Our experience of the present is constructed through the recent past: this what a new study by the group of Mathew Diamond at SISSA, published in Nature Communications, demonstrates. The researchers have worked out the algorithms the brain employs to shape each new tactile sensation, as a function of the stimuli that have been presented earlier. The study’s main result is quite simple, according to Diamond: “As we perceive the world, our history of experience creates a context for understanding the present.”
The Diamond team, which includes Iacopo Hachen, Sebastian Reinartz, Romain Brasselet, and Alisea Stroligo, first observed the phenomenon in rats, and then found that the exact same algorithms are at work in humans. The team investigated the influence of the intensity of preceding stimuli on the perception of the current stimulus. They discovered that the strength of a brief vibration, delivered either on the subjects’ fingertips (in humans) or on the whiskers (in rats), determined how subsequent vibrations were judged. Based on these observations, the authors created a mathematical model that predicts how “strong” or “weak” one vibration will be perceived according to the individual’s recent sensory history.