SENSATION AND PERCEPTION
SENSATION AND PERCEPTION
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SENSATION
- Awareness of physical changes
• MEASURING SENSATION 1. Absolute threshold - detection of signal 50 percent of time 2. Difference thresholds (j.n.d. - just noticeable difference) a. Difference in sensation detectable 50 percent of the time b. Weber's Law - change necessary for j.n.d. is a proportion or original stimulus • THE EYE 1. Light enters through the cornea 2. Lens focuses light on the retina 3. Retina - at the back of the eyeball a. Rods - respond to dim light b. Cones - respond to color c. Fovea - center of retina, contains only cones, site where vision is sharpest • THE EAR 1. Outer ear - collects sound waves 2. Middle ear - waves strike eardrum which passes them to three tiny bones which intensify the force of the vibrations 3. Inner ear - contains receptor cells (hair cells) located within the cochlea which initiate nerve impulses which travel to the brain • TASTE 1. Four basic tastes - Salty, sour, bitter and sweet - each associated with different receptors or taste buds! • SMELL 1. Receptors in mocous membrane of nasal passage • SKIN SENSES 1. Touch (pressure), warmth, cold and pain • PERCEPTION: Organization and interpretation of sensations 1. World seen as constant, although the sensation may change 2. Needs, beliefs, emotions, expectations and past experience all influence perception
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