Sleep & Dreams: Cognitive Approach

Question 1

Crick and Mitchison’s theory (9)

Answer 1

• 1986 reorganisational theory of dreaming
• Computer modelling of neural networks to replicate the brain’s processing approach
• Role of creating schemas
• Brain actively processes information gained during the day
• Uses down-time with no new stimuli to organise the day’s information, i.e. mental processing occurs - discards useless information and keeps important information then adds it to the neural network
• Found memories can be easily overloaded, and they developed neural network computer models of learning
• Dreams are the side-effect of organising adaptive and parasitic memories
• The cortex becomes overloaded during the day and REM sleep helps create space in the memory and improves its organisation
• Sleep is for cognitive reorganisation - as unconnected memories and ideas are activated, a random selection of thoughts and memories form into a dream

Question 2

Czeisler date & aim (3)

Answer 2

• 1990
• To see whether shift workers’ circadian rhythms could adjust by solely altering light brightness
• To see if catastrophic accidents taking place in the early hours of the morning (e.g. Chernobyl) due to worker fatigue could be prevented

Question 3

Cognitive approach overview (8)

Answer 3

• Computer modelling used to explain and predict dreams and neural networks
• Sleep is necessary for effective information processing
• Sleep is needed in order to consolidate memories
• Sleep plays a role in problem solving
• Schemas (packets of knowledge) are adapted and developed during sleep
• During sleep, information comes in and is processed, and a response is produced
• Explains behaviour in terms of processing information
• Neural networks replicated in a computer programme

Question 4

Crick and Mitchison 1983 hypothesis (4)

Answer 4

• Reverse learning theory
• Brain gets rid of parasitic information
• Brain frees up space in finite cortex so cognitive processes can take place in the brain
• Dreaming enables forgetting to occur

Question 5

Evidence for Crick and Mitchison’s theory (1)

Answer 5

• Echidnas and dolphins have very large brains but don’t appear to have REM sleep - they can’t lose information so they store it away, hence their large brains are for capacity and not processing

Question 6

Schema (4)

Answer 6

• Way of understanding the world
• Packet of information
• Meaningful links through experience
• Can explain stereotypes

Question 7

Computer analogy (1)

Answer 7

• Input (environment) —> process —> output (response)

Question 8

Czeisler method (8)

Answer 8

• Ten studies, each over two weeks
• Eight male participants, all between ages of 22 and 29
• Blood and urine samples taken
• Temperatures measured
• Sleep logs kept
• Control and treatment experiments conducted
• Control group: participants worked during the night doing cognitive tasks with normal lighting for eight hours and slept in the day in a dark room for 8 hours
• Treatment group: participants worked during the night doing cognitive tasks with bright lighting for eight hours and slept during the day in a dark room for 8 hours

Question 9

Czeisler results (2)

Answer 9

• Control group study show no significant change - their circadian rhythms essentially haven’t adjusted
• Treatment study group’s circadian rhythms have adjusted as their normal body temperatures now match their new pattern of waking and sleeping hours - temperature is lowest at deepest stage of sleep, which for these men has switched from being at night to during the day, when they had to sleep

Question 10

Czeisler conclusion

Answer 10

• Aims were achieved
• Circadian rhythm can be changed just by manipulating light and dark