by Anne Pycha
It’s the first Thanksgiving with baby Mattias, our second child. He kicked off the holiday by waking up four times last night. When he was tiny, he would wake and cry for five minutes at a time, then go back to sleep. Now that he is nine months old, he cries for five minutes, then becomes conscious that he’s crying, which makes him cry even more.
Consciousness has been on my mind since last month, when Mattias participated in an experiment at our local university. A friendly graduate student placed electrodes on his scalp, which measured the event-related potentials (ERPs) that his brain produced while he watched images and listened to sounds. Mattias didn’t have to do anything except look at the computer screen in front of him. That is, he did not have to provide any conscious response to the images or sounds. But he did give an unconscious response, because his brain reacted to the stimuli in ways that he himself wasn’t aware of, as measured by the ERPs.
Collecting ERPs requires special equipment, but babies also respond to their environment in low-tech ways that anyone can observe. They suck on a bottle faster, or slower. Their hearts produce more beats per minute, or fewer. They gaze for a longer period of time at a picture, or for a shorter period. They keep their head in a particular orientation, or turn it toward something new.
Researchers have collected all of these types of data, often to demonstrate that babies exhibit a particular skill or behavior that adults lack. For example, as Barbara Conboy and her colleagues summarize, babies respond to differences between unfamiliar speech sounds that adults cannot detect. It’s just that the responses they give to the speech sounds are not conscious ones.
But how can a baby know something, when he does not know that he knows it? Antonio Damasio provides some thoughtful answers to this question in his book, The Feeling of What Happens. Damasio forms a distinction between unconscious responses, which he calls “emotions”, and conscious responses, which he calls “feelings”. All animals exhibit emotions, which consist of nothing more than transient chemical or neural patterns that the organism produces in response to a change in the environment.
Damasio gives the example of a sea anemone, which can extend its tentacles outward and open up to the world, or contract its tentacles and hide. The anemone exhibits no consciousness of these emotions, but they are emotions nevertheless. As Damasio writes, “The essence of joy and sadness, of approach and avoidance, of vulnerability and safety, are as apparent in this simple dichotomy of brainless behavior as they are in the mercurial emotional changes of a child at play.”
Feelings differ from emotions because they involve distinctly conscious responses. For Damasio, feelings are second-order mental patterns that encode not only emotion but also, crucially, the organism’s relationship to his or her emotion. So when Mattias cries, that’s an emotion. When he cries harder because he realizes he is crying, that’s a feeling, and the beginning of consciousness.
Interestingly, when researchers probe the unconscious responses of adults, rather than the conscious ones, they sometimes find that adults resemble babies more than previously thought. For example, ERP measurements demonstrate that in fact, adults respond to the same differences between unfamiliar speech sounds that babies do, even though the adults cannot consciously report hearing those differences. As lead author Maritza Rivera-Gaxiola and colleagues write, “the brain retains the ability to detect differences that the subject is not aware of”. Put differently, adults exhibit emotions in response to the speech sounds. Potentially, if they pushed their mental respresentations to the next level, they could form feelings about them as well, and develop an actual consciousness of the difference.
Strange as it seems initially, Thanksgiving is actually a good time to reflect on these mental capacities. It can be a day of heightened emotions, because we respond strongly yet often unconsciously to the sounds of familiar people and the smells of familiar foods. It can also be a day of heightened feelings, because we take the time to think consciously about what those people and foods mean in our lives. Baby Mattias, this one’s for you.
Conboy, Barbara T., Maritza Rivera-Gaxiola, Juan Silva-Pereyra, & Patricia K. Kuhl. 2008. Event-related potential studies of early language processing at the phoneme, word, and sentence levels. In Angela D. Friederici & Guillaume Thierry (eds.) Early Language Development: Bridging Brain and Behaviour. Amsterdam: John Benjamins.
Damasio, Antonio R. 1999. The Feeling of What Happens: Body and Emotion in the Making of Consciousness. New York: Harcourt Brace.
Rivera-Gaxiola, M., G. Csibra, M.H. Johnson, & A. Karmiloff-Smith. 2000. Electrophysiological correlates of cross-linguistic speech perception in native English speakers. Behavioural Brain Research 111:13-23.