You wake up in a new world. Your eyes open to bright, confusing lights. Your ears are filled with mysterious sounds. Everything around you feels unfamiliar. This is a reality of a newborn baby. So what is it like to be a newborn? For a philosopher and a psychologist like me, this is a fascinating question. It is hard enough to know what's going on in adults' minds. What could be going on in a newborn baby's mind? Do babies have consciousness? The subjective experience of their mind and the world. In adults, consciousness involves experiences of seeing, hearing and thinking, and feelings of pain, pleasure and emotions. Do babies also have this experience and feelings that light up their inner world?
So the traditional view is that newborns are passive observers of overwhelming chaos, and they may not be conscious at all. It sounds unbelievable today, but 50 years ago, doctors routinely performed circumcision without anaesthetic, convinced that newborns' immature brain could not feel pain. Since then, developmental psychologists have shown that infants' abilities are much more complex than we thought before. But the question of infant consciousness has remained open. One problem is that infants cannot tell us how they feel. They cannot describe their thoughts. And they certainly cannot take a consciousness test. So how can we know what's going on inside their minds?
One answer is to measure infants' brains. Over the past few decades, the science of consciousness has told us a lot about the brain basis of consciousness in adults. We found neural signals that are only active when an adult is consciously perceiving a stimulus. Recently, neuroscientists found the same neural signals in infants' brains. These provide powerful new evidence that infants might be actively experiencing their surroundings from a remarkably early age.
One innovative experiment in neuroscience is the audible paradigm. This is a test of how our brain reacts when something unexpected happens. I love this paradigm, and here’s how it works. Imagine repeatedly hearing the same sequence of sounds. Beep, beep, beep, boop. Beep, beep, beep, boop. Beep, beep, beep, boop. Suddenly, this familiar pattern is interrupted by a different sequence. Beep, beep, beep, beep. Instantly, your brain detects the surprise, producing a measurable brain signal called the P300 wave. This oddball response to an expected sequence of sounds only happens when an individual is conscious. People in deep sleep don't have it. People in comas don't have it. But newborn babies do. The neuroscientist Ghislaine Dehaene has found that when babies are just a few days old, they show the same type of brain activity in response to this oddball sequence of sounds. What this suggests is that right from birth, infants might be truly experiencing conscious perceptions and conscious expectations.
Researchers have also looked for consciousness through patterns of attention in the brain. In conscious adults’ brains, different types of networks alternate their activity when we switch our attention between the external world and our internal thoughts. You know how it is. You might be doing this right now. You focus your attention on the speaker for a while, and then you daydream for a while. (Laughter) It turns out that infants do the same sort of thing. The neuroscientist Lorina Naci recently observed the same type of alternation between these networks in newborn brains. This suggests that these switches of focus of internal and external awareness are present right from birth. There is also evidence from gaps in attention. When our mind intensely focuses on one thing, it usually becomes blind to something that happens immediately afterward. We call this phenomenon attentional blink. Infants experience this phenomenon too, but in slow motion. At three months old, infants take near a full second to shift their attention from one visual cue to another, compared to adults that can manage this shift much faster. Amazingly, infants showing the same type of brain response when this happens is strongly hinting they are actively experiencing their environment.
Researchers have also found relevant brain patterns in premature infants. Which makes you wonder, could consciousness begin before birth? This is a really important question. I told you all how scientists apply the audible test to newborns. Well, they applied the same test to late-term fetuses around 35 weeks into pregnancy. The results were striking. Fetus shows the same type of brain response as we found in newborns. So even before birth and entering the world, babies seem to be capable of consciously processing sounds, meaning their awareness might develop while they are still in the womb. Of course, these results have potential implications scientifically, medically and ethically. For a start, we now know that when we perform surgery on newborns or premature infants or late-term fetuses, we should give them an anesthetic. I know that many of you will be thinking about the abortion debate. In that context, I should stress that our strongest evidence is that consciousness requires brain structures that emerge after 24 weeks of gestation, a time when abortion is rare. The new evidence [that newborns are conscious] might extend to fetuses in third trimester of gestation, but it doesn't extend to earlier than that. This is a new understanding, and this new understanding is a work in progress, but might change our picture of newborn babies. They are not passive creatures waiting for consciousness to switch on. They are tiny humans already perceiving patterns and interacting with the world in a meaningful way. As human life unfolds, consciousness unfolds with it. Our sense of ourselves grows and changes. Our consciousness waxes and wanes until one day it ends. From the moment we take our first breath to the moment of our deaths, our lives are lit by the flame of awareness. We share this flame with other animals and we might one day share it with machines. Collectively, our conscious minds illuminate the universe, and though each flame eventually fades, the light of consciousness never disappears. It is rekindled with each new life in the endless dance of existence. Thank you. (Applause)