The activation synthesis theory

1. Hobson and McCarley (1977) put forward activation synthesis, which explains a dream in two stages.
2. Activation is the random neural firing the brain produces during REM sleep.
3. Synthesis is the cerebral cortex making sense of that firing as though it were real experience.
4. Both stages happen inside REM sleep, the stage where the brain is at its busiest and where most dreaming occurs.
5. The two stages are one process seen at two levels, since the firing and the interpreting are going on at the same time through a REM period.

Activity of neurons in the pons

1. When you enter REM sleep, neurons in the pons become intensely active.
2. They fire in irregular bursts, with no steady pattern behind them.
3. Nothing outside the body triggers these bursts, so each one arrives with no built-in meaning.
4. One burst might be tied to movement and the next to a sound, in no particular order.
5. The pons sits in the brainstem, one of the brain's three main divisions alongside the cerebrum and the cerebellum.

Synthesis in the cerebral cortex

1. The cerebral cortex is the outer layer of the cerebrum, and it receives these scattered bursts as though they were real sensory input.
2. It draws on your stored memories and expectations to label each burst.
3. It then arranges the labelled bursts into a sequence that feels like one event following another.
4. That building of a coherent dream out of random signals is what synthesis means.
5. The cortex has only your own memories to work with, so a dream is built from familiar material even when the sequence makes no sense.

Criticisms

1. Strengths
   1. It rests on real, observable brain activity during REM sleep.
   2. Williams et al. (1992) found REM dream reports were more bizarre than waking fantasies, which is what random activation predicts.
   3. It makes testable predictions, so it counts as a scientific account of dreaming.
2. Weaknesses, and the reductionism and holism debate
   1. The theory is reductionist because it explains a rich experience through random brainstem firing alone.
   2. A holistic view says a dream can be meaningful and tied to the dreamer's waking life.
   3. Someone who dreams of missing the bus the night before every exam is describing a pattern that mirrors a real worry.
   4. It explains where dreams come from without saying what they are for.

Turning this into marks

1. When a strength and a weakness are both asked for, make them genuinely separate rather than giving two versions of reductionism.
2. Name the pons and the cerebral cortex, because writing that the brain produces signals and then interprets them does not secure the knowledge mark.
3. The mark most often lost is naming reductionism without saying what a holistic view adds, which is that a dream can be meaningful and tied to waking life.