We live in the present. We know the experiences that have occured in the past and we expect to have fun times in the future. We can feel the passage of time and it passes fast or slow depending on the situation or our emotions. How is it that we can feel the passage of time? This is a big question that has been asked for a long time. Science, including brain neuroscience, is trying to clarify the mechanisms of “mental time travel”.

We refer to the awareness of time, over the past, present, and future, as “mental time”. Mental time is a cognitive function that has evolved in humans in particular. There are three examples that provide evidence of this: 1) We ask a person what’s today’s date when diagnosing dementia. The awareness of the date is essential for humans, but not for other animals. 2) Most languages have exact tenses. This provides clear evidence that we are always aware of the past, present, and future. 3) We are afraid of death, the end of our future. Chimpanzees, by contrast, do not show signs of fear of the future, even when they have been severely disabled.

Where does mental time, the human-specific awareness of time, come from? In this Research Topic, we aim to construct a new research area, “the science of the mental time”, through active collaboration with neuroscientists, cognitive scientists, psychologists, clinical neurologists, linguists, philosophers, and comparative ethologists. We would like science of mental time to be included in studies of brain mechanisms.

Keywords: mental time, interval timing, temporal cognition, temporal illusions, brain mechanisms

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