The conscious experience of any particular thing (or circumstances), is by means of a combination of simultaneous memories being accessed. If the combination involves memories of the conscious object, in addition to the concepts of how that object interacts within its circumstances, the result is a conscious experience of that object. This causes an “aware” connection between the object and its presence.
The complex combination of related and relevant components, is what causes the significant result of consciousness. The inter-workings of a combination of many smaller components, creates something greater and more significant than the sum of its parts. That concept is observed to occur in many other circumstances in this universe (construction by smaller parts), so when considering consciousness, why think otherwise?
The specialty of humans, is the ability to further dissect memories (enabling more specific parts a memory to be referenced), and label memories with language (enabling more effective and precise reference of more memories). These abilities allow access to all the components of memories, which are required to understand the interaction or cause and effect, of that which the person is being conscious of. When a person accesses components of memories, which are relative to the interaction of a particular object, then they obtain a conscious experience of that thing (or things or concept(s)). This combination occurs as brain activity, because the neural activity regularly accesses a memory (coded as neurons), then related memories via commonly used neural pathways. These related memories commonly being accessed, results in the required combination, in the right circumstances.
So, if to be conscious, the required combination of components, is memory of a factor, plus memory of that factors interaction within its circumstances, then;
[Consciousness], = [memory of Factor] + [memory of Interaction of factor].
C = F + I
For eg. Bob is conscious of a squirrel on his lawn.
C = Bob being conscious
F = memory of the squirrel
I = memories of concepts of how that squirrel relates to its circumstances, such as:
the lawn which it is on, it being alive, being an animal, being brown, living on Earth, having a mind, its behavior, its motivations, its senses, the weather elements affecting it, etc.
So, when Bob has memories of the squirrel (F) + relative concepts (I), in his mind, at the same time, this combination of memories = Consciousness (C) of the squirrel.
If, C = self-consciousness
F = yourself
I = concepts relative to your self existence
If, C = General Consciousness (the more generalized feeling or sense of overall consciousness)
F = multiple factors in your current surroundings
I = concepts of how those various factors interact with each other and with additional related concepts
General consciousness feels more significant, because there are multiple factors, and more factors which are significant to the present situation. Whether memories of the factors, or concepts related to the interaction of factors, in general, the amount of memories, causes the amount of consciousness. More Concepts, More Conscious.
Consciousness involving active sensory perception, is more vivid because the factors of which the person is conscious of, are continuously being recorded as memories. With this active sensory input, the memories (of the factor) are continuously, immediately being accessed. The memories being accessed so quickly, causes accuracy and vividity.
From the occurrence of many insignificant, but related components, comes the construction of a few, but significant combinations.