Issue 9: August 2019

Senses and Sensors

This issue of The Caltech Effect features scientists and engineers whose research helps us better understand how we sense and make sense of the world.

Illustrated Story

How to Build a Space Telescope

The year was 2012. A small NASA telescope named NuSTAR launched on a rocket. When it reached space, its tightly folded mast stretched out to 33 feet, and two very new eyes started to record the light that reached them.

Story + Animations

Listening with Light

Caltech’s Zhongwen Zhan has a vision for the next generation of earthquake-monitoring networks: the use of lasers to assemble the most detailed picture yet of how the earth vibrates.


The AV Rabbit

Multisensory perceptual illusions are surprising and fun, and they also provide insight into neural processing in the brain. The AV Rabbit, Caltech’s most-viewed video of 2018, reveals that an auditory stimulus can retroactively affect your visual perception.

Noelle Stiles (PhD ’15), then a visitor in biology and biological engineering, led the design of this illusion, with contributions from Shinsuke Shimojo, the Gertrude Baltimore Professor of Experimental Psychology and an affiliated faculty member of the Tianqiao and Chrissy Chen Institute for Neuroscience at Caltech, along with former Caltech postdoc Yukiyasu Kamitani (PhD ’01), Carmel Levitan of Occidental College, Monica Li (BS ’16), Ishani Ganguly (class of 2020), and Armand Tanguay (BS ’71) of USC.

Read the story that accompanied the video’s original release in 2018.


Sensors and Sensibilities

Like any scientist, Noelle Davis has an eye for detail. But this rising senior from Fort Worth, Texas, brings unusual focus to the visual world.

Points of View

Five Researchers on Sensing

We asked members of the Caltech community to explain how sensing and sensors inspire their research.

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The Sensory Passageway for Nicotine Addiction

In Dennis Dougherty’s lab, we study receptors in the brain that are drug targets for treating a variety of health conditions and disorders. A receptor functions as a means for two neurons to communicate when it is activated by specific chemicals that nature designed it to detect. I create amino acids that are not found in nature and use them to subtly change the nicotinic receptor nAChr, and I also make tiny changes to a chemical that it detects. My objective is to learn how cytisine, a smoking cessation drug, activates this receptor. To use an analogy, I make precise alterations to a key (cytisine) and a lock (nAChr), all to better understand nicotine addiction.

Annet Blom (PhD ’19), former llene and Howard Marshall Fellow

The Sensitivity of Pectin

My adviser, Chiara Daraio, was combining plant cells with carbon nanotubes to create synthetic wood when she noticed the new material was responsive to temperature changes. Her curiosity led her to discover that pectin, an organic polymer found in wood and other plant cell walls, when dehydrated, outperforms the best thermal sensors on the market. Today, we continue to improve the stability and sensitivity of pectin. We aim to create inexpensive, flexible, temperature-sensing films that could be used, for example, in health-monitoring devices, car batteries, and electronics. Also, from our many experiments, I am developing computational and theoretical models to systematically explain pectin’s electrical properties.

Linghui Wang, graduate student in applied physics

How a Drone "Sees"

As a SURF student in Soon-Jo Chung’s aerospace robotics lab, I helped test a sensor that could be used on an autonomous flying ambulance drone. The sensor, an IMU (inertial measurement unit), measures linear acceleration and angular velocity. Now, on a team led by Joel Burdick, I am building on what I learned to help design a tunnel-traversing drone for the DARPA Subterranean Challenge. The drone computes its position and plans its path using IMUs in combination with other instruments, including LIDAR (light detection and ranging), which measures the distance between the drone and obstacles, and a visualization system with high-definition cameras that feed into a flight controller. Sensors plus robust algorithms: Together, these are how we enable a drone to navigate and “see.”

Anuj Chadha, Robert J. Kieckhefer, Jr. Memorial Scholarship recipient

Making Sense of Survival

We simulate naturalistic conditions for mice and observe responses necessary for survival. For example, predator avoidance: A dark expanding disk shown on an overhead monitor elicits fleeing or freezing because mice sense an approaching aerial predator. Or prey capture: Despite differences in the time each mouse requires to learn how to capture an insect, it always takes just one successful hunt for a mouse to become an efficient hunter. With two faculty advisers, Markus Meister and David Anderson (both from the Tianqiao and Chrissy Chen Institute for Neuroscience at Caltech), I study these behaviors and the involvement of evolutionarily conserved, relatively ancient subcortical structures of the brain. We want to understand these instinctive reactions and where that information is transformed into a successful motor output.

Zeynep Turan, graduate student in neurobiology

What Creates Our Moral Sense?

Philosophers have long suspected that humans possess a unique faculty of perception dubbed “the moral sense,” which you can think of as an evolved capacity to perceive and react to morally significant events. In the Caltech Brain Imaging Center (part of the Tianqiao and Chrissy Chen Institute for Neuroscience at Caltech), my laboratory studies how this sense arises by peering inside the brains of people making difficult moral decisions, such as how to distribute scarce food resources among orphans. We find that how fairly people distribute these resources depends on how emotionally averse they are to inequity, and this is reflected in differences in brain activity. Our sense of fairness, viewed by philosophers as humans’ most complex capacity, is deeply rooted in the brain’s machinery.

Steven Quartz, Professor of Philosophy