Book Review: The User Illusion

In The User Illusion: Cutting Consciousness Down To Size (Penguin Books, 1991, English translation 1998), Danish science writer Tor Norretranders dissects the powerful illusion that humans believe that what they see and think is accurate or real. The User Illusion (TUI) relentlessly describes human consciousness and the biological basis for the false realities that we believe are real. TUI is about the constraints on knowledge. The 2nd law of thermodynamics and the curse of always increasing disorder (entropy), information theory and mathematics all make it clear that all sentient beings in the universe operate under severe information constraints. That includes the limits on the human mind. To believe otherwise is a mistake, or more accurately, an illusion.

TUI’s chapter 6, The Bandwidth of Consciousness, gets right to the heart of matters. Going there is an enlightening but humbling experience. When awake, the information flow from human sensory nerves to the brain is about 11.2 million bits per second, with the eyes bringing in about 10 million bits per second, the skin about 1 million bits per second, with the ears and nose each bringing in about 100,000 thousand bits per second. That’s a lot, right? No, it isn’t. The real world operates at unknowable trillions of gigabits/second, so what we see or perceive isn’t much. It’s puny, actually. Fortunately, humans needed only enough capacity to survive, not to know the future 10 or 100 years in advance or to see a color we can’t see through human eyes with just three different color sensing cell types (red, green, blue). For human survival, three colors was good enough. Evidence of evolutionary success is a planet population of about 7.4 billion humans that’s rapidly heading toward 8 billion. 

Given that context, that 11.2 million bits/second may sound feeble but things are much weirder than just that. The 11.2 million bits/second are flowing into our unconscious minds. We are not conscious of all of that. So, what is the bandwidth of consciousness? How much of the 11.2 million bits/second we sense do we become aware of? The answer is about 1-50 bits/second. That’s the estimated rate at which human consciousness processes the information it is aware of. Silently reading this discussion consumes about 45 bits/second, reading aloud consumes about 30 bits/second, multiplying and adding two numbers consumes about 12 bits/second, counting objects consumes about 3 bits/second and distinguishing between different degrees of taste sweetness consumes about 1 bit/second.

What’s going on here??: It’s fair to ask what's really going on and why does our brain operate this way. The answer to the last question is that (i) it’s all that was needed to survive, and (ii) the laws of nature and the nature of humans, which are severely limited in data processing capacity. The human brain is large relative to body size but nonetheless only it processes information at a maximum rate of about 11.2 million bits/second, most of which we never become consciously aware of. That's human bandwidth because that’s what evolution resulted in. What’s going on is our unconscious mind taking in information at about 11.2 million bits/second, discarding or withholding from consciousness what’s not important or needed, which is about 50 bits/second or less, and then presenting the little trickle of important information to consciousness. That’s how much conscious bandwidth (consciousness) that humans needed to survive, e.g., to finagle sex, spot and run away from a hungry saber tooth cat before being eaten, find or hunt food, or do whatever was needed to survive. In modern times, our mental bandwidth is sufficient to do modern jobs, build civilization and advance human knowledge. Where things get very strange is in the presentation of the little trickle to consciousness. Discussing that step is a different discussion, but a glimpse of it as applied to politics is in the Democracy for Realists book review. This discussion focuses on the human brain operating system and the inputs and outputs it deals with and creates.

If one accepts the veracity of the science and Norretrander’s narrative, it is fair to say that the world that humans think they see is more illusion than real. Other chapters of TUI and the science behind the observations reinforce this reality of human cognition and its limits. For example, chapter 9, The Half-Second Delay, describes how our unconscious minds make decisions about 0.5 second before we become aware of what it is we have unconsciously decided. Although there's room for some disagreement about it, we consciously believe that we made a decision about 0.5 second before we became aware of it. Current data suggests that decisions can be made unconsciously about 7 to 10 seconds before we're aware of the decision. We trick ourselves. In other words, we operate under an illusion that our conscious mind makes decisions when that's the exception. The rule is that our unconscious minds are calling the shots most of the time. When it comes to perceiving reality, the low-bandwidth signal the brain uses to create a picture is a simulation that we routinely mistake for reality. As Norretranders sees it, consciousness is a fraud. That’s the user illusion.