Questions on Perception


Dear Professor,

Your article on the net titled "Perception and Reality" is indeed very enlightening. However, after reading through it, some questions/comments have sprung up in my mind which i would like to share with you :
Q1) " If our brain perceives only the electrical signals of the stimulusand does not come into contact with the stimulus itself, then does the stimulus actually exist, can we be sure of that ?"
Q2) Is it possible that these electrical signals could be coming from
some artificial source ?
Q3) Does the universe actually exist or is it just our perception(just like in a dream) i.e. Are we beguiled by deception that there is a world outside the brain?
Q4) What about the brain, can it also be itself, just a perception. If that is a possibility, then who is this thing that is going through all these perceptions ?

Would greatly appreciate your response on the above.

Kashif Shirazi
Karachi, Pakistan


Dear Mr. Kashif Shirazi:

First of all let me tell you I feel honored to know that my article
"Perception and Reality" has been read by a distinguished person from such a distant country. I also thank you for your intriguing questions.But, initially let us clarify an important point: we do not "perceive only electrical signals of the stimulus" Actually, what we do perceive are electromagnetic waves, not as waves, but as images and colors; vibrations,not as such, but as sounds; chemical reactions, not as such, but as specific smells and tastes. Because receptors of sensitive neurons located in our sensorial apparatus allow us to do so. Then, these receptors convert the physical expression of the stimulus (light, sound, smell etc...) into action
potentials which transform them into electric signals that conduct the sensorial message to specific processing areas inside the brain. Thus,electrical signs are not related to the initial phase of perception, as you mention on your first and second questions, but of subsequent stages of the process. Hoping this is now clarified, let us try to answer the specific questions you have formulated
1)  Yes, the stimulus actually exists. Otherwise, how could it be perceived by our senses ?
2)  Yes. Mostly, we receive stimulus from natural sources, that surround us,like the smell of a food, or from a distance, like the sun rays. But the stimulus may also come from an artificial source,  like an image transmitted by a satellite.
3)  Yes, I believe the universe does exist. However I am not sure we
recognize our universe as it really is, since we can only perceive it
through the specific sensorial apparatus we have been provide by evolution. Let us take color as an example. We, humans, can perceive several colors,within a spectrum which ranges from red to violet. The dog, however, seems to see everything only as gray. And even among us, some daltonic people, may not distinguish colors as they are perceived by non-daltonic individuals. And similar differences may occur regarding other senses. Therefore, each species must have a particular conception of the universe.
4)  This remarkable question of yours is, in some way, related to the third one, since both seem to favor illusion instead of reality.
They bring to my mind the theory of "Radical Idealism" proposed by Berkeley,an Anglican Bishop, for whom nothing can be said with certainty about the universe, because it may be only a fantasy, an illusion created by our minds. By the way, this subject makes me recall an extraordinary "game of words", that, supposedly, took place between the spiritualist and idealist Berkelely and the famous scientist and convicted materialist David Hume:Hume said: There is no mind?  It does not matter.Berkeley answered: There is no matter ? It does not mind Back to your question: perhaps I could accept that the universe and the brain are just perceptions, illusions, nothing else.
Yes, I could. But I do not. I do believe that the universe exists and that the brain is not a perception, but a concrete organ, capable of  having perceptions. However, if I am wrong, then, perhaps, we could regard ourselves and,consequently, our brains, as well as the whole universe we live in, as being just a dream (or a nightmare?) dreamed by a superior conscience - God ?
But, by God, I feel I am not wrong !
Hopping my scientific and also philosophical remarks have satisfied your highly philosophical questionings and doubts,I remain.

Yours sincerely
Jorge Martins de Oliveira



Copyright Silvia Helena Cardoso, PhD