Sensation and Perception

1. Sensation and Perception Chapter 4

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5. Sensation and Perception • Sensation- the process of receiving information from the environment • Perception- the process of organizing sensory information and making it meaningful • Absolute Threshold- the level of sensory stimulation needed for sensation (and thus perception) to occur • Ex. A dim light in a well light room is barely visible, yet highly visible in a dark room • Ex. Slight ding is barely audible in a noisy room, yet highly audible in a quiet room

6. 100 Percentage of correct detections 75 50 Subliminal stimuli 25 0 Low Absolute threshold Medium Intensity of stimulus Sensation and Perception • Subliminal Perception (Subliminal Messages)- stimulation that is below our threshold and takes place below our level of consciousness • Watch clips of movies • Does subliminal advertising work?

7. Sensation and Perception • Weber’s Law- to perceive a difference between 2 stimuli, they must differ by constant proportion • Sensory Adaptation- diminished sensitivity with constant stimulation • Ex. Smell when you walk in a restaurant • Ex. Light in a movie theater

8. Whorff Hypothesis • Show list of colors and label the colors • List as many words for “love” as you can • List as many words for “snow” as you can • Whorff Hypothesis- the more words a culture has for something, the more they perceive it • Ex. Teenagers can think of many words for love • Ex. Eskimos have many words– we have only a few

9. Sensation- Vision Vision- sense of seeing White Light- light as it originates (off the sun or off a bulb) before it is broken into different frequencies

10. Vision cont

11. Vision cont • Cornea- clear outer covering of the eye • Pupil- adjustable opening in the eye • black circle • Gets larger in darkness to allow more light in, and smaller in brightness to keep light out • Iris- colored circular muscle that opens and closes the pupil • Lens- behind pupil to change shape and focus the image in the retina

12. Vision cont • Retina- inner surface in the back of the eye which contain million of receptors • Rods- visual receptor for black and white • Cones- visual receptors for color • Page 95 in the book Fire Truck • Fovea- central part of the retina where cones exist and images are projected • Optic Nerve- carries visual information to the brain for interpretation

13. Vision cont • Blind Spot- portion of the retina where the optic nerve exits the eye, and there are no rods and cones • Put hand over one eye, place other hand straight out at arms length and one finger up, move hand SLOWLY outward, finger will “disappear” • Page 94 in the book

14. Vision cont

15. Vision cont • Nearsightedness- see nearby objects more clearly • Farsightedness- see faraway objects more clearly • Color Blindness- inability to perceive certain colors such as red and green • Color blind test page 96

16. Vision cont • Afterimage- image that remains after stimulation of the retina has ended • Cones not used fire to bring the visual system back in balance Another afterimage activity on page 97

17. Vision • Opponent Processing Theory- opposing retinal processes enable color vision • Red – Green • Blue – Yellow • Black – White

18. Sensation- Hearing • Audition- sense of hearing • Pitch- how high or low a sound is • Depends on the frequency- how many times the wave passes through a point • Timbre- the complexity of a sound • Intensity- how loud a sound is • Decibels- measure of sounds intensity (loudness)

19. Hearing cont

21. Hearing cont • Eardrum- piece of skin stretched tightly over the entrance to the ear • Like a real drum • Sound waves hit the ear drum and vibrate, causing connected bones to vibrate • Cochlea- snail shaped part of the ear filled with liquid and small hairs • Cilia- hair cells in the cochlea that receive different frequencies • Like strings on a musical instrument • Auditory Nerve- bundle of nerves that carry sound from the ear to the brain

22. Sensation- Touch • Cutaneous Receptors- nerve receptors in the skin which respond to pressure, temperature, and pain • 3 Sensations of touch: • Pressure • Temperature • Pain

23. Sensation- Smell • Olfaction- the sense of smell • Olfactory bulbs- units that receive odor molecules and communicate their nature to the brain • Pheromones- odor chemicals that communicate a message

24. Olfactory nerve Olfactory bulb Receptor cells in olfactory membrane Nasal passage Smell cont

25. Number of correct answers Women and young adults have best sense of smell 4 Women 3 Men 2 0 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 Age Group Smell cont

26. Sensation- Taste • Taste Receptors- chemical receptors on the tongue that decode molecules of food or drink to identify them • 4 Sensations of Taste: • Salt • Sweet • Sour • Bitter

27. Sensations • Sensory Interaction- principle that one sense may influence another • Ex smell and taste regarding food