In the previous post, I commented on some ways that children of different ages are of "different species" (so to speak) from adults. The developmentalist Jean Piaget described young children as "cognitive aliens" who are so different in their thought patterns that adults have to struggle to understand the experiences of the very young. Piaget described differences like "transductive logic", a pattern in which a child assumes that if two events have one thing in common, they must have other things in common to-- even to the point where one might be able to cause the other. For example, Piaget described how his young daughter wanted an orange, but the unripe fruit was in a sunny window waiting to change from green to its bright, ripe color. (This was in Switzerland in the 1920s so ripe citrus fruit was not to be found everywhere.) The little girl was told she had to wait for the fruit to turn orange, but when she was given a cup of orange chamomile tea, she declared "It's orange now-- I can have the fruit!" In her transductive view, the fruit should be orange if the tea was orange; the orange tea was ready to drink, so the fruit should be ready too.
Modern preschoolers also give us good examples of transductive logic. How about fire trucks, for example? You see fire trucks at places where there are fires; in addition, we tell the child not to be afraid because the fire truck "puts out fires". But we also say "put out the cat","put out the garbage" , and between our comments and transductive logic, the child comes to the conclusion that fire engines cause fires! Not very different is the common early childhood belief that trees cause the wind to blow by waving their branches.
One set of challenging problems for young children is the category called "class inclusion problems". These problems involve objects that have two or more salient characteristics, so they can be grouped or classed in more than one way. For example, a set of blocks can be both different colors and different shapes. Preschoolers can be good at separating the red ones from the blue ones, or squares from rectangles, but still have trouble figuring out what to do with blocks that all have one thing in common (like being made of wood), but are different in color or shape. For example, suppose you have a set of 10 wooden blocks , 7 of them are painted red, and 3 are not painted at all. A preschooler can identify the blocks as all made of wood, can identify the ones that are painted, and can count the blocks. But ask the child: "Are there more wooden blocks, or are there more painted blocks?", and the reply will probably be that there are more painted blocks!
The difficult part of this block problem is that the child forgets about the broadest class (wooden blocks) and reinterprets the question to refer to two narrower classes, painted wooden blocks and unpainted wooden blocks. Both of those narrow classes are actually included in the broader class of wooden blocks. But the problem asks the child to skip back and forth from the broad class to a narrow class which is included in the broad class, which is a much more difficult task than counting or identifying colors.
The inability to solve class inclusion problems is a source of cute but puzzling childhood mistakes: "Are you Catholic?" "No, I'm a girl." Even young children whose mothers are physicians may insist that the mother must be a nurse, because "girls can't be doctors", and no doubt the same kind of problem occurs for fathers who are R.N.s. In each case, a narrower class--- gender-- has to be included within a broader class, whether religion or profession. To the adult, it's self-evident that being a girl does not rule out being Catholic or anything else, but that's because the adult can easily solve class inclusion problems and generally no longer even realizes that these are problems to be solved.
One other cognitive difference between young children and adults has to do with conservation--- not a concern with forestry, but the understanding that many characteristics of material objects are unchanging (conserved) unless something happens to change them. Preschoolers usually have trouble conserving volume and number. They think that a ball of Playdoh changes in amount as well as shape when it's flattened out, and that a row of buttons pushed close to each other is fewer in number than the same row of buttons moved farther apart, even though when the child counts the buttons the count is the same. This means that the child's understanding of numbers fluctuates with the objects being counted. It also means that preschoolers will complain loudly at a birthday party if one's slice of cake is standing up and another's is lying down-- the "tall" piece of cake is understood as bigger than the "short piece.