Although the term “unconscious” was only introduced fairly recently (in the 18th century by the German philosopher Platner, the German term being “Unbewusstsein”), the relative “unconsciousness” of human nature has evoked both marvel and frustration for more than two millennia. Socrates (490–399 BC) argued that free will is limited, or at least so it seems, after he noticed that people often do things they really do not want to do. He called this akrasia, which can best be translated as “the lack of control over oneself.” A few centuries later, the Roman thinker Plotinus (AD 205–270) was presumably the first to allude to the possibility of unconscious psychological processes in writing: “The absence of a conscious perception is no proof of the absence of mental activity.”
As far back as the Ancient Greeks people have been interested in the puzzle of the seeming lack of control that we exhibit in our decision-making. What would Socrates have thought if he could see how modern people navigate a typical supermarket? [Image: Mtaylor848, https://goo.gl/GhuC6L, CC BY-SA 3.0, https://goo.gl/eLCn2O]
These two ideas, first verbalized by Socrates and Plotinus respectively, were— and still are—hotly debated in psychology, philosophy, and neuroscience. That is, scientists still investigate the extent to which human behavior is (and/or seems) voluntary or involuntary, and scientists still investigate the relative importance of unconscious versus conscious psychological processes, or mental activity in general. And, perhaps not surprisingly, both issues are still controversial.
During the scientific revolution in Europe, our unconscious was taken away from us, so to speak, by the French philosopher Descartes (1596–1650). Descartes’s dualism entailed a strict distinction between body and mind. According to Descartes, the mind produces psychological processes and everything going on in our minds is by definition conscious. Some psychologists have called this idea, in which mental processes taking place outside conscious awareness were rendered impossible, the Cartesian catastrophe. It took well over two centuries for science to fully recover from the impoverishment dictated by Descartes.
This is not say that contemporaries of Descartes and later thinkers all agreed with Descartes’s dualism. In fact, many of them disagreed and kept on theorizing about unconscious psychological processes. For instance, the British philosopher John Norris (1657–1711) said: “We may have ideas of which we are not conscious. . . . There are infinitely more ideas impressed on our minds than we can possibly attend to or perceive.” Immanuel Kant (1724– 1804) agreed: “The field of our sense-perceptions and sensations, of which we are not conscious . . .is immeasurable.” Norris and Kant used a logical argument that many proponents of the importance of unconscious psychological processes still like to point at today: There is so much going on in our brains, and the capacity of consciousness is so small, that there must be much more than just consciousness.
The most famous advocate of the importance of unconscious processes arrived at the scene in the late 19th century: the Austrian neurologist Sigmund Freud. Most people associate Freud with psychoanalysis, with his theory on id, ego, and superego, and with his ideas on repression, hidden desires, and dreams. Such associations are fully justified, but Freud also published lesser-known general theoretical work (e.g., Freud, 1915/1963). This theoretical work sounds, in contrast to his psychoanalytic work, very fresh and contemporary. For instance, Freud already argued that human behavior never starts with a conscious process (compare this to the Libet experiment discussed below).
Freud, and also Wilhelm Wundt, pointed at another logical argument for the necessity of unconscious psychological processes. Wundt put it like this: “Our mind is so fortunately equipped, that it brings us the most important bases for our thoughts without our having the least knowledge of this work of elaboration. Only the results of it become conscious. This unconscious mind is for us like an unknown being who creates and produces for us, and finally throws the ripe fruits in our lap.” In other words, we may become consciously aware of many different things—the taste of a glass of Burgundy, the beauty of the Taj Mahal, or the sharp pain in our toe after a collision with a bed—but these experiences do not hover in the air before they reach us. They are prepared, somehow and somewhere. Unless you believe consciousness is causally disconnected from other bodily and mental processes (for instance if one assumes it is guided by the gods), conscious experiences must be prepared by other processes in the brain of which we are not conscious.
The German psychologist Watt (1905), in an appealing experiment, showed that we are only consciously aware of the results of mental processes. His participants were repeatedly presented with nouns (e.g., “oak”) and had to respond with an associated word as quickly as they could. On some occasions participants were requested to name a superordinate word (“oak”-“tree”), while on other occasions they were asked to come up with a part (“oak”-“acorn”) or a subordinate (“oak”-“beam”) word. Hence, participants’ thinking was divided into four stages: the instructions (e.g., superordinate), the presentation of the noun (e.g., “oak”), the search for an appropriate association, and the verbalization of the reply (e.g., “tree”). Participants were asked to carefully introspect on all four stages to shed light on the role of consciousness during each stage. The third stage (searching for an association) is the stage during which the actual thinking takes place and hence this was considered the most interesting stage. However, unlike the other stages, this stage was, as psychologists call it, introspectively blank: Participants could not report anything. The thinking itself was unconscious, and participants were only conscious of the answer that surfaced.