Published on January 15, 2010
SENSATION AND PERCEPTION : SENSATION AND PERCEPTION Sensation and Perception : Sensation and Perception Detecting, Processing and Interpreting Experiences Sensory Receptors Sensory Thresholds Habituation and Sensory Adaptation The Sensory Organs Perceiving Sensory Stimuli Slide 6: SENSATION the process of receiving stimulus energies from the external environment sensory organs: eyes (visual system) ears (auditory) nose (olfactory) tongue (gustatory) skin (tactile) Slide 7: PERCEPTION the process of organizing and interpreting sensory information to give it meaning. Prior experiences Expectations Memory Biases Why is it important to study sensation and perception? : Why is it important to study sensation and perception? The purpose of perception is: 1) to represent information from the outside world internally; 2) adaptation that improves a species’ chances for survival; and 3) to help in designing devices to restore perception to those who have lost some (or all) and also to devise treatments for other perceptual problems. Slide 9: Have you ever experienced (or seen someone) bumping into a clear window glass because you did not know that it was there? Slide 10: BOTTOM-UP PROCESSING TOP-DOWN PROCESSING Sensory receptors register information about the external environment and send it up to the brain for analysis and interpretation. Starts out with cognitive processing at the higher levels of the brain. Cognitive processes include knowledge, beliefs and expectations. Slide 11: JIGSAW PUZZLE SENSORY RECEPTORS : SENSORY RECEPTORS All sensation begins with sensory receptors. Sensory receptors are specialized cells that detect and transmit stimulus information to sensory nerves and the brain. SENSORY THRESHOLDS : SENSORY THRESHOLDS Buzzing mosquito? Difference between regular Coke and Coke Zero? SENSORY THRESHOLDS : SENSORY THRESHOLDS Absolute threshold Difference threshold Minimum amount of energy that a person can detect just noticeable difference (jnd) the degree of difference that must exist between two stimuli before the difference is detected. SENSORY THRESHOLDS : SENSORY THRESHOLDS Absolute Threshold Orange juice One tablespoon? Two tablespoon? Three tablespoon! Watching TV while your roommate is sleeping. Volume? Slide 16: Approximate Absolute Thresholds : Approximate Absolute Thresholds Vision A candle flame at 30 miles on a dark, clear night. Hearing A ticking watch at 20 feet under quiet conditions. Smell One drop of perfume diffused throughout 3 rooms Taste A teaspoon of sugar in 2 gallons of water Touch The wing of a fly falling on your cheek from a distance of one centimeter. Slide 18: Difference Threshold Watching TV while your roommate is sleeping. Your roommate, suddenly wakes-up. Also wants to watch the TV! Volume? Slide 19: Slide 20: A student late for his class. 10: 03 – late? 10:05 – late? 10: 10 – late? 10:15 – late!!! It takes 15 minutes for a student to be detected as late. Absolute or difference threshold? *Depends on the individual who perceives and the condition of the environment. Slide 21: Subliminal Perception the ability to detect information below the level of conscious awareness. JAMES VICARY (1957) “Eat Popcorn”; “Drink Coke” .003 second once every 5 secs. The sales of popcorn and coke increased! HOAX! Subliminal perception does not work in advertising. HABITUATION AND SENSORY ADAPTATION : HABITUATION AND SENSORY ADAPTATION The lower centers of the brain sort through sensory stimulation and “ignore” or prevent conscious attention to stimuli that do not change. Sound of aircon Smell of garbage Reading your readings? Slide 23: Sensory adaptation The sensory receptor cells become less responsive to an unchanging stimulus. The receptors are no longer sending signals to the brain. Habituation - The sensory receptor cells are still responding to the stimulus, but the lower centers of the brain are not sending the signals from those receptors in the cortex. Slide 24: QUESTIONS?