Abstract: The history of eye-movement research extends back at least to 1794, when Charles Darwin’s grandfather, Erasmus Darwin, published “Zoonomia” which included descriptions of eye movements due to self-motion. For the next 200 years eye tracking research was to been confined to the laboratory. That all changed when Michael Land built the first wearable eyetracker at the University of Sussex and published a seminal paper entitled “Where we look when we steer”. Inspired by Land’s work, a group cognitive scientists, computer scientists, computer engineers and geologists have been working to extend knowledge of how we actually use vision in the real world. I was fortunate enough to participate in this ground-breaking experiment earlier this year, and I wanted to share the experience with the geology community! In this blog article I will give a brief summary of the project I was involved in and the things I learned that can really help you be a better field geologist!
How do we look at a scene?
Most animals do not simply gaze at a scene – we simply don’t have the necessary resources to take in every single thing in front of us. Instead, our brains have developed a cunning cheat system whereby we target important aspects of a field of view and build up an image in our mind from the important selected areas. The bandwidth and processing power of our eye-brain circuitry need therefore only deal with a small portion of the image at once, and lots of interpolation can be done at source in the brain. This can be illustrated in the figure below:
Fig.1 Unlike birds, most animals build an image of the field of view before them by targeting important areas sequentially.
Figure 1a shows what a field of view may “look” like to our brain before any fixations are made. Using our limited understanding of this new scene our brain may then target key areas of the field (fig. 1b-c) of view for further investigation. Fixations of varying durations and acquisition order are made, allowing our brain to, in real time, develop a better understanding of what is before the eyes. This process continues and continues the longer we look at a scene.
This process has been proven to be heavily influenced by the individual. The specific way we approach deconstructing this scene depends on a whole host of factors. This could be gender, intelligence, familiarity with the surroundings, experience with the scene, state of mind (distraction, tiredness) -basically any environmental factor that can affect the brain may change the way our brain and eyes go about investigating this scene. We may therefore use eye-tracking to see how different categories of people look at the same scene. To do this, eye-tracking software can gather the following information:
- Fixation Points
- Location, duration, sequence, saccade types
- Pupil Dilation/constriction
Eye tracking technology is therefore a powerful tool in cognitive research that may be used to access the brain. Here are some examples of common applications of eye-tracking:
- Commercial Applications
- User interface design
- Marketing and product placement
- Targeted marketing
- Primate/infant/adult/geriatric research
- Fatigue detection
- Concentration detection
- Sports Training
- Communication tools for disabled people
- Advanced methods for computer-human interaction
- Laser Eye Surgery
- fMRI, MEG, EEG
Eye-tracking is of particular interest to the commercial sector. Interestingly, commercial applications exploit the brain and the eyes: for instance, there’s a proven reason that advertisements at the top of the google search results page cost the most…
So what does this have to do with geology? Well geologists are just one of many communities target by this new research. As mentioned in the abstract, eye tracking technology has only recently become mobile enough to be taken out of the laboratory and into the real world. Geologists are often confronted with new scenes in the field and must use their eyes and brains to really understand what it is that they are looking at. Therefore, by taking amateur and professional geologists into the field and conducting eye-tracking experiments, we can gain insights into differences in ways professionals and novices approach visual problems.
The Study of Geologists in the Field
A joint study between Rochester University and Rochester Institute of Technology (RIT) has for the past five years using a hefty NSF grant ($2m) to research geologists in the field. Principal investigators include Robert Jacobs, Jeff Pelz, and John Tarduno. The beautiful wearable eye-trackers were developed by Jason Babcock. The research has been conducted in a variety of environments, but the part that I took part in was a 10-day field excursion to the Western USA to visit some truly amazing geological localities.
First, lets take a look at the technology that I was wearing for the 10 days, and how it worked:
Backpack – Contains 1 Apple Mac Book Air, the powerhouse of the mobile eye-tracking unit and home to the custom-built processing software.
Head Unit – Contains a front-facing camera above the right eye, and an eye-facing camera and IR bulb for filming eye movements. Also we had to wear a ridiculously large sombrero to shield the cameras from direct sunlight.
Network – All the devices were connected to a local network, the router for which was being carried around here by Jeff Pelz. The custom software meant that he could use his iPhone to get real-time footage from any participants front-facing or eye-facing cameras at any time. This was useful for adjustments and also keeping participants looking where they should during experiments.
The Vans – The network extended back to the vans too. This van was the tech-van and contained massive hard drives for backing up all the data. Each evening, the RIT folk would sit in this van and process/backup the data.
Calibration – Each time we wore the mobile eye-tracking units, we had to complete a series of calibration exercises such that our fixations could be mapped onto the video of our front facing cameras. This was done by standing a few meters away from a calibration spot (as seen below on the back of Tomaso’s notebook) and rolling the head whilst keeping our eyes fixated on the spot. As if we didn’t look stupid enough!
Gigapan Images – Meanwhile, other members of the tech team were taking panoramic GigaPan images of each scene onto which the tracking data could be overlaid.
A typical stop would work something like this (somewhat similar to a roadside execution…):
- On approach to the locality we were told via radio not to look at the surroundings
- We’d get out of the vans, get the trackers on and calibrate
- Someone would then lead us to the viewing point – all the while we had to look down at our feet
- At the viewing point we would be given a question to address in our minds – often something like “What is the evidence this is a tectonically active area?”
- We were then told to look up and analyse the scene in silence for around a minute
- After the allocated time was up we then had to answer questions about what we had observed
- Following questions we would then be given an explanatory guide to the geology by John Tarduno
Unfortunately, I wasn’t allowed to know the conclusions of the study thus far during the trip – this would ruin the experiment. Similarly, if you ever think that you are going to have the chance to take part in a similar study – STOP READING NOW. Despite the lack of information I was privy to, I did manage to get some of the conclusions of the study from the authors before I left. What I am allowed to divulge is pretty intuitive, but may help you and even your students learn to analyse scenes better.
Put simply, professional geologists make fewer, longer and more systematic fixations when looking at scenes of interest. This makes sense – your brain targets the information in a scene that is going to tell you the most useful information to address the problem in mind: i.e. what’s the geological history of this outcrop? Conversely, the students in this experiment made lots and lots of short-lived fixations all over the scene in random places as they tried to search for something they might understand. Here are some visualisations of the differences between students and experts.
The locality above is in Owens Valley, CA (36.60594N, 118.07511W) – fault scarp that resulted from an earthquake in 1872. It is has ca. 15ft of right lateral slip, and 8ft of vertical slip. As you can see from the image above, the expert realises that he/she is faced with a recent fault escarpment. The expert analyses the break in slope and the presence of the boulders on the escarpment. The novice, however, sees no significant feature in the dusty ground and looks to the mountains in the distance and local hills to see if there is anything obvious. The novice’s path of fixations is chaotic and short, returning to the same points briefly for no reason, then heading elsewhere.
The above scene is of a hanging valley located in Yosemite National Park (37.71769N, 119.64846W). The hanging valley represents the valley of a tributary glacier, and is now drainage for water. The cliff face represents the side of the valley calved by the main glacier – this main valley was deeper and so now the tributary valley “hangs”. The expert fixations for this spot are therefore right on the money. The expert looks at the slight u-shape to the hanging valley, acknowledges that there is still drainage here (reinforcing this is in some way a small valley), and the expert also notices the steep valley sides – likely caused by glacial activity. The novice however is distracted by the pretty rainbow and waterfall, and fails to see any real significant features in what to them is just a cliff face.
I had a great time in the USA taking part of the study, and I learned some new and reinforced some old really valuable field skills:
- Make sure you do your research on the geological context of the area – we weren’t allowed to do much reading at all, and it really makes it tough when you are just dumped in a completely new tectonic/geological setting with no warning
- Keep your eyes open all the time – even when driving from spot to spot. You should be gaining information all the time. Not being able to look around as we drove between stops was disconcerting and contributed the the difficulty of interpretation.
- Have a question to answer in your mind – this gives the brain a guide when prioritising fixations
- Make sure you can see properly – sunglasses and hats get distracting direct sunlight out of your eyes
- PUT NOTEPAD AND PENCIL AWAY – just look. Sit there and just look and think. Then when you have understood more, start to draw.
- When you see a feature you think might be interesting, feed it into your starting question: This is a bush… Does the bush give me evidence of recent tectonic activity? No. Stop looking at bushes.
- Relate your stops to other useful resources – maps and satellite images. In the last example, it would be enlightening to see the broad and shallow valley atop the cliff.
- If you find yourself looking all over the place – STOP. Start looking for lines and colour changes – i.e. topography and lithology changes. What are the key features? List them if you need to, even if you don’t understand their relevance.
Remember that your eyes don’t have a brain of their own. They are guided by what you know. If you don’t know anything, your eyes are not much use to you!
Thanks so much for reading! Please feel free to comment below!