This is a concept from the Power of Now which is quite astonishing. I have always had difficulty with Time Keeping because my Perception of Time is practically non existent. I have had to learn Clock Time for pragmatic purposes so that I can catch a train, attend an interview etc. Clock Time is the normal passing of time that is accounted for by all of our horological devices eg Rolex watch etc. I love it when I can insert a bit of everything comes from the Greek;)
Psychological Time on the other hand is completely different. This can be any length of time as it refers to the duration of an idea, emotion and any of those other ethereal things which are of unknown length. They can be good or they can be bad although Eckhart believes them all to be bad to the point of being a disease. I think it depends on what caused you to leave the present to indulge in either the past or future. It may help you to think of it like when you enter the fictional realm of Narnia in the stories by CS Lewis. Narnian time runs much faster than in normality but you are unaware of it as you are completely absorbed in this new world. It’s only when you return through the wardrobe that you realise no time at all has passed yet for you it feels like an eternity because of the experiences you have had. For a moreup to date version you can substitute quantum time as demonstrated in the Antman and Wasp Marvel movie series however here Time stretches out to infinity much like in the Inception movie.
In the Power of Now Eckhart Tolle says that in order to be the best version of our selves we need to utilise Clock Time in order to complete the practical elements of our lives. We have to give these tasks our full attention but be able to leave them alone when they are done otherwise they will take over our attention and become Psychological Time. When we are distracted thinking of things still to be done we cannot focus on anything else as our minds are focused on the future. We have lost the Now since we are in a different timeframe in our heads.