Chapter Three: Consciousness And The Two-Track Mind

Late 1800's psychology was "the description and explanation of states of consciousness." -20th century scientific study of psychology was difficult-influenced by "behaviorism"-scientists began studying consciousness based on "direct observation and behavior." -Late 1960's-advanced in neuroscience allowed study of brain activity during, sleep, dream state, and other mental states; and consciousness altered hypnosis and drugs. -Psychologists put emphasis on "cognition", or mental process. -Psychologist NOW define consciousness as "an awareness of ourselves and our environment." Science explores BIOLOGY of consciousness.

our awareness of our environment and ourselves

Cognitive neuroscientists and others studying the brain mechanisms underlying consciousness and cognition have discovered a two-track human mind, each with its own neural processing. This dual processing affects our perception, memory, and attitudes at an explicit, conscious level and at an implicit, unconscious level.

the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language)

the principle that information is often simultaneously processed on separate conscious and unconscious tracks

a condition in which a person can respond to a visual stimulus without consciously experiencing it

We selectively attend to, and process, a very limited aspect of incoming information. We even display Inattentional blindness, blocking out events and changes in our visual world. Shifting the spotlight of our attention from one thing to another contributes to car and pedestrian accidents.

the focusing of conscious awareness on a particular stimulus

failing to see a visible object when our attention is directed elsewhere

failing to notice changes in the environment

We cycle through five sleep stages in about 90 minutes. leaving the alpha waves of the awake. relaxed stage, we descend into transitonal stage 1 sleep, often with the sensation of falling or floating. -stage 2 sleep ( in which we spend the most time) follows about 20 minutes later, with its characteristic sleep spindles. -Then follow stages 3 and 4, together lasting about 30 minutes, with large, slow delta waves. Reversing course, we retrace our path, but with one difference: We experience periods of REM (rapid eye movement) sleep. -Most dreaming occurs in this 5th stage (also known as paradoxical sleep) of internal arousal but outward paralysis, During a normal night's sleep, periods of Stage 3 and 4 sleep shorten and REM sleep lengthens

the biological clock; regular body rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle

Our internal biological rhythms create periodic physiological fluctuations. The circadian rhythm's 24-hour cycle regulates our daily schedule of sleeping and waking, in part in response to light on the retina. Shifts in schedules can reset our biological clock.

rapid eye movement sleep, a recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active

the relatively slow brain waves of a relaxed, awake state

periodic, natural, reversible loss of consciousness - as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation

false sensory experiences such as seeing something in the absence of an external visual stimulus

the large, slow brain waves associated with deep sleep

Arousal from sleep occurs when light activates our circadian clock. This occurs when light sensitive proteins trigger signals in the brains SCN which stimulates the pineal gland, decreasing production of sleep hormone melatonin. The rise and fall of the sun during the day naturally stimulates these processes and determines our sleeping patterns. Artificial light has altered our sleep.