips were pulled downward (like the short, nasal "a" in "had"), they were more likely to hear those same sounds as "had." Pulling the corners of the mouth straight back had no effect on which word they were likelier to hear.

One thing they didn't measure, but that I kind of wish they had, was whether the presence of extraneous sensory input (i.e., the skin stretching) had any effect on the participants' ability to register what they heard. The way the study was designed, all they could tell was how the "perceptual boundary" could be shifted one way or another --- not whether perception itself was disrupted, as I might expect it to be with such an intrusive competing stimulus!

Although, I can also see how a consistent effect that varies with the type of somatosensory stimulus would argue against any interference between the two sensory processes (i.e., hearing and touch), and would even suggest that they aren't separate processes at all.

That seems to be what the study's authors suggest:

The modulation of speech perception observed in the present study may arise as a consequence of facial somatosensory input to facial motor and premotor areas, a pattern that would be consistent with the motor theory of speech perception. However, somatosensory inputs may also affect auditory processing more directly. A number of studies have reported bidirectional effects linking somatosensory and auditory cortices. Indeed, activity due to somatosensory inputs has been observed within a region of the human auditory cortex that is traditionally considered unisensory.

That's the part that really sounds like synesthesia to me, albeit a somewhat weaker version where sensations of one type (say, a feeling of tension or pressure on facial skin) influence your interpretation of sensations of another type (say, sounds that may or may not be words), rather than creating those partnered sensations de novo, as happens in full-blown synesthesia.

Ito, T., Tiede, M., & Ostry, D. (2009). Somatosensory function in speech perception Proceedings of the National Academy of Sciences, 106 (4), 1245-1248 DOI: 10.1073/pnas.0810063106