Perceptual Knowledge. An Evolutionary Approach

Perceptual Knowledge. An Evolutionary Approach Marcin Rządeczka Lublin, Poland | marcin.rzadeczka@poczta.umcs.lublin.pl Abstract The nascent field of evolutionary psychology can shed some new light on the concept of perceptual biases. Rather than interpreting a bias as a cognitive flaw, evolutionary psychology seeks to reveal its adaptive function. Systematic distortion of reality can act as a first-line safety mechanism limiting the exposure to potentially lethal abiotic and biotic environmental factors. Several such biases affect vision by influencing the perception of size or geographical slant. The sense of hearing is systematically biased due to the effect of auditory looming, while gustatory and olfactory perception tend to act as a safety measures against environmental toxins and pathogens by oversensitization to bitterness. The variety of adaptive perceptual biases suggests that the prime role of human perception is not truth-seeking, but action-guiding, such as navigation in a dangerous environment or deciding whether to confront a foe or flee. Introduction The reliability of sense perception belongs, without a doubt, to the catalogue of canonical questions pondered by philosophers since at least the time of Parmenides and Heraclitus. The most common view about the purpose of sense-perception assumes it to be a kind of a truthseeking mechanism, a reliable source of knowledge about the external word, and, finally, an important foundation of human cognition. Philosophical debates concerning the reliability of senses seem to be a very diverse field of dispute, yet a slightly more in-depth investigation reveals the common assumption held by the proponents of vastly dissimilar theoretical standpoints. Namely, an assumption that perception serves primarily as a knowledge-acquisition mechanism. However, contemporary evolutionary psychology offers an indubitably different approach. The key assumption is that sense-perception is not a truth-seeker, but an action-guide; formed by natural and sexual selection to be a source of incomplete and highly-biased information about one’s surrounding environment. Biased Doesn’t Mean Non-Adaptive How do we justify the reliability of sensory perception? Historically speaking, the two most popular strategies are based on the concept of an external guarantor of perceptual reliability, which, depending on the further assumption, may be the Cartesian God or the principle of natural selection. However, these two superficially opposing traditions offer, in principle, a very similar solution by making a claim that human sensory perception is overall highly-reliable. In the Cartesian tradition, a genuine sensory-deception, contrary to the mere imperfection of the senses or a source of an environmental noise interfering with the processes of perception, is impossible due to the action of an aforementioned guarantor. A perfect being cannot deceive due to its perfection – the claim which can be inferred from the ontological argument itself. Similarly, the principle of natural selection is often claimed to be a guarantor of perception-reliability, because of the underlying assumption that unreliable sensory perception is simply non-adaptive, and therefore natural selection would have eliminated biasedperception genes from the populational gene-pool. Not to mention the gross over-simplification of the biological evolution, this line of reasoning suffers from a major flaw which results from the assumption that sensory-biases are essentially non-adaptive. Contrary to the above-mentioned view, the nascent field of evolutionary psychology can shed some new light on the reasons behind some wellknown sensory biases and, hopefully, pinpoint their adaptive role as the action-guiding heuristics. The Error Management Theory Undoubtedly, smoke detectors are the first line of defence when it comes to fire prevention, but only when they are fine-tuned to detect even trace amounts of smoke before the fire spreads beyond control. A feature enabling them to precisely discern between rather harmless and potentially dangerous sources of smoke would certainly be very desirable, although when perfection is not an achievable option it is generally advisable to adjust them for higher rather than lower sensitivity. The rationale for this decision is called the principle of asymmetric harm since the potential cost of a false alarm (e.g. cigarette smoke) results in only minor inconveniences and is greatly outweighed by the cost of negligence in the face of a real fire threat. The smoke-detector principle also helps evolutionary psychologists to explain why human beings systematically overestimate the height of a platform they are standing on, the steepness of a hill they are descending or the speed of an approaching sound source. In all these situations, the additional time wasted on being more careful than necessary is a negligible cost in comparison with recklessness resulting in swift death or debilitating injury. Concluding, the principle of asymmetric harm severely limits the evolution of sensory perception by imposing hard-wired perceptual biases with the sole role of an early warning system (Haselton, Nettle, Murray 2016). Auditory Looming Generally speaking, the principle of natural selection tends to cause perception to be more biased whenever more vigilance or swifter reaction to an imminent danger is an adaptive behaviour. The well-studied example of auditory looming accurately illustrates the type of bias in question. Both visual and auditory clues about the speed of a moving object are systematically biased providing a kind of a safety margin, which can be used for a preparation for combat or an instantaneous retreat. Not only our brain interprets the approaching sound sources as faster than the receding ones, but also strengthens the overall effect by underestimating the distance from the sound (Neuhoff 2016). 211 Perceptual Knowledge. An Evolutionary Approach | Marcin Rządeczka The systematic underestimation of distance and overestimation of speed is not a fixed-rate effect, but depends on several other factors, including sex, age, and overall health condition. There is no golden rule in the evolutionary arms race, which is why most perception biases seems to be governed by multifactor context-dependant heuristics. For example, when it comes to age-related effects, the influence of auditory looming is the more evident, as well as when the person in question is physically weaker or lessagile. There is also a strong correlation with the motor system capacity measured with the recovery heart rate, which is a reliable predictor of the total organismal aerobic fitness. In other words, the faster and longer one can run, the weaker is the effect of auditory looming (Neuhoff, Long, Worthington 2012). Systematically Biased Slant Perception Navigating through space can be certainly classified as an action requiring the use of complex heuristics, which, in many instances, also serve as safety measures, counteracting reckless intents potentially resulting in a dangerous fall followed by death or injury. Consistent with this very idea, evolutionary psychologists proposed the concept of the evolved navigation theory (ENT) describing how the human brain biases the perception of height and steepness. While moving on a horizontal plane is usually a safe endeavour which requires a rather accurate estimate of distance, climbing a cliff is affected by the principle of asymmetric harm. After all, falling from a cliff or a tree could easily result in death or at least a major incapacitation. In accordance with the ENT, people tend to overestimate the height of a cliff when they are standing at the top of it, but their height-estimates are roughly correct when they are located at the bottom. The effect was observed in nearly all experiment participants and was decisively significant. On average, the height was estimated to be 1.84 times of its true value (Jackson, Cormack 2007). Moreover, a similar effect affects the perception of steepness. Ascending a steep hill is generally more tiresome, but descending it is definitely more dangerous, which is the reason why the human brain is equipped with the hard-wired tendency to overestimate the steepness of a hill when looking from the top. Once again, other health-related factors can influence the sense-perception, as in the case of the physical fatigue, which may trigger steepness overestimation during the hill ascension (Proffitt, Bhalla, Gossweiler, Midgett 1995). Fear and visual illusions The abiotic environment is not a sole factor influencing human visual perception. Apart from hunting or climbing mishappenings, other important life-threats may result from the actions of other people. Confronting a potentially dangerous human opponent requires a reliable estimate of his size, strength and stamina, which are decisive factors influencing the fight-or-flight response. Once again the error management theory can be applied to predict the presence of a specific bias modulating the perception of an opponent’s size, while in such situations overconfidence is rarely a good survival strategy. In many instances, the visual perception systematically misinterprets the reality to prevent potentially dangerous confrontations. For example, physical incapacitation may influence the perceived and conceptualised size of an angry-looking opponent. The greater the incapacitation the larger and more muscular the foe seems to be (Fessler 2013). The opposite is true when we can find safety in numbers. The presence of 212 comrades creates an illusion that the opponent is substantially smaller and less formidable. The relative safety of a group plays the crucial role of an environmental trigger increasing confidence in the positive outcome of a prospective confrontation (Fessler, Holbrook 2013). However, the presence of children may substantially discourage parents from direct aggression in favour of a more peaceful solution, such as negotiations or a swift retreat. As a rule of thumb, parents tend to overestimate the size and formidability of their opponent in all situations involving their children (Fessler, Holbrook, Pollack, Hahn-Holbrook 2013). The size bias can also be modulated by our cultural experience, such as in the case of a gun influencing the estimated height and muscularity of the foe. A man holding some sort of weapon (the form can be culturally-varied) is perceived to be larger and more formidable than he really is (Fessler 2012). All the above-mentioned effects make human perception very unreliable when it comes to gaining accurate knowledge about the biotic and abiotic environment, which is another argument for the principle of natural selection transforming perception to be an action guiding system able to systematically distort reality for the sake of safety. The Gustatory and Olfactory Perception The principle of asymmetric harm affects not only vision and hearing, but also the other senses as well. Unpleasant flavours or smells are often regarded by the human brain as important signals about the toxins or microorganisms present in food. But human behavioural defences reach a lot further than that. Any episode of severe sickness may even trigger a life-long aversion to food supposedly responsible for it. The indigestion of a particular substance may be completely harmless, but the brain labels it as dangerous and repulsive due to the sole coincidence in time with the episode of sickness (Garcia, Hankins, Rusniak 1976). In a similar manner, pregnant women are generally more sensitive to even trace amounts of bitterness, which is an adaptation designed for the elimination of a wide variety of plant toxins from the woman’s diet. Usually innocuous for adult organisms, small doses of plant toxins can be potentially lethal for the developing foetus, which is why frequent nausea during pregnancy often corresponds with the lower risk of a miscarriage (Breslin 2013). Food aversions and sensitivity to bitter taste are just two elements of a wide spectrum of behaviours known as the behavioural immune system (BIS). Both the innate and the adaptive immune system are merely reactive due to being able to trigger immune response only after the viral, bacterial or fungal invasion. They are costly in terms of the basal metabolic rate increase and their activity often proves to be debilitating because of associated symptoms connected with high immune activity, such as fever, nausea or constant fatigue. However, protective behaviours comprising the behavioural immune system are purely preventive due to being able to limit the very contact with the toxic substances or lethal pathogens (Schaller 2011). Conclusion Evolutionary psychology offers an interesting insight into the source of human sensory biases. The principle of asymmetric harm allows researchers to interpret systematic distortion of reality as a hard-wired safety mechanism restricting human action whenever environmental clues suggest such a response. Because of that, the partial unreliability of perception seems to be overly adaptive due to it limiting the exposure to toxins, pathogens, and danger- Perceptual Knowledge. An Evolutionary Approach | Marcin Rządeczka ous foes alike. Nevertheless, the catalogue of perceptual biases should not be used to undermine the very concept of objective reality. Most perceptual biases do not occur at random, but are highly predicable due to their systematic nature. Literature Breslin, P.A. (2013) “An Evolutionary Perspective on Food and Human Taste”, Current Biology 23 (9), 409-418. Fessler, D.M.; Holbrook, C.; Snyder, J.K. (2012) “Weapons Make the Man (Larger) Formidability Is Represented as Size and Strength in Humans”, PLOS ONE 7, e32751. Fessler, D.M. (2013) “Bound to Lose: Physical Incapacitation Increases the Conceptualized Size of an Antagonist in Men”, PLOS ONE 8, e71306. Fessler, D.M.; Holbrook, C. (2013) “Friends Shrink Foes. The Presence of Comrades Decreases the Envisioned Physical Formidability of an Opponent”, Psychological Science 24, 797-802. Fessler, D.M.; Holbrook, C.; Pollack, J.S.; Hahn-Holbrook, J. 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