What’s the difference between sensation and perception?

1. What’s the difference between sensation and perception?

2. Do We have 5 senses? • Sight • Hearing • Taste • Touch • Smell • What about… temperature? Balance? Movement?

3. How does it work? Sense receptors (specialized cells – some in the ears, some in the eyes, some on the tongue…) FIRE to stimulate sensory NEURONS which stimulate specialized paths to specialized areas of the brain (visual cortex, auditory cortex, etc) so…. Sense receptors convert physical energy (touch, heat, light) to electrical energy

4. How does it work? …if we could stimulate the visual cortex of a blind person, would they be able to see? Well… probably, yes. Ptito (2005) – connects pattern detector to electrodes on tongue which stimulate visual areas of brain.

5. Synesthesia* Something similar happens naturally to some people. Sounds have taste or color. Colors have scents or tastes. One synesthete who attended an orchestra concert as a child thought the lights were lowered so the audience could see the colors better!!!!!!!!! *A fun and interesting paper topic!!

6. Can you believe everything you see? Do you see everything there is to see? No, and no. • “Visible” light – we see only certain ranges of wavelength • Audible sound – other animals hear much different ranges of pitch We “ build” perceptions from our sensations.

7. How do we perceive waves?

8. From the eye to ‘seeing’ • Retina: Back of the eye – location of visual sense receptors. Lens reflects images upside down onto the retina • Rods: Sensitive, but not to color; concentrated in the periphery • Cones: Sense color; concentrated in the center of the eye

9. chapter 6 Structures of the retina

10. From the eye to ‘seeing’ Once in the cortex, we construct what we’re seeing. A few years ago, neurologists demonstrated the existence of a Halle Berry neuron. Many years ago, Huble & Wiesel (1968) paved the way for this work: showing that particular cells they termed “feature detectors” fired for particular patterns, such as a line at a particular angle.

11. chapter 6 Gestalt principles Proximity Things close to one another are grouped together Closure The brain tends to fill in gaps to perceive complete forms

12. chapter 6 Gestalt principles Similarity Things that are alike are perceived together Continuity Seeing continuity in lines that could be interpreted as either continuous or abruptly shifting in direction.

13. chapter 6 Depth and distance perception Binocular cues: visual cues that require the use of both eyes Convergence Turning inward of the eyes, which occurs when they focus on a nearby object Retinal disparity The slight difference in lateral separation between two objects as seen by the right and left eyes

14. chapter 6 Depth and distance perception Monocular cues: visual cues that require just one eye Interposition: If you are blocking my view of the car, you must be closer Linear perspective: We are fooled by this in the Muller-Lyer Illusion Size constancy: Why does the moon appear so much larger when it’s near the horizon?

15. chapter 6 The Müller-Lyer illusion

16. chapter 6 Visual constancies The accurate perception of objects as stable or unchanged despite changes in the sensory patterns they produce Shape constancy: A pie is always round even when it’s an arc on the retina Location constancy: We see objects as still even though their image on the retina moves as we move Size constancy: We see objects as staying the same size even though they grow smaller on the retina Brightness constancy: We see snow as white on a cloudy day when the waves’ amplitude may send a different message Color constancy: We see an object’s color as the same in different light, even though the reflected wavelength changes

17. How do we hear? • Remember – sense receptors translate physical (sound waves) to electrical (neural impulse) • Ear drum? No. • Hammer, anvil, stirrup bones? No. • All the way inside the cochlea – hair cells. • NOTE! These are VERY fragile cells. Your MP3 player, your job, or one concert could all cause permanent hearing loss.

18. How do we hear? • Gestalt principles apply to hearing, too • Proximity • Continuity • Similarity All help us know what sounds go together, and which sounds are the ‘background noise’

19. Taste How might taste help us survive? • Sweet • Sour • Bitter • Salty • Umami(?!)

20. Taste Where are the sense receptors for taste? • Inside the papillae (you can see these on your tongue) inside the taste buds • How many taste buds do you have? • 500 for some people • 10,000 for others • Who has more? The person who loves jalapenos or the person who cries when they get one?

21. Is there a connection between smell and taste? Many foods (chocolate, for one!) have almost no distinguishable taste without smell. Smell is a much more sensitive sense. • Specialized cells – sense receptors – millions of them – and there are about 1,000 different types! Each responds to a different part of a molecule’s structure.

22. Can you think of a category or type of smell? • We have salty, sweet, bitter, etc for taste. What about smell?

23. Where does pain come from? Where does it go? Is pain a sense? • Sometimes we feel pain where there is no damage • Sometimes there is damage where we feel no pain • Sometimes we feel pain where there is nothing at all Do we feel only the pain we need to feel?

24. Where does pain come from? Where does it go? • Multiple sets of neurons are involved in inhibiting or allowing pain signals to travel to the brain • The brain sometimes sends its own messages to these neurons What might be the benefit to the brain of “controlling” pain?

25. One more sense… for now • Sometimes pain comes from within the body • “Kinesthesis” always comes from inside the body • What messages do you need from your body in order to walk? • Semicircular canals in the ear provide information for “equilibrium” – our sense of balance • Other info you need?

26. How do our perceptual tricks develop? • Both inborn and learned • Feature detector cells can lose their functionality if they are not used (Blakemore & Cooper’s 1970 study of cats) • Infants won’t cross “visual cliff” at 6 months, and seem to notice the difference at 2 months • If vision or hearing are restored to a blind or deaf person after infancy, perceptual skills develop only to a limited degree (“critical periods” for experience to create learning)

27. Are our perceptual tricks universal? More evidence of learning • Experience: What is common in your environment • Needs/desires: Hungry? You’ll be the first to see the picture of food • Beliefs: UFO sightings, Mother Theresa french toast • Emotions: Influence pain perception among others (what do you see in the dark when you’re afraid?) • Expectations: Where is the typo in ths sentence? All influence what we “see”

28. Can you perceive without sensing? • What if a picture is flashed too quickly for you to ‘see’ it? Image can influence opinions/memory • What if you are asleep and listening to a “Learn to Relax” or “Improve Your Memory” tape? Placebo effect! Whichever tape you think you’re listening to, that is the skill that will improve. • ESP? Many, many efforts to demonstrate: well-designed studies fail. (Poorly designed studies succeed.) Remember the influence of beliefs and expectations? These probably explain most incidents of ESP.