Memory is a key part of the mystery that is human consciousness. In many ways, consciousness is memory. Your consciousness is constantly evolving, based on the experiences you remember.
Though consciousness is more than just memory because you don’t remember everything, and your memories are not always true. People often warp memories in their minds, for better or worse. If consciousness is what you remember—the things you keep in your “conscious” memory—then really, consciousness is equally formed by what you forget. Human consciousness would be unrecognizable without the ability to edit and omit memory.
Where does that ability come from? Consciousness likely results from all the genetic code embedded in DNA that helped in human evolution—the ability to socialize, bond, and communicate with fellow humans in a tribe and to cooperate in large groups. Consciousness was a massive advantage in promoting cooperation—being able to think of what another human is thinking, to remember (and forget), and to lie. Lying is essential to group survival because being able to tell white lies promotes cooperation.
Furthermore, without lying, language itself wouldn’t exist. Language is inherently a lie—inventing a word or phrase to label something in the physical world (or a concept in the imagination). An apple is not an “apple.” Those are just letters and sounds humans created to refer to a red fruit that grows on trees. (Just as “red,” “fruit,” and “trees” were invented as well.) All of language is ultimately a form of lying, in that it is only ever an approximate representation of reality, not the real thing.
Beyond the metaphysical semantics, imagine if you could only tell the truth—always—just blurt out your initial gut instincts all the time. It wouldn’t go very well. You’d probably have everyone hate you, or worse, be in prison for sexual harassment, death threats, or a million other horrible things that pop into your head but you (usually) never act on. Imagine telling the opposite sex exactly what you feel when you see them (whether you are attracted to them or not, either could be equally offensive).
That’s just one example. What if a friend asks what you think of their new clothes or hairdo? People need to be able to tell white lies in order to have anyone like them. Likewise people need to be able to forget. Those who can’t forget are often depressed—too focused on sad memories.
Consciousness is really a filter of memory. It is formed by what your brain chooses to remember, and how you frame those memories through your subjective perception. In this sense, you can change your consciousness by acquiring new knowledge to reframe your memories. Forget that which is no longer relevant. Form a new filter for reality.
Human consciousness is the brain acquiring data (memories) framing that data subjectively (lying) and deleting useless information (forgetting).