“Common sense is instinct. Enough of it is genius.”
- George Bernard Shaw
As modern science advances, we continue to get closer to understanding the world around us, and most importantly, how we represent and behave in our environments. However, this process of understanding may be unpleasant at times as we are force to change conceptions of reality that we held true for decades. Cognitive neuroscience is constantly demonstrating to us that the world is not always as we perceive it, that we don’t always remember events exactly as they occurred, and that the pain we feel is not always objectively there. It is as if we lived in a seemingly eternal illusion which we call ‘common sense’ and that once the illusion begins to break apart, we desperately try to amend those erroneous notions. As we understand the dynamisms of our brain, we naturally wonder why we held on so vehemently this ‘common sense’ of the world, a world we assume to be stable and identical to our world. To our surprise, cognitive neuroscience also has the key to such riddles.
Using a framework guided by evolutionary principles and constrained brain design, we start to understand our cognitive and perceptual processes, and also, explain how such ‘common sense’ view had a purpose in masking the illusion of consciousness. It is not simply delusion caused by an utter failure of our reasoning, but instead, an evolutionary byproduct as we optimize for enduring the challenges in our environments. First, brain design had to account for limitations of space while still requiring complex cognitive processes to be carried out. Because of this, our complex environments had to be represented sparsely, and optimally stored. Second, limitations in energy and computation constraints lead to a brain designed to maintain coherence and continuity, while minimizing computation and activation of particular brain structures. In other words, ‘common sense’ had a tremendous role in ensuring our survival. It is not until now that we have the luxury to question why such processes emerged.
It seems reasonable to us that our sensory systems would represent the world reliably (Wall, 1993). However, our first illusion starts in our senses: we don’t see the world the way it is and not all that we see is there. Our visual system was designed to be highly efficient in extracting fine detail under low light and poor contrast conditions with high accuracy and speed, while at the same time representing the world accurately for our efficient navigation and, ultimately, our survival. As Sterling (2003) argues, the system had to minimize wire volume, while maximizing image capacity. Anyone familiar with image and video compression knows well that representing a sparse and yet accurate representation of the external world is computationally complex and difficult. This problem becomes even more challenging as we consider the need of integrating information across multiple sensory systems (Stein, 1998). And while our vision may be optimal when navigating in the forest under dim light, we might be fooled on occasion to perceive intermediate grey areas that don’t exist in the Hermann Grid, to perceive motion from completely stationary but complex patterns, or to fail to notice artificial changes in our environments (change blindness). Our sensory systems have evolved in concert, and not to handle mismatches the way we would expect them to. That is how cross-modality integration may trick us to mislocate the origin of auditory clues based on mismatched visual information (or vice versa). In more pathological conditions, what one perceives may even be father from what the world resembles, such as in conditions of hemispatial neglect, where there is a neglect of one side of the spatial field, accompanied by a strong belief that the world in fact looks how they perceive it. In contrast with ‘common sense’, our visual system was not designed to respond optimally to contrived laboratory conditions, but instead, to survive the challenges in our external world.
Our second illusion consists in believing blindly in our pain and our emotions. Our ‘common sense’ dictates that the experience of pain is a simple process of report of current or prospective damage to our bodies and psyche. However, this is far from true: pain is a highly complex mechanism mediated by numerous factors. First, what we believe to be a cohesive experience of pain has been shown to be two different types of experiences, each associated with the intensity and unpleasantness of the pain (Tulving, 2001). It is also known that pain is perceived after a decision has been made regarding the appropriate biological needs (Wall, 1993). For instance, consider the case of soldiers with severe injuries in the battlefield. Under these circumstances, there is no evolutionary gain from pain and it is not surprising that they exhibit a response-appropriate sensation: 70% of them do not complain of pain upon arriving to the hospital (Beeched, 1859 as quoted in Tulving, 2001). Furthermore, research shows that pain can be regulated under placebo conditions. This complements the view that there is a strong social component to pain, that there are motivational factors are involved, and that pain as we know it has a significant learned component (children do not respond to placebos in the way adults do). As suggested by Professor Finlay at Cornell University, there is also the “pain of altruism”. We feel pain because we know that others can help us (and conversely, we help others in pain because we share their pain, possibly linked neuroanatomically to a special type of neurons called “mirror neurons”).
The findings of cognitive neuroscience extend from feeling pain to broader areas, such as the reports of emotions and internal state. In short, our emotions are highly mediated by our physiological state and our subjective feeling states also have strong social components. Furthermore, interoceptive awareness (which includes the internal representation of the viscera) has been found to be mediated by the insular cortex (Critchley, Wiens, Rotshtein, Oman, & Dolan, 2004), and are thus modulated by all the structures that interact with the insula. Whereas ‘common sense’ may regard reports of internal state (e.g. I feel happy) as subjective and passive reports of the situation, in reality these are known to be mediated by particular structures in a highly active process. These findings strongly suggest that our ‘common sense’ view of pain and emotional state is not necessarily either an accurate nor a passive response to situations in our environment but a multidimensional mechanism.
The final illusion is based on how we remember the world: not all that we remember actually happens and not all that happens is remembered. Closely related to the constraints of the visual system, memory also faces similar challenges such as compression, but has the unique challenges of storage and recall. In contrast with ‘common sense’, our neuroscientist’s understanding of the limitations in memory in terms of capacity explains why we can’t remember everything and the events that we do remember possibly did not occur exactly as we think they did. In cases of amnesia, it’s a well known phenomenon that individuals often confabulate: they create stories about what may have happened or fill the details of incomplete memories. What is surprising is that often these false memories that reveal the individuals’ honest view of a continuous reality (Schnider, 2003). As objective observers, we can corroborate that their memories are just a creation of their imagination (which may often include elements from real events), but nevertheless, they defend these memories vehemently as true. Furthermore, the common belief is that memories are created immediately as events occur. However, cognitive science shows that not all memories are created, and that not all events are recorded as memories, and that if they were the result would be catastrophic. Our memories were designed to satisfy the need for slow and fast storage and recall, which come together neurologically as distinct computational strategies in the brain that respond to different needs (Atallah, Frank, & O'Reilly, 2004). Memory is also an active process mediated by a number of brain structures, and which can be manipulated by factors such as emotional intensity, social interactions. In conclusion, our memories are fallible and ‘common’ of memory do not capture its complex subtleties.
After presenting the evidence of how cognitive science slowly tears apart our ‘common sense’ view, it is natural to evaluate why such a view developed initially. Our representation of our environment does not necessarily follow what we artificially think it should be like. From an evolutionary perspective, I believe that such a view emerged in the process of satisfying the strict constraints while ensuring our survival. The first, the constraint for space power, explains why there is a strong pressure to keep an internal representation that is as sparse as possible, while still useful. Note that ‘useful’ was implicitly defined based on evolutionary fitness and not through a conscious process of rationalization. Our cognition evolved to exploit all redundancies employing heuristics that would decrease the required space and computation while preserving the essence of original information. One of the factors that I believe to be pivotal in ‘common sense’ stems from a design attempt to minimize excess activity in certain pathways that may otherwise interfere with mechanisms that are essential for survival.
Fundamentally, the sentinel that potentially questions our reality —the stability of our external world and the veracity of our internal representation of such world — can easily become the intruder. Monitoring the validity of our interpretations and the correct functioning of our cognitive processes and our bodily processes has potential benefits. However, if such behaviors are carried out regularly, they will hinder our existence. It has been suggested that certain psychological conditions, especially anxiety disorders, may be due to increased attention to autonomic bodily functions (Critchley, Wiens, Rotshtein, Oman, & Dolan, 2004). From a neuroanatomical perspective, our brains optimize for minimal activity and a continuous sentinel would do precisely the opposite. For instance, consider a potential increase in activity in the Anterior Cingulate Cortex and Amygdala arising from responses such as fear from potential mismatch between the world and what we perceive.
Ultimately, the goal of our visual processes, our pain and emotions, and memory may be interpreted as allowing us to learn from the past, and acting appropriately against the challenges in the world. In other words, our brains are likely to have evolved to possess mechanisms that allow the accurate representation of past experiences and perceptions, and the causal attribution of mental states and motivations based on the behavior of others, to consciously (and even unconsciously) guide our future actions and thoughts. ‘Common sense’ might also originate from favoring a more serial nature of the brain, which is far from representing its highly complex and parallel structure. Until now, it may seem that common sense is a collection of static and shared knowledge, but in reality, it is also constantly being redefined and is not as simple as we believe. Decades ago, it was ‘common sense’ that the world was flat and the center of the universe, but with time, that notion started morphing and getting closer to reality. Similarly, ‘common sense’ views of our cognitive processes are slowly being changed. The cognitive neuroscientists’ ‘common sense’ is currently undergoing a process or rewiring, and with time, such amendments will penetrate into general ‘common sense’.
As Higgins & Kruglanski (2004) argue, we value theories that predict what is not obvious, that illuminate failures in our reasoning and that illustrates both the shortcoming and idiosyncrasy of common sense. That is precisely the approach taken in cognitive neuroscience. In the words of Tulving (2001), by initially tackling the ‘axioms’ established by common sense, the process of science can go far beyond it. Cognitive neuroscience continues to pave the road to understand the evolution and purpose of our consciousness. By exploring the nature of common sense, we can begin to understand our cognitive, perceptive, and behavioral processes with far more depth than we ever believed to be possible.