Monday, July 18, 2011

Dreaming and Consciousness

The Stuff that Dreams are made of by John Anster Fitzgerald, 1858
The Stuff that Dreams are made of by John Anster Fitzgerald, 1858

By Stephen LaBerge, Ph.D.

Whether awake or asleep, our consciousness functions as a model of the world constructed by the brain from the best available sources of information. During waking conditions, this model is derived primarily from sensory input, which provides the most current information about present circumstances, and secondarily from contextual and motivational information. While we sleep, very little sensory input is available, so the world model we experience is constructed from what remains, contextual information from our lives, that is, expectations derived from past experience, and motivations (e.g., wishes, as Freud observed, but also fears). As a result, the content of our dreams is largely determined by what we fear, hope for, and expect.

From this perspective, dreaming can be viewed as the special case of perception without the constraints of external sensory input. Conversely, perception can be viewed as the special case of dreaming constrained by sensory input. Whichever way one looks at it, understanding dreaming is central to understanding consciousness. 

Theories of consciousness that do not account for dreaming must be regarded as incomplete, and theories that are contradicted by the findings of phenomenological and psycho-physiological studies on dreaming must be wrong. For example, the behaviorist assumption that "the brain is stimulated always and only from the outside by a sense organ process" cannot explain dreams; likewise, for the assumption that consciousness is the direct or exclusive product of sensory input. 

Dreaming experience is commonly viewed as qualitatively distinct from waking experience. Dreams are often believed to be characterized by lack of reflection and inability to act deliberately and with intention. However, this view has not been based on equivalent measurements of waking and dreaming state experiences. To achieve equivalence, it is necessary to evaluate waking experience retrospectively, in the same way that dreams are evaluated. In a recent study of this type, we found that compared to waking experiences, dreaming was more likely to contain public self consciousness and emotion, and less likely to contain deliberate choice. But it is notable that significant differences between dreaming and waking were not evident for other cognitive activities, and none of the measured cognitive functions were typically absent or rare in dreams. In particular, nearly identical levels of reflection were reported in both states. 

Although we are not usually explicitly aware of the fact that we are dreaming while we are dreaming, at times a remarkable exception occurs, and we become reflective enough to become conscious that we are dreaming. During such "lucid" dreams it is possible to freely remember the circumstances of waking life, to think clearly, and to act deliberately upon reflection or in accordance with plans decided upon before sleep, all while experiencing a dream world that seems vividly real. A series of studies to be summarized demonstrates that lucid dreamers can remember to perform predetermined actions and signal to the laboratory, allowing the derivation of precise psycho-physiological correlations and the methodical testing of hypotheses regarding consciousness in sleep.