“The great biological role of perception is not to allow us to perceive the world, but, above all, to enable us to act upon it. In other words, we and other species were not selected merely for what we can perceive of the world, but, in fact, for the actions we exert upon it, which have been and are guided by our perceptions.” This was the response that neuroscientist Marcus Vinícius Baldo, a professor and researcher at the University of São Paulo, kindly provided when I asked him about the importance of perception. I believe that, in a few words, he managed to show the fundamental role of this capacity in our lives.
In his article Illusions: the magic eye of perception (Baldo and Haddad, 2003), the researcher defines perception as the active construction of a neural state that correlates with biologically relevant elements of the environment. In common with the interpretation given by neuroscientist Roberto Lent - who defines it as the ability to associate sensory information with memory and cognition, in order to form concepts about the world and about ourselves, and to guide our behavior (see post Our perception is just the tip of the iceberg) - is the fact that this capture of external stimuli is not presented as a passive process, like a static photograph of the environment, but rather as an active process, influenced by internal factors such as memory and cognition.
Looking at the figure below, we see a cube. At first glance, there seems to be nothing unusual about it; however, how is it possible for us to see a three-dimensional image (with height, width, and depth) when what actually appears is a flat, two-dimensional image? This occurs because we have prior knowledge that cubes are three-dimensional shapes, not two-dimensional ones; that is, we have learned that a cube is the geometric shape of objects like a die or a square box. In this way, our brain automatically transforms the flat image (that is presented to us) into an image with one more dimension (what we expect to find).
As we have seen, perception is not a passive representation of the stimulus being presented, but an interpretation and/or reconstruction of it. And besides being modified by our prior knowledge about the world, it is also influenced by sensory systems. When we take into account the differences between species, this influence becomes clear; for example, the spectrum of light that we see or the spectrum of sound waves that we hear is different from that of other animals, which allows the same reality to be perceived differently by different beings.
However, the importance of sensory systems in perception is not defined solely by their physical qualities, but by their ability to trigger more complex mechanisms. For example, odors can make us recall memories with strong emotional content. In fact, a study showed that memories evoked by odor are more emotionally charged than those evoked verbally (Herz and Cupchik, 1995). Thus, we can think that parallel to the capture of environmental stimuli, the senses are also capable of helping to retrieve memories, awaken emotions, and generate associations. There is much to be studied on this topic, and starting from the next post, we will begin to explore it in more detail!
References
Baldo MVC, Haddad H. Illusions: the magic eye of perception. Rev Bras Psiquiatr. 2003; 25(2):6-11;
Herz RS, Cupchik GC. The emotional distinctiveness of odor-evoked memories. Chem Senses. 1995; 20(5):517-28;
Lent R. At the gates of perception. In: One hundred billion neurons – Fundamental concepts of neuroscience (Lent, R). 2010; p. 612-41, Atheneu Publishing;
Figure: http://commons.wikimedia.org/wiki/File:Synthese%2B.svg
