How do humans "know"? This is a very difficult question to answer indeed. Let us first approach this from a cognitive perspective. Now there are 6 basic consciousnesses by which we "experience" life. They are: sight, sound, smell, taste, touch and mind itself. The first five corresponds to our basic faculties of sense, but what about the last? Well, without touching, we can imagine touch – that in itself is something that we can “experience”.

In describing the process by which we experience the world, cognitive scientists have come up with two dominant theories: direct perception (or naïve realism), and indirect perception (or representationalism).

Direct Perception	Indirect Perception

Let us approach this using sight as an example, which most would agree is without loss of generality. In direct perception, what you see is the real world, an idea that is intuitive from the days of our childhood. In indirect perception, what you see is not the real world, but a representation of the world. We will never know what the world "is", not even whether it truly exists. What we "see" is an internal representation that may or may not be the "real world". How can we tell which is the "correct" interpretation?

We will now go through some activity to build up our case. Look at the picture below for a while.

Can you see black dots where there are white ones? Are there really black dots? Convince yourself that there really are no black dots by looking at each white dot one by one. By the time you finished looking at each of the 35 white dots, you’d be convinced that there are really no black dots. But why do we see it? The black dots you see are commonly called "after images". Clearly, what you saw was not really "real".

Here is another test. Look at the image below and notice how the red dots appear to move from the left to the right. Note that at every moment there is a red dot, but perhaps in different position. Any gap between a red dot disappearing at one position and appearing at another is so brief that one cannot discern any such gap at all, if it exists. Now cover your right eye with your hand, and focus the attention of your left eye on the plus sign. Even though you’re focusing on the plus sign, you should still be able to "see" the red dot as it is within the visible range of your eye. With your eyes at most half an arm's length away from the screen, do this for about 15 seconds.

Are you surprised to find that there are times when the red dot totally disappears? Did the red dot really disappear? How can you tell? Well you can tell because if you remove your hand and look with both eyes, then you can always see it. This effect is due to what is called a blind spot within our eyes. So we can say that if we cover one eye in the manner as above, what you see is not accurate. But then what makes you so sure that what you see with both eyes are indeed real?

Now look at the cube below. Move your mouse over the orange cover on the left side and the right side. Which cube did you actually see?

Most people would choose the one on the left side. But why? If you look at both cubes, you’d agree that both are possible. Why are people biased towards one of them? The reason is simple – we tend to see cubes in real world context (boxes, tables, cupboards) below the eye level in the same orientation as the cube on the left. Seldom do we see a cube that “peers” upward as the one on the right.

How about the image below. Press the play button and wait as the image changes. By which picture can you tell what the image is?

Why are you able to do so, when the series of picture are actually not an accurate representation of the real thing at all? How was your mind able to “see”?

I’ve reached an important point in which I will now make a claim. And that is – there is no such thing as knowledge, nor such thing as learning by way of transference of knowledge. We “learn” through guessing. That’s right – guessing.

As I have shown, the direct perception theory is obviously flawed. We have seen that the eye, if it was to be interpreted as a tool to perceive the outside world in direct perception, is not an accurate tool at all. The activities we have gone through serve to show that whatever we see are obviously a result of the processing in our brain. There are other convincing reasons to dispute direct perception, most notably the one put forth by Bertrand Russell on the causal chain of perception. While indirect perception also has its problems, what we can conclude is that at least, the direct perception theory is not correct, and there is no way we can tell what really exists, in the "real world".

So everything that we pretend to "know", is actually a guess. But what are the reasons for a particular guess that we make? We shall attempt to answer this in the next article, though some of the activities in this article have already touched on this. For the moment, let's try out the last activity in this article. Look at the diagram below. What words do you see?

Hover your mouse over the covered lower section, and reveal the "answer". What do you think?