According to our subjective experience, the time will be long and short. A recent study explains why. Our sense of time may be the basis of all our experiences and actions, but it is an unstable and subjective feeling that expands and contracts like an accordion. Emotions, music, events in our surroundings, and shifts in attention all speed up or slow down our sense of time. < / P > < p > when we see the pictures on the screen, we feel that angry faces are longer than expressionless faces, spiders are longer than butterflies, and red ones are longer than blue ones. Seeing the boiling water in the pot, it seems that the water doesn’t boil; and when I’m happy, time flies. In the journal Nature Neuroscience last month, three researchers from the Weizmann Institute of Science in Israel presented some important new insights into the factors that affect our sense of time. They found evidence that there is a link between a sense of time and the mechanisms that help us learn through rewards and punishments. They also show that our perception of time is closely related to our brain’s constantly updated expectations of what will happen next. “You know, ‘time flies when you’re happy,'” says Sam Gershman, a cognitive neuroscientist at Harvard University who was not involved in the study. “But the real reason may be that time flies when you get more happiness than you expect.” < / P > < p > < p > “time” means more than one thing to the brain. Different brain regions rely on different neural mechanisms to track the passage of time, and the mechanisms that govern our experience seem to change from one situation to the next. However, decades of research have shown that the neurotransmitter dopamine plays a crucial role in how we perceive time. Dopamine has countless effects on our perception of the time that has passed in a given period of time, and these effects can be confusing. Some studies have found that the increase of dopamine can accelerate the internal clock of animals, leading to animals overestimating the passage of time; other studies have found that dopamine compresses events, making them appear shorter; and others believe that, according to the specific situation, both effects exist. The association between dopamine and sense of time is interesting, in part because the neurotransmitter is known for its function in rewarding and reinforcing learning. For example, when we get unexpected rewards – that is, when there is a prediction error – we feel an influx of dopamine, which tells us to keep doing this in the future. It is no accident that dopamine is so important to the sense of time and the learning process. Drugs like methamphetamine, as well as neurological diseases like Parkinson’s disease, change both processes, and change dopamine. And learning itself – the relationship between behavior and behavior outcomes – needs to connect one thing to another in a timely manner. However, scientists still don’t know how reinforcement learning and sense of time are combined in the brain and where. On the contrary, “these two fields are traditionally completely independent,” says Martin Weiner, a psychologist at George Mason University. “If the two fields use the same neurotransmitter system, no one asks,” how reinforcement learning affects timing, “or” how time affects reinforcement learning. ” < / P > < p > the authors of this paper, published in the journal Nature Neuroscience, are Edo Toren, Christopher arbor and Ronnie Paz. Participants in the study would see two numbers flashing on the screen, usually a zero followed by a zero. The second number is shown in varying lengths of time. Participants were asked which number lasted longer. But sometimes, after the first zero, a positive integer or negative integer will appear on the screen instead of another zero: if it is a positive integer, the participant will get a cash reward; if it is a negative integer, the cash will be taken away as a penalty. < p > < p > for the participants, the consequences were consistent with the changes in perception of the duration of the second stimulus. When unexpected but positive things happen – what the researchers call a “positive predictive error,” the stimulus seems to last longer. The unpleasant surprises of negative prediction errors can make the experience seem shorter. “Basically, how surprised we are at the results systematically affects our perception of time,” says Matthew Martel, a psychologist at the University of Villanova. < / P > < p > the research team has proved that this model is quantitative, and the greater the prediction error, the higher the perceived time distortion. The reinforcement learning model they created can predict the performance of each participant in the task. Brain scans of the study participants also tracked the effect in an area called the core-shell. The core-shell region involves motor learning and other functions. < / P > < p > although further experiments are needed to determine the precise mechanisms (and the role of dopamine), this study at least provides some insights into learning models and time perception models. Pavlov’s drooling dog knew that the bell represented food and that the food was in front of him. However, this time component is usually degraded to the periphery of reinforcement learning model. The objective timing of reward is usually integrated into variables, but the subjective aspect of time perception emphasized in the new study is not involved. < / P > < p > it’s time to add some subjectivity. If humans lengthen or shorten their time experience based on signals, it may also change their perception of the distance of certain actions and outcomes – which in turn may affect the speed at which this correlation is recognized. The time effects associated with prediction errors also provide “an additional feature that reinforcement learning models that accurately represent what’s going on in the moment must satisfy,” said Bowen von, a former postdoctoral researcher at Caltech. < / P > < p > “it will be difficult for future modelers, or those trying to deepen their understanding of the brain, to take into account the interaction of the two systems in their research,” matel said. Gershman and his Ph.D. student John Mikhail have been trying to develop a learning model that incorporates these ideas, in which psychological expectations can be improved by adaptively adjusting the flow of time in the brain. However, prediction error is not the only factor that shapes our sense of time. For example, in a study published last week in the journal neuroscience, participants who were repeatedly stimulated for a short time tended to overestimate the duration of a slightly longer interval. According to the researchers, this may be because neurons that respond to shorter durations are tired, which has a greater impact on how neurons that adjust to longer durations perceive subsequent stimuli. (similarly, participants underestimated the duration of slightly shorter intervals after repeated long stimuli.) “By changing the context of stimulus performance, we can actually manipulate the way participants perceive duration,” said Lin Zhengdao, a cognitive neuroscientist at Japan’s information and Communication Research Institute Scans of brain activity show that the right parietal lobe is responsible for this subjective sense of time. Lin Zhengdao’s research focuses on different brain regions and mechanisms, but both studies have observed similar bidirectional effects on time perception. On the one hand, it shows that the timing process in the brain is very fragmented and diverse. But Lin also said that the right parietal lobe does have a functional and anatomical connection with the core shell, so the interaction between the two may produce a more cohesive sense of time. The broad rules and calculations that make these interactions (or others) possible may be the basis of our time experience, but until they are certain, scientists can only look at the clock and feel the passage of time. After 12 years, “world class Super project” Shantou Bay Tunnel ushers in a historic breakthrough today