The Activation-Synthesis Model of Dreaming: A Physiological Perspective on Dream Interpretation

Introduction to the Activation-Synthesis Model

The activation-synthesis model of dreaming was proposed in 1977 by Robert McCarley and J. Allan Hobson of Harvard Medical School. This model examines the purely physiological correlates of dreaming. Hobson and McCarley believed they had put forward a hypothesis that refuted the notion that dreams are meaningful, especially as this notion was formulated by Sigmund Freud and propagated through his tradition of dream interpretation.

Activation Stage: Electrical Signals in the Brain During REM Sleep

During rapid eye movement (REM) sleep, the stage most closely associated with dreaming, a portion of the brain called the pons (located in the primitive hindbrain) generates electrical signals. These signals are sent to various brain areas, including those responsible for motor activities, sensory activities, and conscious thought. Hobson and McCarley hypothesized that these signals send essentially random images, feelings, and sensations to the higher mental centers of the forebrain. This is known as the “activation” stage of their theory.

Synthesis Stage: Creating Meaning from Random Signals

In normal waking consciousness, the forebrain processes various types of sensory input to create a meaningful experience of the world. Faced with a flood of disconnected inputs during REM sleep, the brain attempts to impose order on the incoming messages, thereby constructing whatever narrative structure dreams have. This is the “synthesis” stage of the theory. However, many dreams remain a collection of incoherent images, representing groups of signals that the brain could not fully synthesize.

Criticism of the Activation-Synthesis Model

For individuals frustrated by the complexity of Freudian or other schools of dream interpretation, the activation-synthesis theory may seem appealing because it dismisses dreams as random and nonsensical. However, because many people have experienced insightful dreams, the theory is ultimately unsatisfying. Additionally, on a purely physiological level, the theory is incomplete because it does not account for dreams that occur during non-REM sleep.