Perception & Sensation

Average Sleep Hours: Percentage of people and number of hours of sleep in a night. - 0% of people report 0 hours. - 10% of people sleep 2-4 hours. - 20% of people sleep 5-6 hours. - 30% of people sleep 7-8 hours. - 40% of people sleep 9-10 hours.

Definition: Our awareness of various cognitive processes including sleeping, being awake, etc.
States of Consciousness: - Coma - General Anesthesia - Lucid Dreaming - Drowsiness - Conscious Wakefulness - REM Sleep - Light Sleep - Deep Sleep - Minimally Conscious State - Vegetative State

Definition: 24-hour sleep/awake cycle regulating sleep and other body functions such as blood pressure and body temperature.
Disruptions: Jet lag and shift work can cause internal clock misalignment with current time zone.

Dreaming Dynamics: - REM Sleep: More dreams occur throughout the night, with varying depth of sleep. - REM: Rapid eye movement, dreaming state. - NREM: Non-REM; typically more found in the earlier parts of sleep.
Hypnagogic Sensations: Feelings of falling that occur during NREM1. - Paradoxical Sleep: REM sleep where the brain is active and awake while the somatic nervous system remains paralyzed, resulting in a relaxed body.

Definition: Following sleep deprivation, stress, or drug use, an increase in REM sleep duration is observed, implying a biological necessity for REM sleep.

Freudian and Jungian Thoughts: Based on old theories with no scientific support.
Manifest Content: The visible aspect of dreams.
Latent Content: The underlying meaning of dreams.
Activation-Synthesis Hypothesis: - Best explanation: limbic system and brain stem release random bursts of energy during sleep to clean up the brain, with dreams being the brain's narrative construction based on this activity.
Consolidation Dream Theory: - Similar to Activation-Synthesis, focusing on memory processing and consolidation during sleep.

Functions: - Consolidation: Enhances memory retention of daily experiences. - Restoration: Regenerates and repairs the body’s resources, such as energy levels and immune system function.

Consequence of Interruptions: - Sleep interruptions can result in: - Memory impairment - Physical impairment
- Behavioral impairments

Somnambulism (Sleep Walking): - Occurs during NREM 3, caused by fatigue, stress, or substance use.
REM Behavior Disorder: - Malfunction affecting the paralysis usually present during REM sleep.
Insomnia: - Difficulty in falling asleep or staying asleep, often due to worry or anxiety.
Narcolepsy: - Sudden onset of REM sleep, often treated with prescription stimulants.
Sleep Apnea: - Brief stoppage of breathing during sleep, caused by genetic factors, obesity, or flawed breathing mechanisms.

Basic Principles of Sensation: - Sensation: The process of receiving stimulus energies from the external environment. - Transduction: Transforming physical energy into electrochemical energy (action potentials). - Perception: Organizing and interpreting sensory information.

Absolute Threshold: The minimum energy level required for detection 50% of the time. - Noise: Competing and irrelevant stimuli impacting detection ability.
Difference Threshold: - Operates under Weber’s Law: Two stimuli must differ by a constant percentage to be perceived as different.

Selective Attention: Choosing to focus on specific stimuli while ignoring others. - Inattentional Blindness: Missing background information due to concentrated focus (e.g., gorilla experiment). - Change Blindness: Unawareness of subtle changes in a scene (e.g., Whodunnit). - Divided Attention: Splitting attention between multiple stimuli, leading to failures in noticing certain elements.
Cocktail Party Effect: Filtering out irrelevant information while remaining open to important stimuli.

Key Components: - Sclera - Retina - Iris - Cornea - Pupil - Lens - Fovea - Optic Nerve
Functions: - Lens: Adjusts curvature for focusing using visual accommodation. - Retina: Contains photoreceptors; fovea provides sharpest vision (visual acuity). - Rods: Approx. 120 million; for black and white vision, low light functionality. - Cones: Approx. 6 million; for color vision; operate best under bright conditions.
Blind Spot: Lacks rods and cones; where the optic nerve exits.

Trichromatic Theory: Three types of cones (Blue, Green, Red) work together; activity ratio forms color perception.
Opponent-Process Theory: Three opposing ganglion cell pairings (blue-yellow, red-green, black-white); overactivation results in afterimages. - Importance in color blindness cases; linked to deficiencies in cones or ganglion cell damage.

Kinesthesis: System for body position awareness through receptors in joints, tendons, and muscles.
Vestibular System: Inner ear components contributing to balance via semicircular canals.
Chemical Senses: Includes smell (olfaction), processed by the olfactory system, and taste (gustation), with receptors for six taste qualities: sweet, sour, bitter, salty, umami, and oleogustus.
Sense Interaction: Taste largely influenced by smell and other sensory inputs; significant impact on overall taste perception.

Definition: Diminished sensitivity as a consequence of constant stimulation of sensory receptors.

Description: A condition where sensory modalities are mixed, enabling individuals to perceive sounds in colors or taste shapes. Exact causes remain unclear but involve atypical brain signaling processes.