Our imperfect brains sometimes link events that have little or no causal connection. Superstitions work that way. Every time I wash the car, it rains. You might think that artificial brains don’t have that little flaw – but they do. Computer folks call it overfitting. That means that these non-human “brains” also sometimes use an irrelevant detail in constructing a model.
Those neural network machines and creatures are definitely very good at learning relevant details and making connections but they also learn irrelevances.
How do humans deal with overfitting? How do we generalize from our many daily experiences to other similar situations? We dream.
That conclusion comes from research by Erik Hoel who says dreaming evolved specifically to deal with this problem. If he is correct, then it might solve a longtime problem in neuroscience of trying to figure out why we dream at all.
Sigmund Freud thought we dream to deal with taboos, but that isn’t accepted as correct these days. Another theory is that dreams are the way the brain sifts through memories of the recent past selectively discarding unwanted or unneeded ones. But the dreams we recall aren’t very realistic and they don’t really seem to deal with the day’s memories.
Computer science is not my field but from what I’ve read one of the ways of dealing with overfitting in computer networks includes adding “noise” to the learning process so that it’s difficult for the network to focus on irrelevant detail. They call this dropout. It seems counterintuitive. Noise to improve focus?
But perhaps that’s what dreams do – insert “noise.” An example that is given is that we can trigger dreams by playing simple repetitive games such as Tetris for an extended time so that the brain becomes overfitted.
The theory also suggests that there can be dream substitutes. Books, plays, films, and the arts, in general, might perform a similar role to dreams since they are also an injection of false information.
I’ve read in numerous places that you can deprive people of sleep (in experiments and in torture) and they can survive longer than if you deprive them of dreaming. Experiments found that waking people up whenever they began REM sleep but allowing them to go back to sleep didn’t make them tired but it did make them a bit crazy. Studies have connected poor quality of sleep to a higher risk of heart disease, obesity, and even Alzheimer’s Disease, so there is that connection to dreaming. If you don’t sleep, you won’t dream. And though people often say “I never dream,” they do dream – but they don’t remember them when they wake up.
Ironically, most antidepressant medications significantly suppress REM/dreaming. (SSRIs suppress REM sleep by about a third, tricyclics reduce it by half, and older monoamine oxidase inhibitors cut out nearly all REM sleep.) Also, sleep deprivation can lead to more intense dreaming.
Returning to Philip K. Dick’s book, I was curious about the inspiration for his story. It actually began when he was doing research for another book, The Man in the High Castle. (That novel has also been adapted for a continuing TV series on Amazon Prime.) He was reading seized WWII Nazi diaries. It led him to believe that those beings were monsters who pretended to be human.
In one of the journals, a Nazi officer complains about not being able to sleep because he was “kept awake at night by the cries of starving children.” Instead of empathizing with their suffering, the officer only saw them as a nuisance that disturbed his sleep. That one line had a deep impact on Dick who thought, “It is not human to complain in your diary that starving children are keeping you awake.”
And so it started him thinking about a new book with “androids” who lacked any empathy. Empathy is the main theme of his novel Do Androids Dream of Electric Sheep? The protagonist in that book, Deckard, is human but realizes that some of the machine androids seem capable of empathy while some humans appear to be devoid of it.
It seems that he may be correct. Androids do dream. Whether they dream of electric sheep is questionable. I have never dreamed of any kind of sheep at all.