The Now
We humans do not perceive the present as a tiny point on a timeline between past and future, but rather as a period of a few seconds. We refer to this period as present. Within this period of time, our brain continuously builds a holistic model of reality from our sensory perceptions, which we become aware of as the present.
Modeling the present
In order to build up this mental model of our environment and constantly update it, our brain has to do a tremendous job. Light, sound, temperature, smells and tactile sensations have to be put together again and again in the shortest time to form a coherent overall picture.
Even if you only look at individual senses, such as seeing or hearing require extremely complicated processes to take place in the nervous system and brain. Imagine hearing the word “present” spoken by someone. You will then not hear a sequence of individual sounds of the letters p-r-e-s-e-n-t, but your brain will deliver the coherent word “present”. To do this, the sound waves of the individual letters must be heard, identified, put together and differentiated from the previous and the next word. Not to mention the subsequent determination of the meaning of the word.
The brain uses a short-term memory for all of this. This memory last for about 3 seconds and this ultimately determines the amount of time our brain has available to model the present. So the present we perceive is the three seconds that have just passed.
In this picture we see budding, blooming, pollination, ripening and wilting all at the same time in one single wild rose. Symbol of past, present and future:
More challenges
Vision is even more complicated. There is the reception of light waves by two eyes, the pre-processing of the images in the individual eye and the assembly of a spatial image. Of course, this also includes the correct positioning of the image in space, with the brain automatically taking into account the tilt of the head with the help of the sense of balance and the tension of the neck muscles. To do this, information of several senses must be processed in combination. In fact, our brain always includes all senses when modeling the present.
Our brains have to deal with even more difficulties. Many stimuli that affect us from outside do not initially fit together. Light stimuli, for example, reach our brain much earlier than sound.