Researchers have found that a soft and tangy water-rich gel can not only play the video game Pong, but get better at it over time.
The findings come almost two years later brain cells in a dish were taught how to play the 1970s classic, a result that the researchers involved said “showed something resembling intelligence”.
The team behind the latest study said that while they were inspired by that work, they were not claiming that their hydrogel was sentient.
“We claim that it has memory, and through that memory it can improve in performance by gaining experience,” said Dr Vincent Strong, the first author of the research, from the University of Reading.
Strong said the work could provide a simpler way to develop algorithms for neural networks—models that underpin AI systems, including Chat GPT—noting that they are currently based on how biological structures work.
Released in 1972Pong was one of the first video games and has a simple premise: two paddles on a court can be moved up and down to hit a ball back and forth between them. The longer the rally, the higher the score.
Strong’s study focused on a single-player version in which a paddle is moved along one wall of a court to bounce a ball.
Writing in the journal Cell Reports Physical Science, he and his colleagues describe how they sandwiched an electroactive polymer hydrogel between two plates, each with a 3×3 array of electrodes connected to a computer system that mimicked Pong.
Six of the electrode pairs, in a 3×2 arrangement, were then stimulated to represent the movement of the ball within the game’s court.
Across the other three electrode pairs – representing the wall next to which the rowing team is located – the team applied a small voltage and the current was measured with sensors. The position of the paddle was defined as the point where the current was highest.
It is important that the type of hydrogel used in the experiment contains charged ions. These move in response to electrical stimulation and linger where they end.
As a result, the point along the “wall” with the highest current can shift as the ball moves, meaning the paddle can change position.
“At the beginning, the ions are distributed evenly and randomly, so the team hits the ball and misses,” Strong said.
But as the ball bounces around the court, the gel gets more and more electrical stimulation.
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“Over time, the ion concentrations increase where the ball is the most, which acts as a kind of muscle memory, as with the higher concentrations there are higher electrical current readings and the scout is able to act more accurately,” Strong said. said.
In other words, the paddle is able to hit the ball more often, resulting in longer rallies.
“Our research shows that even very simple materials can exhibit complex, adaptive behavior typically associated with living systems or sophisticated AI,” said Dr Yoshikatsu Hayashi, another author of the research at the University of Reading.
Dr. Brett Kagan, the chief scientific officer at Cortical Labs, who worked on the Pong-playing brain cells but was not involved in the latest study, said the hydrogel system demonstrates a basic form of memory similar to the way a river bed a memory of the river.
This, he said, could be useful for understanding how changes within a medium can help electrical signals move through it better.
But he said that significantly more work would be needed to show that hydrogels can “learn”.
“The performance and the improvement were linked to a specific place of stimulation. When it was changed in any way, the system could not reorganize to still show performance,” Kagan said.
“This is different from our tests in neural systems where we showed that no matter how you presented the information, learning still occurred.”
