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Scientists believe that humans have a hidden sense of touch, called “remote touch,” that extends beyond the nerves in our fingertips.
In new experiments, volunteers detected objects buried in sand without making contact – successfully identifying hidden cubes with about 70 percent accuracy.
The discovery suggests that people can perceive faint pressure ripples in loose materials, much like certain shorebirds that sense prey beneath wet sand.
Researchers compared human performance with a robotic system trained to perform the same task, revealing that human judgment still outperforms machines when reading the subtlest physical signals.
Understanding remote touch
The work was led by Elisabetta Versace, senior lecturer in psychology at Queen Mary University of London. Her research focuses on how brains extract structure from the world using innate and learned rules.
Remote touch builds on the physics of granular media – collections of loose particles such as sand or salt. When you move near a buried object, the grains shift, and tiny pressure changes ripple outward.
Bird biologists described versions of this sense decades ago. A classic study found that red knots detect buried prey by sensing pressure gradients with specialized receptors at the tips of their bills.
Habitat structure can blunt that ability. Experiments showed that roots in seagrass beds obstruct pressure fields, reducing detection performance.
Follow-up avian work suggests that water content matters, too. As moisture rises, wading birds’ remote touch success increases.
Human and robot touch tests
Participants gently raked a single fingertip through a sand-filled box and reported when they sensed a cube without allowing the finger to touch it.
The researchers modeled the signal as grains bounced against a stable surface and sent back faint mechanical reflections.
Human decisions were more accurate than expected. Participants achieved 70.7 percent precision – the share of correct detections among all responses – and detected targets at distances of about 2.7 inches (6.9 centimeters) under these conditions.
A companion setup used a tactile sensor on a UR5 robotic arm trained with Long Short-Term Memory (LSTM), a machine learning method that learns patterns across sequences.
The robot sometimes sensed slightly farther but produced many false positives and finished at about 40 percent precision overall.
This pattern fits the physics bound implied by the sand model. Both systems approached the predicted detection limit, with human hands showing better judgment about when a signal was real.
Real-world uses for remote touch
“It’s the first time that remote touch has been studied in humans and it changes our conception of the perceptual world,” said Elisabetta Versace, the Queen Mary psychologist who designed the human experiments.
The ability to read tiny forces in a shifting medium could make fieldwork safer and more precise.
Engineers have already explored tactile mapping of buried objects. Prior work demonstrates robots that localize objects in dense sand by interpreting contact forces over time.
If moisture boosts signal strength in birds, material-aware tools could adapt search strategies to local conditions. That principle, drawn from avian research, suggests the sensors should tune force, speed, and pass count when sand is wetter.
Archaeology, forensics, and planetary science stand to benefit where vision falters. A refined sense for weak mechanical cues can reduce accidental damage and guide careful excavation in low-visibility settings.
Hidden senses through evolution
While this tactile reach might seem new in humans, evolution has been experimenting with similar sensory extensions for millions of years.
Fish detect vibrations through lateral lines – rows of specialized cells that sense water pressure, helping them move in coordinated schools.
In mammals, whiskers work the same way, translating air currents and texture into touch signals that guide motion in the dark.
Humans, it turns out, may not have lost this capacity completely. The finding hints that our nervous system can still interpret faint physical cues beyond direct contact, even without specialized structures like whiskers or bill sensors.
This suggests that remote touch could represent a dormant human capability rather than a newly evolved one, offering new insight into how deeply tactile processing is embedded in our species.
What scientists will test next
The human results came from a single medium – sand. Replication should probe other common granular media, loose particles like soil or plastic beads, because grain size and friction may reshape the signal.
Distance is only part of the story. Future work should vary finger speed and object shape to map how those factors shift the effective receptive field – the region of space that triggers a sensor to respond.
Better robot training could close the gap. Learning schemes that combine physics based simulations with real trials might reduce false positives and generalize across materials.
There is a human factor too. Training may sharpen the ability to notice weak cues, which could matter for technicians, surgeons, and rescue teams working by touch under pressure.
The study is published in the journal IEEE Xplore.
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