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1. B1c1 The Biological
Theory of Dreaming
THE ACTIVATION-SYNTHESIS THEORY OF DREAMING
WHAT SYNTHESIS IS
TERMS SUCH AS RANDOM ACTIVATION, SENSORY BLOCKADE AND MOVEMENT INHINITION

2. Hobson and McCarley 1977 Activation-
synthesis theory
Dreams are random messages in the brain being interpreted to make a story.
Messages are activated randomly, and then synthesised (put together) into a story.
Hobson and McCarley are biologist not psychologist.
Psychologist = look at the brain and behaviour, thoughts, emotions and personality.
Biologist = Look at the physical processes dealing with the brains behaviour.

3. Hobson and McCarley
Said that there is a dream state generator in the brain and it is this part of the brain that is
switched on during REM Sleep.

4. Stages of sleep
Research shows we go through about 5 cycles of 4 stages of sleep and after each cycle there is
REM Sleep.
REM (Rapid Eye Movement)sleep happens around 5 or more times a night.
As dreaming during REM sleep is easily recognisable, scientist can measure electrical brain
activity using an EEG. (electroencephalograph)
During REM sleep, any incoming information from the senses is blocked. This is known as
Sensory Blockade.
Physical movement is also blocked, This is know as Movement Inhibition.
So during REM Sleep the is no information coming into the brain and no outgoing movements
being made by the body.

5. REM Sleep
HOWEVER
During REM Sleep the neurons in the brain are activated because there are random impulses
that ‘give’ information as it were from the senses.
This is known as Random Activation and is the Activation part of Activation-synthesis.
The information that comes from inside the brain itself is known as internally-generated
information. The brain then tries to make sense of the ‘nonsense’ it has generated.
It is synthesising the information to make it into a story, and this is the ‘synthesis’ part of the
theory.

6. Copy down table into books from page
65. and answer questions.
Concepts in the activation-synthesis theory of dreaming
REM Sleep
Sensory blockade
Movement inhibition
Neurons
Random Activation
Synthesis