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Chapter I: Uniqueness of the Human Mind >> Non-linguistic tests of mental synthesis

Non-linguistic tests of mental synthesis

Animals can learn by trial and error

Above, we looked at two experiments designed to test problem-solving abilities in naïve animals. A naïve dog holding a stick in its teeth was not able to use mental synthesis to understand that it needs to rotate its head in order to pass through a fence in which one vertical piece was removed. A chimpanzee was not smart enough to remove nuts from inside a watermelon through a small opening. These tests indicate that at least some animals may not be capable of mentally planning and testing the outcome of their actions as humans can do using the process of mental synthesis.

However, these types of experiments are really difficult to conduct. The problem is that an animal can learn to perform a task by trial and error or learn from observing others. Thus, when the animal encounters a similar problem at a future time, it may solve the problem by just remembering the solution. In other words, the animal can solve the problem without visual mental planning, that is, without mental synthesis. The dog can remember to rotate the stick vertically. The chimp can learn to flip the watermelon to get the nuts. Once an animal has learned the trick, it no longer needs to use mental synthesis to find the solution; the solution is available to the animal as a conditioned reflex. For tests that examine mental synthesis, the subject of the test must be naïve, that is, without any prior exposure to the solution. The naïveness of a subject is nearly impossible to insure. Therefore, the above tests are not ideal for testing mental synthesis in animals.

Another possible test of mental synthesis involves a subject classifying from memory the letters of the alphabet according to the relative heights of their lower case forms (letter classification task, Weber, 1979). For example, the letter ‘a’ and the letter ‘h’ are shown or named to the subject and the subject is asked to identify the taller letter. The letters are introduced one at a time with a short pause in between. It is generally believed that people perform the letter-height comparison by generating a visual image of the lower case letter and examining the image to assess letter height. In other words, we remember the discrete images of ‘a’ and ‘h’, but we do not store in memory the image of ‘a’ next to ‘h’ - the image of ‘a h’. Therefore, in order to compare the heights, we generate a new image of ‘a h’ in the process of mental synthesis. After the new image is formed, we mentally examine the ‘a h’ image, and decide that ‘h’ is taller. This experiment is also not ideal because after a long period of training, a subject can memorize all the letter pairs. That is, a subject will remember that ‘h’ is taller than ‘a’; that ‘d’ is taller than ‘c’, and so on. Therefore, the subject would no longer need to synthesize the image of ‘a’ with the image of ‘h’ in the process of mental synthesis (constructing a new image), but can generate the answer without ever visually comparing ‘a’ and ‘h’ in the mind. For the same reason, the letter classification task and similar experiments may not be applicable for testing mental synthesis in animals.

Animals may use reflexes to solve problems

From time to time there are reports of smart animals solving complex problems that “require thinking”.  Wolfgang Köhler showed that chimpanzees spontaneously stacked boxes to stand on in order to reach the fruit hanging from a high ceiling. Chimpanzees also used long sticks to reach food outside their enclosure. An excellent Nova movie “Ape Genius” (2008) documents an amazing range of problems that can be solved by chimpanzees (Website 1.1).

This chimpanzee is using a stick to get food from a tree.

Even birds show a fascinating problem-solving capacity, despite their lack of a neocortex (the neocortex is the convoluted outer layer of the brain linked to higher cognitive functions in mammals). For example, when hiding their food, ravens (a select group of crows), make a mental note of the food’s “expiration date”. They also check for onlookers before storing their provisions. If any are present, they stage a sophisticated show to conceal what they are doing.

Bernd Heinrich and Thomas Bugnyar showed that ravens confronted with food hanging on a string were able to devise a way to get it. To get the food, the raven had to reach down from a perch, grasp a string in its bill, pull up on the string, place the loop of pulled-up string onto the perch, step on the string, then let go of the string, and reach down again, repeating this sequence six or more times in a row. The scientists reported that some adult birds were able to solve the problem and get the food. In fact, the birds’ approach to the solution was very human-like. The raven would examine the set-up for several minutes (almost as if it was planning its actions) and then perform the procedure on its first try in as little as 30 seconds. Note that the raven was never given an opportunity for trial and error learning - nether in the lab, not in the wild. The scientists concluded that “the simplest suggestion is that they [the ravens] imagined possibilities and figured out what steps to take.”

Photographs of a bird brain (left) and a human brain (right). Notice the absence of convolutions in the bird brain. Not to scale: the bird brain is actually much smaller than the human brain.

There is no doubt that humans would use mental synthesis to solve the problem presented to the ravens. A human would visually generate multiple plans in the mind and then select the plan that solves the problem. However, it could be argued that the ravens did not use mental synthesis but rather acted upon their hard-wired (innate) reflexes. In the wild, ravens prey on small invertebrates, amphibians, reptiles, small mammals and birds. Separating the meat from the bones of dead animals is not an easy task. A raven must have a significant genetic background for pulling pieces of meat hanging on ligaments from dead bodies. Thus, in the experiment above, the ravens could have mixed and matched their arsenal of reflexes to solve the problem.

Consider birds feeding on aquatic animals. Refraction of light at the water-air boundary makes objects in the water appear to be at a position that is different from their physical location. (To test this, lower a pencil into a bowl of water and try to reach the tip of the pencil located underwater.)

Pencil in water. The dark rectangle represents the physical position of a pencil in water. The light rectangle represents the apparent position of the pencil. If you try to reach pencil’s end in water, you will reflexly aim for point Y, not for the physical location X.

A human trying to grab a fish that is swimming underwater is destined to miss (unless the human is looking straight down at the water surface in order to avoid refraction). Birds, on the other hand, can reflexly generate an impeccable dive to catch a fish. Aquatic herons, for instance, are able to fully accommodate for the refraction of light (Katzir, 1987; Lotem, 1991) and precisely calculate the location of a fish in water - a visual reflex that humans lack. Clearly, humans can use mathematics to correct for the refraction of light and calculate the difference between the apparent location of the fish and its actual physical location. Humans can then use mental synthesis to imagine where the fish is physically located. Thus, while birds are using their visual reflexes to solve a problem, humans must use mental synthesis. This is an example of behavior for which birds have an advanced reflex that is absent in humans.

Chimpanzees in the wild often need to reach objects hanging high in the trees. Consequently, they must have developed a range of reflexes that could help them solve the problem. Further, chimpanzees often need to work cooperatively to benefit themselves and their group. Watching chimpanzees help each other obtain a reward (as in “Ape Genius” Nova 2008) leaves the viewer with an impression of a well-planned action. The same can be said about the collective construction projects undertaken by ants and bees. Although ants and bees are considered to be very intelligent, we would be hard pressed to find someone willing to argue that these insects are involved in visual planning of their nests. On the other hand, humans would not be able to build an ant nest or a beehive without visual planning based on mental synthesis. Does it mean that ants and bees are capable of mental synthesis? No. It just means that in the course of evolution, ants and bees acquired some very complex reflexes.

Animals are impressively complex organisms perfected for survival. While humans can sometimes only solve a given problem mentally by visualizing the solution using mental synthesis, animals can often just put together a series of complex reflexes to solve a problem. Humans may have never developed those reflexes or we may have completely lost them in the process of evolution.

It is difficult to find a definitive non-linguistic test for mental synthesis in animals. Even complex problem-solving tasks can often be performed without mental synthesis. A lot of solutions are hard-wired into animals and humans via reflexes. In addition, some solutions are learned and do not require mental synthesis at the time of execution (typing, stopping a car on the red light). The combination of such hardwired and learned reflexes may yield a solution to a problem in the absence of mental synthesis. Since humans can solve problems using mental synthesis, it is often easier for us to conclude that an animal solving the same problem also used mental synthesis. My prediction is that all animals lack the capacity for mental synthesis and therefore will perform poorly in experiments that truly test mental synthesis. No animal can ever beat a human at chess.

How can animals make tools without mental synthesis?

Primates are widely recognized to use tools. As we discussed above, chimps trim branches to make sticks for termite-fishing and make spears for hunting bushbabies. How do chimps know to sharpen a spear for bushbaby hunting? If you think that a chimp pictures the sharp spear in its mind and then mentally plans how it will convert a stick into a sharp spear, you are mistaken. As discussed above, experimental evidence suggests that chimps lack the capacity for mental synthesis. When chimps look at the stick, they do not have a mental template for the sharp spear. Nor can chimps mentally plan the process of stick sharpening. Chimps cannot imagine themselves biting on a stick to make it sharp.  When chimps look at the stick, they perceive the stick and nothing else. Then how do chimps know to bite on a spear to make it sharp? The answer is that chimps simply remember that they need to bite on a stick to make it sharp. The same is true for termite fishing. Chimps remember that they need a long stick to fish for termites. At some point in time, some chimp stumbled upon the solution. Other chimps learned the technique by observing that first chimp. Making a spear and cleaning a long stick for termite fishing are nothing more than conditioned reflexes. Chimps learn to associate the tasty meat of a bushbaby with biting on a spear and the delicious taste of termites with cleaning a long stick. One indication that chimps are using a series of automated actions (conditioned reflexes) rather than mental synthesis to make their tools, is the length of time necessary to learn the technique. Unlike humans who can learn the skill after watching termite fishing only once, it normally takes several years for chimps to become fully skilled at the technique. Chimps first learn that they need a termite mound; then they learn that they need a stick, and they just roll the stick over the mount for weeks. Only later do they learn to put the stick into the hole. At first they often have difficulty figuring out the correct size of the tool, trying to use a stick that is too thick. Clearly, the chimps’ learning method looks more like a trial-and-error process: when they finally find a solution, they just remember the actions that brought them the reward (termites). This long time frame of technique acquisition is similar to that needed by humans to learn to play tennis, ski, ice skate, play a musical instrument, drive a car, or type on the computer -  this is the time frame characteristic for learning a series of automated actions. Do you remember yourself learning how to ice skate? In the beginning you couldn’t control your body well, the skates just refused to obey your commands. It may have taken months if not years before you developed a series of automated actions that made your ice-skating more of a pleasure than an excruciating task of learning and falling. Another indication that chimps are using a series of automated actions is that each technique is highly conserved within a given population of chimpanzees. Innovation is either lacking or extremely slow.

The concept of using a series of automated actions to achieve a productive result is extremely difficult to understand for a modern human because modern humans nearly always plan their actions visually in the mind. We (modern humans) solve most problems by imagining the solution in the process of mental synthesis. The way a modern human would manufacture a sharp spear is by planning the task in the mind first (using mental synthesis), and then implementing the procedure on a stick. Is it possible to manufacture a sharp spear without relying on mental synthesis for visual planning of the fabrication process? Are there examples of productive human actions that do not involve mental synthesis?

To put ourselves into the chimp’s “shoes” we need to completely stop our imagination. Here are a few examples in which modern humans solve complex problems and perform intricate tasks without using mental synthesis and by relying only on a series of automated actions:

Performing repetitive manual work. Repetitive manual work such as knitting, typing, or using brakes to stop a car on a red light often does not require mental synthesis [1]. An experienced knitter can make a scarf without thinking about the work; the hands simply remember where to go. The information is still processed by the visual system, but the mind is not involved in imagining the next move (no mental synthesis). Again, just as is the case of a chimpanzee making a spear, the result (the scarf) is achieved without mental synthesis.

Driving on a familiar road. How often have you started driving to work, when you meant to go somewhere completely different, such as to a museum? You drove using your memory and conditioned reflexes without thinking about the driving. To an outside observer your driving would look like a complex task that must have required the use of mental synthesis. But you know that you drove to work rather than to the museum, therefore you were not visually planning the route. Your visual system perceived and processed the information about the road so that you could make the turns and stop on the red light, just like a chimpanzee’s visual system perceives and processes the information about the stick. However, you were not actively visualizing driving to the museum. Your mind did not synthesize the plan that would have taken you where you wanted to go. You achieved some results (you drove to work) without actively thinking, that is, without mental synthesis. Thus, it should come as no surprise that a chimpanzee can make a spear without first having an execution plan in its mind.

Half asleep. In the morning, when you are still half-asleep, have you ever done something like accidentally pour milk on top of your pancakes? To an outside observer your actions look well planned. You open the refrigerator, pull out a carton of milk, and pour milk on top of the pancakes without spilling a drop. A naive observer would be convinced that you have used mental synthesis to plan your actions. However, that morning you were half-asleep and you were clearly not planning your actions in your mind. If you were planning the action, you would have poured syrup on top of the pancakes instead of milk.

Intoxicated. The last time you came home after a few drinks, you were able to open the door with your keys and drop dead on the bed. But you probably did not mentally plan to open the door. You acted from your memory to automatically pull out the keys, insert them into the keyhole, open the door, and go to bed. To an observer, the procedure of opening the door would look like a task that required thinking, but you never planned these actions (no mental synthesis was involved). You just remembered the sequence of moves.

Modern humans, when tired, anxious, ill, distracted, hurried, or intoxicated, that is, when the capacity for mental synthesis is diminished, often rely on reflexes and learned automatic behavior (conditioned reflexes). Then why is it so hard for us to believe that a chimpanzee only relies on its conditioned reflexes to make a sharp spear?

Humans do not always use mental synthesis even when it is vitally important

Humans do not always use mental synthesis, even when it is vitally important. A good collection of examples of people not using mental synthesis is presented at DarwinAwards.com. Here are a few paraphrased stories:

The following robbery attempt occurred in Washington, DC. A would-be criminal walked in to a gun shop: H&J Leather & Firearms. The shop was full of customers shopping for firearms. To enter the shop, the robber had to step around a marked police patrol car parked at the front door. A uniformed officer was standing at the counter, having coffee before work. Upon seeing the officer, the robber announced a holdup, and fired a few wild shots. The officer and a clerk promptly returned fire, covered by several customers who also drew their guns, thereby removing the confused criminal from the gene pool of humanity. Had the robber used mental synthesis to imagine the actions of the uniformed police officer, the store clerk, and the armed customers, he could have saved his life.

Six people drowned while trying to rescue a chicken that had fallen into a well in the village of Nazlat Imara, 240 miles south of Cairo, Egypt. An 18 year old farmer was the first to descend into the 60-foot well. He drowned, apparently after an undercurrent in the water pulled him down. Police said that his sister and two brothers, none of whom could swim well, went in one by one to help him, but also drowned. Two elderly farmers then came to help. But they apparently were pulled by the same undercurrent. The bodies of the six humans were later pulled out of the well. The chicken was also pulled out. It survived. Mental synthesis could have saved lives if rescuers could have planned the descent with the use of a rope or a ladder.

Eric A. Barcia, a 22-year-old resident of Reston, Virginia, was found dead after he used bungee cords to jump off a 70-foot railroad trestle. The fast food worker taped a number of bungee cords together and strapped one end around his foot. Barcia had the foresight to anchor the other end to the trestle at Lake Accotink Park, and he even remembered to measure the length of the bungee cords to make sure that they were a few feet short of the 70 foot drop. He proceeded to fall headfirst from the trestle, and hit the pavement 70 feet below several seconds later. The Fairfax County police report said "The stretched length of the cord that he had assembled was greater than the distance between the trestle and the ground."

Clearly, mental synthesis is not always employed by modern humans.