Pride, guilt and self-consciousness are uniquely human characteristics, the British Association annual science festival heard this week. Uta Frith of University College, London, made the claim after integrating various pieces of research and scholarship.
Our rich and varied mental and social lives make humans fundamentally different from other species, Professor Frith said. Our self-consciousness is different from the self-awareness exhibited by great apes, she said. It occurred only in human evolution, probably about 100,000 years ago.
Self-consciousness manifests itself early in childhood. Infants want to know what other people try to show them, Professor Frith said - if someone points at an object, a small child will look at it.
This ability is not shared by other species, she added, and children from different cultures all develop this ability. Aesop's fable of the fox and the raven is understood by children today, despite being written as part of a much earlier, very different culture.
Professor Frith has studied self-consciousness by questioning autistic people, who have little or no awareness of themselves or others. This research shows that a critical cognitive mechanism is impaired, she said. "Self-consciousness has a basis in the brain. Autism, a brain-based disorder, impairs and delays the emergence of self-consciousness."
For her research, Professor Frith told two stories to a group of autistic people and a control group. In the first, an elderly lady called Mrs Peabody is struggling with heavy shopping when a young man approaches. Fearing that she is about to be mugged, she screams for help, but the man merely wants to give her a hand.
In the second story, Mrs Peabody slips on some ice; she falls and is taken to hospital, where her leg is X-rayed. In contrast to the first story, where Mrs Peabody's mental state forms the basis of the tale, the second scenario has no emotional content.
Professor Frith then questioned the two groups about the stories while measuring their brain activity. She found that when recalling the first story, the control group had extra activity at the front of the left side of the brain that the autistic group lacked. Autistic people cannot use the part of the brain that others use to speculate on what other people are thinking, she concluded.
Professor Frith also examined the autobiographies of some of the very few autistic people who have partially recovered from the disorder and written about their experiences as an autistic child. "There is evidence from these autobiographies that there was a lack of self-consciousness," Professor Frith said. The writings describe feeling like a subject under hypnosis and liken consciousness to sleep-walking and sleep-talking.
She said these people now have great difficulty coping with sensory overload: "They become hyper-aware and self-obsessed." This implies that the self-consciousness that these people have developed is not normal. Indeed, people who recover from autism cannot lead a normal social life.
The purpose of normal self-consciousness is creating and maintaining an ordinary social life, Professor Frith said. "Human beings not only have a profound interest in social interactions, they depend on them."