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August 29, 2023Episode 65. Minor Stress Factors Can Cause Major Problems, Even in the Best Driving Conditions.
FEATURING: Mike Manser, Ioannis Pavlidis
Obvious pressures when we’re driving on the roadways—like aggressive drivers, stormy weather, and unruly passengers—are widely recognized. But less conspicuous triggers can compromise safety, too.
About Our Guests
Manager, Human Factors Program, TTI
Michael Manser manages TTI’s Human Factors Program. He has worked in the area of transportation safety for more than 25 years. Mike has been involved in research examining the impacts of vehicle and infrastructure-based technology on driver behavior and stress on projects conducted for the National Highway Traffic Safety Administration, Federal Highway Administration.
Director, Computational Physiology Laboratory, University of Houston
Ioannis Pavlidis is the Eckhard-Pfeiffer Distinguished Professor of Computer Science and director of the Affective and Data Computing Laboratory at the University of Houston. His research is funded by sources including the National Science Foundation, transportation agencies, and medical institutions. He has published extensively in the areas of affective computing and data science. Widely known for his work on stress and its effects on human to human and human-machine interaction, Dr. Pavlidis pioneered developing contact-free methods for measuring electrodermal activity, breathing, and heart function, which he used to study physiological arousal in naturalistic studies.
Bernie Fette (host) (00:15):
Hello and welcome to Thinking Transportation. Conversations about how we get ourselves and the things we need from one place to another. I’m Bernie Fette with the Texas A&M Transportation Institute. The circumstances that make driving stressful — high speed traffic, heavy storms, screaming children in the backseat — those are some of the stress factors that we are all familiar with. But what about less conspicuous triggers? What about the anxious feelings that creep in even when driving conditions appear to be ideal? How might those less obvious factors affect our safety and the safety of others on the road? Mike Manser is a Senior Research Scientist at TTI and Ioannis Pavlidis is the Eckhard-Pfeiffer Distinguished Professor of Computer Science at the University of Houston. They’re with us today to talk about their research that explored how driving can affect our stress levels, even in the most subtle of ways. Mike and Ioannis, thank you very much for joining us today.
Ioannis Pavlidis (guest) (01:26):
Thank you, Bernie. Pleasure to be here.
Mike Manser (guest) (01:28):
Thank you, Bernie. Appreciate it.
Bernie Fette (01:30):
You’ve both been involved in a study recently on the topic of driving and stress. And I have been eager to have this conversation ever since I heard about the study because the topic is so universal. I mean, who among us can honestly say that we’ve never felt stressed out when we’re driving somewhere. Right? At least, you know, not in the last 10 years or so, depending on where you live. So if we can, let’s begin with the questions that you were exploring in your study. What exactly were you hoping to learn?
Ioannis Pavlidis (02:04):
This is a kind of a unique study because we posed a question that is usually not the case In most driving studies. The the goal of most driving studies is to do primarily with safety. The aim of our study in contradistinction is about what is going on when everything appears to be okay.
Bernie Fette (02:30):
Ioannis Pavlidis (02:31):
Good weather, good traffic, perhaps good mood. <Laugh>
Bernie Fette (02:36):
Favorable conditions all around.
Ioannis Pavlidis (02:39):
Correct. Once you take out the apparently bad stuff and you leave what we all agree that is uh, either okay or great, is there still something left that perhaps you worry about? So that’s pretty much the goal of our study.
Mike Manser (02:57):
It’s on a practical level, it’s very important to ask this question ’cause stress can be pretty nefarious, right? It can creep in in ways that we never really expect it to creep in. We identify pretty obvious high-stress situations, situations that cause problems for the driver, heavy density traffic, it’s storming out. All these things kind of build up. Well, the question that we’re really interested in is what happens when you take away some of those very obvious stressors and what you’re left with is what appears to be a pretty normal driving conditions? Well, what in that scenario is causing stress? What are those things that are detracting from driving basically in those normal environments? That’s the real question here. We can identify high-stress situations like weather and stuff and we can make recommendations, don’t travel during that time. But it’s in those normal everyday driving conditions where stress is really hard to detect and really hard to see obvious signs of it. And to address that, you need to ask these questions because stress does lead to unsafe driving. It leads to drivers whose ability to focus on important criteria and things in the environment that tends to decrease their ability to concentrate on things can be impacted. And those are all things that gradually can build up to and lead to less safe driving. So what we’re really trying to do is understand, okay, what are those things that lead to unsafe driving and what are they in normal driving situations that do that?
Bernie Fette (04:41):
Okay, let me back up for just a moment if I can. And what I think I’m hearing is that you’re trying to help determine stress levels in a way that hasn’t been really studied before in the sense that we already know what the big stressors are. As you mentioned Mike, serious weather for instance, perhaps especially aggressive drivers on the road. Have those elements been studied also in the past and your study is kind of filling in a gap of sorts that hasn’t been examined very much?
Mike Manser (05:16):
Yeah, so a lot of those big stressors have been identified already and we have good sense of what they are from a personal experience level as well. Like if your kids are in the backseat screaming for attention and the parents having to deal with that in addition to driving, their emotional stress might go way up high. And then maybe their cognitive stress, their ability to deal with the kids in the backseat and all the other stimuli in the environment can be compromised. But for us, a lot of those stressors were identified. But we still see crashes happening in everyday driving situations in conditions that we think are actually optimal for driving — clear weather, normal traffic, going to work middle of the day, coming home. These are not really unusual situations at all. But we know that stress plays a role in reducing safety during those times. And what we’re really interested in is, okay, if we eliminate those big stressors, the ones we’ve already identified in the past and we’re left with kind of what appears to be a normal situation, are there any additional stressors that are happening that are contributing to unsafe driving in those circumstances?
Bernie Fette (06:31):
And what are some of those additional less conspicuous stressors that you’re talking about?
Mike Manser (06:38):
Yeah, I’ll turn it over to Ioannis because he has a really good sense of what those different factors were that we identified.
Bernie Fette (06:45):
Okay. What were the specifics you looked at, Ioannis?
Ioannis Pavlidis (06:48):
So we looked at a bunch of things. That was one of the unique aspects of this study. Most driving studies, they look at people only when they drive. We looked at people 24-7 because we wanted to know what’s happening when they don’t drive. Because otherwise it may come across as a stressor when you drive. But exactly the same thing you have when you don’t drive. And if you don’t follow the subjects throughout the day, you will not be able to figure this out. Right. To make a long story short, the two things that appear to be unique to driving as stressors under best possible conditions, number one is speed, how fast your car goes. And the number two is how anxious you are as a person. The more anxious, the more stressed you are when you drive without any reason. I mean perfect driving conditions, so good weather, not a lot of traffic and so forth. But if you are an anxious person, you are still stressed when you drive and not because of external factors like bad weather and bad traffic, as I said. And not because you are a novice driver. All the drivers in our study were experienced drivers. It’s something that comes from inside of you. So these two factors are always with you. Of course not all people are very anxious, right? But this we estimate is about 20 to 30 percent of the population, people who suffer from some degree of generalized anxiety.
Bernie Fette (08:31):
Okay. So would one example be someone who say carries a certain level of anxiety about their job or family life into the driving task? Is that part of what we’re talking about?
Ioannis Pavlidis (08:45):
Yeah, not only that, it’s called a generalized anxiety disorder. They’re a person who is inherently anxious. So if you are such a person and if you drive fast, which we all do in the freeway, say 65 miles per hour, these two factors in combination add about uh, nine to 10 heartbeats per minute more than you’re not a generally anxious person. And you drive in the city, say at about 30, 35 miles per hour. So this gives you a contradistinction, right? What happens when you, you drive fast and you are anxious versus when you drive slow and you are not anxious. The difference is about, uh, 10 heartbeats per minute. So instead of having 60 heartbeats per minute, you shoot up to 70, which is a significant cardiovascular load. And I repeat this is under the most ideal circumstances.
Bernie Fette (09:46):
Let’s talk a little bit about the implications of your findings. What are the stress impacts on human health for these stressful situations? Can you talk a little about both the short-term and long-term implications?
Ioannis Pavlidis (10:01):
Short-term, almost nothing. Long-term, it depends on how often and how intense, uh, that pattern is, what we call use pattern. So for example, if you’re a generally anxious person and you have a long commute to work through freeway, so you drive at high speeds, say one to two hours every day. So another, the long run, this type of stressor that I described almost certainly will have some effects on your health. So bottom line, this thing could be harmful in the long term if it is repeated very frequently.
Bernie Fette (10:42):
So a person who is generally anxious by nature and commutes even under relatively positive circumstances over a long period of time, over that time, they become at higher and higher risk of certain health maladies, one of them being heart problems. Am I reading that correctly?
Ioannis Pavlidis (11:06):
Correct. Yes. Probability for this goes up.
Bernie Fette (11:09):
Okay. Anything that you’d like to add, Mike?
Mike Manser (11:13):
The study design itself was constructed such that we are collecting data on drivers when they were driving and then also when they were just at their house. So we are collecting data virtually 24 hours a day.
Bernie Fette (11:29):
And I gotta ask though, how do you do that? ’cause that sounds unusual all by itself.
Mike Manser (11:33):
Yeah, it’s awesome that we developed basically some kind of a package of technology and software that works together to identify heart rate while you’re doing anything. So we use a smartwatch like an Apple watch, okay. And it collects heart rate, but then it runs that data through software. And then of course, Ioannis, and his talented team conduct some really nice statistics on it to determine if there are actual differences between those. So somebody gets in the study and they wear this watch essentially 24 hours a day except a little bit of time to charge it back up. And what we do is then compare how they’re responding to stress in normal driving situations like in our study, like on the highway, if they’re in their neighborhood, if they’re on their way to work or on their way home from work. And then we also collect data when they’re just doing everyday activities like at home, right? Mm-hmm. <affirmative>. And by doing that, we can identify first of all those people who have a slightly higher than normal level of stress. In this case, your heart rate is a little bit higher by nature, you’re a little bit more stressed person. But then we can compare that against when they drive. And that was key to this study. This was one of the main features that you often don’t see in a lot of other studies is that comparison between your normal stress levels and your stress levels when you’re driving.
Bernie Fette (13:06):
Is it true that being at a higher stress level can place us as drivers at a higher risk of making mistakes?
Ioannis Pavlidis (13:17):
The answer is yes. And the reason is basically because you have thinner and thinner margins in reacting to situations that may come your way. And uh, they are not very favorably.
Bernie Fette (13:33):
So for instance, the response time could be compromised.
Ioannis Pavlidis (13:36):
Response time, and even, uh, the actual reaction. You tend to not to think through your reaction. I see it stress us. It shuts down cognition and wakes up basically blind responses, which are guided by randomness rather than thoughtful, um, processes. More, the more stressed you are, the less the response is thoughtful. Actually we documenting other studies that your response becomes random. Then you know, if you’re lucky, you do the right thing because everything is a process. When we drive what we do, everything is a process. You always have a bunch of choices in front of you, go left, go right, and stop. Uh, accelerate. You know, if cognition shuts down and you react randomly, if you are lucky, you pick the right process. If you are not, you pick the wrong process. And there you have the crash.
Mike Manser (14:33):
We look at stress, we define it in a couple different ways. You can have cognitive stress, which is like a mental workload. You’re having to think harder about what you’re doing when you’re driving. There’s emotional stress. So that’s, you know, responding that you’re worried about something. And then that’s another version of stress. And that can, can be driven up. And then you have basically a physical stress. You’re actually having to manipulate or do something with your car or the environment. A lot of times what we see is that heart rate is the manifestation of these other types of stressors. So you’re cognitively stressed out and your body starts to respond by raising its heart rate. It’s a fight or flight type of response.
Bernie Fette (15:15):
Mike Manser (15:16):
When you’re under stress, certain things can happen cognitively as well. So you might be under a cognitive stressor, like it’s a really busy environment. If you’re approaching an intersection, there’s pedestrians and bicyclists and there’s lots of stuff going on mentally. So you’re paying attention to it, that cognitive stress goes up. As a result, your heart rate starts to go up as well, in response to that. The challenge when you’re under high stress situations is that your attentional focus can become diminished. So you’re not as capable of picking up the important cues in the environment. So you can imagine that intersection scenario I just mentioned. You’re approaching, there’s lots of bikes and cars, your stress goes up. Unfortunately, one of the poor byproducts is that your ability to focus on all the important cues in the environment tends to shut down. So you start to miss, for example, the biker who’s just about to pull out in front of you, you may start to miss the pedestrian who’s just starting to cross the street. And that’s really one of the most nefarious things that happens here. Your stress level goes up in response to a stressful situation. And unfortunately that begins to affect other processes that are happening that make the impact of that stress even more dangerous.
Bernie Fette (16:38):
So clearly there are safety implications here.
Mike Manser (16:42):
Yes, absolutely. Yes.
Bernie Fette (16:45):
Does this level of stress, you mentioned cognitive stress, let’s call it just for the moment, brain stress, thinking stress. Are there instances in which that can actually mimic an impairment for driving in much the same way that we understand impaired driving in other ways?
Mike Manser (17:05):
Yeah, in, in some ways it is an impairment — differently than say, traditional types of impairment like alcohol, drugs.
Bernie Fette (17:13):
Mike Manser (17:13):
But stress can reduce your ability to adequately and appropriately respond to a situation. And in that way, yes, it is an impairment. It does cause the decrement in your ability to deal with these driving scenarios.
Ioannis Pavlidis (17:29):
Just to follow up on Mike’s point, this is the state of being absent-minded, right? That you drive, but your mind is somewhere else. Everything else is in place. I mean, your hands is are on the steering wheel and your eyes, uh, look in front of you. So you’re not doing, uh, something apparently bad like texting and driving. But this is still a distraction because your mind is not on the task. So you, you still have multitasking. Therefore you’re trying to do too much. That means that the stress response kicks in. One of the ways a stress response manifests itself, which many people don’t know, is you start having increased tremors.
Bernie Fette (18:15):
So your hands are shaking.
Ioannis Pavlidis (18:17):
Yes. And they’re not visibly shaking. I mean, probably from your own experience, when you’re totally upset, you feel shaking, right? This is the extreme manifestation of this, but there is a continuum. I mean, as you get more and more stressed, there is more and more of this shaking, which up to a point is not even visible, but it’s there, right? Mm-hmm. <affirmative>.
Bernie Fette (18:41):
Ioannis Pavlidis (18:42):
So, this is shaking. Basically what it does, it transmits into the handling of your steering wheel. So instead of keeping it totally steady, you start moving it a little bit to the left, a little bit to the right, and automatically you counter balance. But you know, at 60 miles per hour, such a little tremor if it is left uncorrected may land you a little bit on the left or right lane, and there you have your crash. So there are all these insidious ways we found in previous studies. That things that are not apparent, like absent-mindedness, can get you potentially into trouble under certain conditions.
Bernie Fette (19:25):
If we could, maybe we can step back and look at some of this just a little more broadly for a moment. Do you have any reason to believe that driving-related stress has become worse in recent years?
Ioannis Pavlidis (19:40):
The answer is yes, but unfortunately we did not measure this exactly in this particular study. There have been other studies, and Mike can speak more about this to our knowledge none that is naturalistic. I mean none that like the one that we did. I mean, in our study there were no instruments. We were getting data from the Apple Watch and the iPhones of the people. We did not give them anything actually, right? And we were collecting data because these things emit the GPS. But we were going on the internet and from open data sources, we were finding out at every point of their itinerary how much was the traffic. Mm-hmm. <affirmative>, the weather was there at that point in time, and we were building the entire picture around them. Moment by moment, these type of studies, I don’t think they have happened about all these big stressors, right? Mm-hmm. <affirmative>. So they have happened something in the lab, which is totally different thing, but to the best of my knowledge, there are very few, if any, studies that study all these big stressors moment by moment in a naturalistic setting. Much like we did.
Mike Manser (20:55):
As Ioannis said, we measured stress in very short timeframes. So we were actually just looking at stress on a day-to-day basis. Across a, a single week of that data collection period for a participant. But the question is whether stress in driving is getting worse over the long term, like so over the last several years or decades. And I don’t know if studies that have looked at that exactly, but what we do see is, for example, the incidents of distracted driving. Distraction is an example of a cognitive stressor, right? You’re looking at something and you’re trying to dial your phone or you’re trying to talk to your kids in the backseat or something. We do know that the incidents of distractions and driving has grown significantly. We also see the incidents of things like road rage has also grown over the last number of years. So we do think that stress in driving has been increasing over the last, say, several decades. I don’t know that anybody has measured that specifically because long-term studies like that are really hard to conduct and they tend to cost quite a bit of money. So the, the emphasis tends to be on shorter term studies. But anecdotally, I would say yes, that stress is increasing in driving and over the last many years, that has continued to get worse and worse and worse for us.
Bernie Fette (22:22):
And why do you think that is? You did mention cell phones and trying to do too many things, or going back to the notion of brain stress overworking your brain. Are there any other indicators that you’re aware of? Other than that?
Mike Manser (22:36):
Cell phones are definitely one major class of distraction or mental workload or a stressor that is placed on somebody. But we have to look at this issue of stress in its totality. There are lots of other stressors that go on around us. For example, you know, like traffic density, if it’s really dense traffic conditions, you have to pay attention to a much greater degree of what’s going on. So there are lots of cars around you. You’re having to pay attention to who’s cutting in and who may cut in, who’s slowing down, who’s speeding up compared to more open driving, you know, like if you’re in a rural road where you don’t have as much of that to attend to. So your stress may not be quite as high. In the work that we were doing, we found that speed was a big factor. And that makes sense because as you travel faster, you have to attend to more stimuli basically to be able to drive just as safe as you were at lower speed. So now you have to pay attention to other cars that may pull in. You have to pay attention to where you are in the lane and where you are relative to a lead vehicle. So those stressors in higher speed scenarios become more important and more prominent. So we do see stress go up in that particular case. So yes, there are lots of indicators of stress and we try to measure this in our work and we just mainly look at one of the main indicators of stress, which is heart rate.
Bernie Fette (24:05):
One other thing that definitely seems to have changed over recent years is how the youngest drivers among us might look at these things. And I ask that because I was reading recently in a story in Parents magazine about how only about 25 percent of 16-year-olds had a driver license in 2014 compared to almost half of all 16-year-olds, just 20 years earlier. So a lot of young people who are choosing not to drive, and they say the reason is that they’re too nervous — that about one fourth of the teens who were surveyed said that they don’t have a driver’s license because of their fear of driving. Is it reasonable to draw a connection here?
Ioannis Pavlidis (24:53):
It is, and actually we have proof for that. It’s a study that Mike and I are working right now, which we have not published yet.
Bernie Fette (25:01):
Ioannis Pavlidis (25:02):
And the analysis so far shows exactly what you said about the young people. And actually in a question, if there were automated cars today, I mean fully automated, would you let the car drive all the time or would you let it drive some of the time? Or would you not let it drive at all? And you would do all the driving yourself. And people in their forties and fifties and so forth, in the great majority say, I would do all the driving myself. And you see the young drivers in their twenties, the great majority says that I will leave the automated car drive all the time. I think that more than anything else shows the divide between the two generations, the way you touched upon it. Mm-hmm. <affirmative>
Bernie Fette (25:53):
Ioannis, I’ll let you know that whenever I first contacted Mike about doing this episode, I was remembering how driving used to be in many cases and in many places, something that we did for pleasure. And Mike mentioned actually just earlier in our conversation today, uh, that the idea of a Sunday drive, and I remember the Sunday drives I used to go on with my parents in our 1955 DeSoto station wagon. It was an excursion on the open roads meant for nothing other than pleasure. The destination really didn’t matter. It was all about the cruising. So my question for both of you is, are those days gone forever?
Ioannis Pavlidis (26:34):
<laugh> Gone forever? Maybe not entirely, because even in this study, if you read the paper, we found out that over the weekends, on average, people have much less stress when they drive. Mm-hmm. <affirmative> versus the weekdays. So there is still something left from the old days, but <laugh> …
Mike Manser (26:54):
I have to agree with you, Ioannis. I don’t think the days of enjoying driving are then and gone <laugh>, but I think they’re waning. Definitely.
Bernie Fette (27:04):
Last question. What is it that motivates you to show up for work every day? You can flip a coin on who goes first with whoever would like.
Ioannis Pavlidis (27:14):
To me, it’s basically what I’m doing because I’m, in essence, I’m studying human behavior. So every day I find more and more how fascinating animals humans are. <laugh>, for example, I take is a study, right? And you are always surprised you, you find the best possible conditions and you get something that you did not expect. And there is unexpectedness is to me, what is make it, uh, worthwhile.
Mike Manser (27:43):
For me, what makes it worthwhile is the potential to make driving safer for people. We look at science oftentimes as each individual study is a little brick that begins to build a bigger wall. And that wall represents sort of the truth or the final information portfolio that can be used by people like manufacturers or designers in companies that can design technology or vehicles. It can be used by policy experts to set new laws and stuff. And for me, what really gets me motivated is just you do these studies and we’re putting together, you know, these little tiny bricks, but they’re really important bricks for seeing that bigger picture and research and the, just the idea that, you know, once you get enough of these things in place, it can really be beneficial for a whole host of safety stakeholders. But ultimately it’s that potential to help people, help save lives.
Bernie Fette (28:43):
Well said. We have been visiting with Mike Manser, a Senior Research Scientist at TTI and Ioannis Pavlidis, who is the Eckhard-Pfeiffer Distinguished Professor of Computer Science at the University of Houston. Gentlemen, thank you both for sharing your insights. We really appreciate you taking the time.
Ioannis Pavlidis (29:05):
Thank you. Thank you very much.
Mike Manser (29:07):
Thank you, Bernie.
Bernie Fette (29:09):
Some of us might remember the concept of a Sunday drive. An excursion on the open roads meant for nothing other than pleasure. The destination didn’t matter. It was all about the journey, just cruising purely for enjoyment. More often than not today, however, we might feel lucky if a typical drive isn’t profoundly stressful. Whether the stress comes from something obvious or something that’s more difficult to detect and measure, the anxiety we feel isn’t just making the drive unpleasant, it’s also making it unsafe. Thanks for listening. Please take just a minute to give us a review and subscribe and share this episode. And please join us next time for a conversation with Jason Crawford, to hear about how problem-solving research makes its way from the lab to real-life transportation environments in cities across Texas. Thinking Transportation is a production of the Texas A&M Transportation Institute, a member of the Texas A&M University System. The show is edited and produced by Chris Pourteau. I’m your writer and host, Bernie Fette. Thanks again for joining us. We’ll see you next time.