These notes are compiled using the textbook, lecture notes, and study outcomes. They are easy to understand and include diagrams. All of the visual material used in the textbook and in lectures are also included.
1. Variations in levels of awareness
2. The evolutionary roots of consciousness
3. Consciousness and brain activity
→ Consciousness: the awareness of internal and external stimuli
○ Includes:
Your awareness of external events
Your awareness of internal sensation
Your awareness of yourself as the unique being having these experiences
Your awareness of your thoughts about these experiences
○ It is a personal awareness
○ Consciousness is constantly moving and flowing – William James called it the Stream of
Consciousness
1. Variations in Levels of Awareness
→ According to Freud = steam of consciousness has depth – what goes on in the unconscious
→ Conscious and unconscious processes have different levels of awareness
→ Freud – one of the first theorists to recognise the consciousness is not an all-or-none phenomenon
→ People continue to maintain some awareness during sleep and anaesthesia
○ Some stimuli can still penetrate awareness
Some patients can later repeat thing the surgeon said
While people are asleep – can still register external events to some degree
Selective sensitivity to sound = some mental processes during sleep must exist
2. The Evolutionary Roots of Consciousness
→ Plenty of debate about exactly how consciousness proved to be adaptive
→ Thought that consciousness helped our ancestors to think through courses of action + their
consequences
→ Little empirical evidence to judge merits of theories
3. Consciousness and Brain Activity
→ Consciousness does not arise from any distinct structure in the brain
○ Activity in distributed networks of neural pathways
→ EEG most commonly used to record brain activity (electroencephalograph)
○ Device that monitors the electrical activity of the brain – recording electrodes attached to the scalp
○ Summarised the rhythm of cortical activity in the brain in terms of line tracings (brainwaves)
○ Tracings vary in amplitude and frequency
Brain wave activity based on usually divided into 4
bands based on frequency of the brain waves:
Beta (13-24 cps) β
Normal waking thought, alert problem solving
Alpha (8-12 cps) α
Deep relaxation, blank mind, meditation
Theta (4-7 cps) θ
Light sleep
Delta (under 4 cps) Δ
Deep sleep
→ Different patterns of EEG activity = associated with different states of consciousness
Biological Rhythms and Sleep
1. The role of circadian rhythms
2. Ignoring circadian rhythms
→ Variations in consciousness – shaped in part by biological rhythms
→ Biological Rhythms: periodic fluctuations in physiological functioning
○ Organisms have “internal clocks” = monitor passage of time somehow
1. The Role of Circadian Rhythms
→ Circadian rhythms: the 24-hour biological cycles found in humans and many other species
→ In humans – circadian rhythms particularly influential in regulation of sleep
→ Daily cycles also produce rhythmic variations in:
○ Blood pressure
○ Urine production
○ Hormonal secretions
○ Other physical functions
→ Cycles also affect alertness, short-term memory, and other aspects of cognitive performance
3
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