She added: "I think most of us have had the experience of rushing around or being immersed in thought - it feels like a long period of time, and we're surprised to find out how much we did, physically or mentally, in only a few hours.
"If it was a day where not much happened you may think 'where did the day go, I did nothing!' Alternatively, maybe you had a very busy day. You may think 'wow today felt like four days of work!' "
Sensory areas of the brain
For the new study, researchers asked 40 volunteers to watch video clips of either a dull office environment or a vibrant street scene while recording activity in sensory areas of the brain.
The participants were then asked to judge how long each clip lasted.
Scientists found that the street scene clips were judged to be 5 per cent longer than they actually were, while the tedious office scenes were perceived to be shorter.
When they looked at the brain they saw large changes in brain activity in the visual areas when the bus street scenes were being viewed. When more changes were recorded, the participants felt the videos had lasted for longer.
It suggests that the brain's basis for experiencing time is based on how much activity is being perceived by the senses, rather than working like a simple clock, measuring the minutes ticking over.
Senior author Dr Warrick Roseboom, of Sussex, added: "This new work is an important step in deepening our understanding of the basis of time experience in the human brain - extending our previous theoretical work by directly looking at brain activity and how people feel about time while they watch videos of natural, everyday situations."
The team has recently embarked on the world's largest study into how people's perception differs.
Participants taking part in the Perception Census will be invited to complete a series of tasks, exploring themes such as colours and illusions, time, sound and music, and beliefs about the world.
Perceptual experiences
Researchers are hoping to answer questions such as "How do our brain's 'expectations' affect what we see?", "How vivid are our imaginations?", "How do our senses work together?" and "How do we sense the passing of time?" to find out how people individually encounter the world.
Anil Seth, professor of cognitive and computational neuroscience at Sussex, said: "By exploring many different aspects of perception together, we'll be able for the first time to understand how these different ways of experiencing the world relate to each other, giving each of us our own, totally unique, 'inner universe'.
"This uniqueness can be hard to appreciate, because - unlike differences in our bodies - our perceptual experiences are internal and subjective, and this variety remains largely hidden.
"Just like our externally visible differences, when it comes to perception there's no 'good', 'bad', 'better' or 'worse' - there's just diversity, and in this diversity lies a rich potential to understand ourselves and each other much better."
The research was published in the journal PLOS Computational Biology.
