Scientists Discover a “Shy” Plant That Can Count Without a Brain, and It May Be Smarter Than We Thought

A groundbreaking study by William & Mary psychology professor Peter Vishton and his former student Paige Bartosh has revealed that plants can exhibit cognitive-like behavior without a nervous system. The researchers worked with Mimosa pudica, a plant commonly known as the shy plant or touch-me-not, and found that its leaf movements were influenced by the number of light-and-dark cycles it had experienced. Published in the journal Cognitive Science in late 2025, the study presents the first evidence that plants can enumerate, or distinguish and track discrete events in their environment. This capacity was previously thought to require a nervous system. The researchers discovered that the plants adjusted their movement patterns to anticipate the arrival of light, even when the timing was irregular. Inside a windowless room at William & Mary’s Integrated Science Center, Vishton and Bartosh built a humid tent and exposed the plants to a repeating three-day cycle. On the first two days, the plants received 12 hours of light and 12 hours of darkness, while on the third day, the lights stayed off entirely. After roughly five repetitions of this cycle, the plants began moving more during the dark hours just before light was expected, but only on the days when light was actually coming. The learning curve of the plants matched a well-established pattern from animal studies, with a rapid initial adjustment followed by a gradual increase in their ability to predict the pattern. The researchers also found that the plants were not simply following a circadian rhythm, as they adjusted their movement patterns to a new schedule when the day length was shortened from 24 hours to 20 hours. The study’s findings suggest that plants can track the number of events that take place, rather than simply responding to time. The researchers believe that this ability is mediated by structures called pulvini, which contain motor cells that regulate movement through rapid shifts in turgor pressure. No neurons are involved in this process. The study raises questions about the role of non-neuronal cells in animals and humans, and whether they might be more capable than assumed. Vishton noted that there are lots of cells in animals and humans that aren’t neurons, and we just assume they’re not involved in learning. But maybe they could be. The authors are careful about the study’s scope, acknowledging that higher variability was present in some results and calling for replication with additional controls before the findings can be considered settled. Potential applications of the study include plant-based sensors, biologically derived computational devices, and research into how cellular-level learning might relate to habit formation and unlearning in humans. As Vishton said, the mechanistic questions fall to chemists and biologists. His role was to characterize the behavior, and he hopes that the chemists and biologists of this world can ask more mechanistic questions to understand how this is actually happening.