July20_09 - 7/20/09 Consciousness The subjective experience...

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1 Psych 1 Principles of Psychology Dr. Emiliana Simon-Thomas 7/20/09 Consciousness The subjective experience of perceiving oneself and other entities Lags about 300 ms behind brain activity underlying the decision to perform a motor action at will. Lags about 100 ms behind a response in a reaction time task. Exists in varying degrees and in altered states: daydreaming, sleep, hypnotic states, chemically induced hallucinations, ‘near-death visions’, etc…. Circadian rhythms * Cycles of activity and inactivity that last about 1 day (24 hours) Our daily fluctuations in degrees of consciousness: wakefulness and sleep. Based on internal biological mechanisms and responses to external input (light, temperature, noise etc. .) People put in caves (no cues for day vs. night) still sleep and wake at about the same times over the course of a day. Mechanisms in the brain rely on light to reset your body’s clock and keep it in step with the environment. * Ultradian (shorter) & infradian (longer) rhythms Circadian Rhythms The body s internal clock: the suprachiasmatic nucleus of the hypothalamus Circadian Rhythms The body s endogenous clock: the suprachiasmatic nucleus of the hypothalamus . Receives direct input from light sensitive cells in the retina. Remove it and sleep cycles become erratic. Put it into a petri dish and it s cells continue to fire in a circadian fashion. It regulates the release of melatonin by the pineal gland. Sleep: why do we do it? Why Sleep? Sleep deprivation causes irritability, fatigue, impaired concentration, depressed immune system, greater vulnerability to accidents. 2. Evolutionary/Energy Conservation theory Sleep requires less energy and protects diurnal creatures from their ineffectiveness in the dark. 3. Growth theory 4. Memory Consolidation theory Evidence suggests that people perform better on memory tasks if ample sleep occurs between the encoding and retrieval.
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2 The Sleep Cycle 0 1 2 3 4 5 6 7 4 3 2 1 Sleep stages Awake Hours of sleep REM About every 90-100 minutes, we pass through an ultradian cycle
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July20_09 - 7/20/09 Consciousness The subjective experience...

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