Chapter 5 Sensation and Perception

1. Chapter 5Sensation and Perception

2. Sensation and Perception Sensation: is the process through which the senses pick up visual, auditory, and other sensory stimuli and transmit them to the brain. Perception: the process by which the brain actively organizes and interprets sensory information. They are interactive: sensation provides the data for perception, but perceptual processes influence sensation.

3. Absolute Threshold Absolute Threshold: the minimum about of sensory stimulation that can be detected 50% of the time. If you are listening to music, the very fact that you can hear it means that the absolute threshold has been crossed. But how much must the volume be turned up or down for you to notice a difference?

4. Difference Threshold Difference Threshold: the smallest difference between two stimuli that can be detected half the time Just Noticeable Difference [JND]: the smallest change in sensation that a person is able to detect at 50% of the time. If you were holding a 5-pound weight and 1-pound weight was added, you could easily notice the difference. But if you were holding 100-pounds and 1 additional pound was added, you could not sense the difference in weight. WHY NOT?

5. Weber�s Law Weber�s Law: the law stating that JND for all the senses depends on a proportion or percentage of change in the stimulus rather than on a fixed amount of change. For people to really perceive a difference, the stimuli must differ by a constant "proportion" not a constant "amount". According to Weber�s Law, the greater the original stimulus, the more it must be increased or decreased for the difference to be noticeable.

6. Sensory Receptors Would you be surprised to learn that our eyes do not actually see and that our ears do not hear? Remember: specific clusters of neurons in specialized parts of the brain must be stimulated for us to see, hear, taste, and so on. Yet the brain itself cannot respond directly to light, sound waves, odors, and tastes. How, then, does it get the message? The sense organs provide only the beginnings of sensation, which must be completed by the brain.The sense organs provide only the beginnings of sensation, which must be completed by the brain.

7. Sensory Receptors: Transduction Sensory Receptors: highly specialized cells in the sense organs that detect and respond to one type of sensory stimulus---light, sounds, odor, so on. Transduction: the process which sensory receptors convert the sensory stimulation into neural impulses. The neural impulses are then transmitted to precise locations in the brain, such as the primary visual cortex for vision or the primary auditory cortex for hearing. We experience a sensation only when the appropriate part of the brain is stimulated. The sensory receptors provide the essential link between the physical sensory world and the brain.The sensory receptors provide the essential link between the physical sensory world and the brain.

8. Sensory Receptors: Sensory Adaptation After time, the sensory receptors grow accustomed to constant, unchanging levels of stimuli---sights, sounds, or smells---so we notice them less and less, or not at all. For example, smokers become accustomed to the smell of cigarette smoke in their homes and on their clothing. Sensory Adaption: the process by which sensory receptors grow accustomed to constant, unchanging levels of stimuli over time.

9. Our eyes respond only to visible light waves, which form a small subgroup of electromagnetic waves, a band called the visible spectrum. These waves are measured in wavelengths, the distance from the peak of one wave to the peak of the next. The shortest light waves we can see appear violet, while the longest visible waves appear red.

10. Eye Cornea: the tough, transparent, protective layer that covers the front eye and beds the light rays inward through the pupil. Pupil: small opening that admits light. Iris: colored part of the eye that controls pupil. Retina: the layer of tissue that is located on the inner surface of the eyeball and contains the sensory receptors for vision. Lens: transparent disc-shape structure behind the iris/pupil that changes shape as it focuses on objects at varying distances. Fovea: small area at the center of retina that provides the clearest/sharpest vision bc it has the largest concentration of cons. Blind Spot: the point in each retina where there are no rods or cones bc the cable of ganglion cells is extending through the retinal wall. Optic Nerve: nerve that carries visual information from each retina to both sides of the brain.

11. Lens: Accommodation The lens performs the task of focusing on viewed objects. It flattens as it focuses on objects at a distance and becomes more spherical, bulging in the center, as it focused on close objects. This flattening and bulging action of the lens is known as accommodation. With age, the lens loses the ability to change its shape to accommodate for near vision, a condition called presbyopia (�old eyes�). This is why may people over the age of 40 must hold a book or newspaper at arm�s length or use reading glasses to magnify the print.

12. Receptor Cells Rods: are light-sensitive receptor cells in the retina that look like slender cylinders and allow the eye to respond to as few as five photons of light. Cones: are light-sensitive receptor cells in the retina that enable humans to see color and fine detail in adequate light but do not function in very dim light. At the back of the retina is a layer of light sensitive receptor cells, the rods and cons.At the back of the retina is a layer of light sensitive receptor cells, the rods and cons.

13. Light/Dark Adaptation Rhodopsin:: is a substance present in the rods that enable us to adapt to variations in light. It has two components: 1) opsin 2) retinal In bright light, opsin and retinal break apart, as the process of light adaptation takes place. During dark adaptation, opsion and retinal bind to one another, re-forming rhodopsin. For example, when you move from bright light to total darkness, you are momentarily blind until the opsion and retinal recombine.

14. How does visual information get from the retina to the primary visual cortex? The brain is responsible for converting the upside-down retinal images into meaningful visual information. But the first stages of neural processing actually take place in the retina itself.

15. When the light rays reach the sensory receptors (the rods and cones), the receptors transduce them to neural impulses. The impulses are then transmitted to the bipolar, amacrine, and horizontal cells, which carry them to the ganglion cells. The axon-like extensions of the ganglion cells are bundled together in a cable that extends through the wall of the retina, leaving the eye and leading to the brain. There are no rods or cones where the cable runs through the retinal wall, so this point is a blind spot in each eye. Beyond the retinal wall of each eye, the cable becomes the optic nerve, which carries visual information from each retina to both sides of the brain. At the optic chiasm, the two optic nerves come together, and some of the nerve fibers from each eye cross to the opposite side of the brain. They synapse with neurons in the thalamus, which transmit the neural impulses to the primary visual cortex, the part of the brain in which visual information is processed. Feature detectors are neurons in the brain that respond only to specific visual patterns (for example, to lines or angles).

16. Color Vision The perception of color results from the reflection of particular wavelengths of the visual spectrum from the surfaces of objects. For example, an object that appears to be red reflects light of longer wavelengths than one that appears to be blue. Researchers have identified three dimensions of light that combine to provide the rich world of color we experience: hue, saturation, and brightness.

17. Color Vision Hue: the dimension of light that refers to the specific color perceived (such red, green, and blue) Saturation: the purity of a color; a color becomes less pure as other wavelengths of light mix with it Brightness: the intensity of the light energy that is perceived as a color; based on the amplitude of the color�s light wave

18. Theories of Color Vision The theory of color vision suggesting there are three types of cones in the retina and that each type makes a maximal chemical response to one of three colors�green, blue, or red. Opponent-Process Theory The theory of color vision suggesting that three kinds of cells respond by increasing or decreasing their rate of firing when different colors are present. The red/green cells increase their firing rate when red is present and decrease it when green is present. Two major theories that attempt to explain color vision are the trichromatic theory and the opponent-process theory (next slide). Two major theories that attempt to explain color vision are the trichromatic theory and the opponent-process theory (next slide).

20. Afterimage Afterimage: a visual sensation that remains after a stimulus is withdrawn. Steadily fixate on the black light bulb for thirty seconds or more. Try not to avert your gaze. Immediately turn your gaze to the white region on the right adjoining the bulb (or a blank white sheet of paper). You should see a glowing light bulb!

21. The glowing white light bulb you see on the white screen after staring at the black light bulb figure is called an afterimage. When you focus on the black light bulb, light sensitive photoreceptors (whose job it is to convert light into electrical activity) in your retina respond to the incoming light.� Other neurons that receive input from these photoreceptors respond as well. As you continue to stare at the black light bulb your photoreceptors become desensitized (or fatigued).����� Your photopigment is "bleached" by this constant stimulation. The desensitization is strongest� for cells viewing the brightest part of the figure, but weaker for cells viewing the darkest part of the figure. Then, when the screen becomes white, the least depleted cells respond more strongly than their neighbors, producing the brightest part of the afterimage: the glowing light bulb. This is a negative afterimage, in which bright areas of the figure turn dark and vice versa. Positive afterimages also exist. Most� afterimages last only a few seconds to a minute,� since in the absence of strong stimulation, most nerve cells quickly readjust.

22. Color Blindness Color Blindness: the inability to distinguish certain colors from one another. About 8% of males experience some kind of difficulty in distinguishing colors, most commonly red from green. By contrast, fewer than 1% of females suffer from color blindness. Research shows that color blindness can have degrees.

23. Sound Frequency: the number of cycles completed by a sound wave in one second, determining the pitch of the sound; expressed in the unit called hertz (Hz). Pitch: is how high or low the sound is and is chiefly determined by frequency. The higher the frequency (the more cycles per second), the higher the sound. Amplitude: is the measure of loudness of a sound; expressed in the unit called decibel (dB). Each increase of 10 decibels makes a sound 10 times louder. Timbre: the distinctive quality of a sound that distinguishes it from other sounds of the same pitch and loudness.

24. Decibel Levels of Various Sounds A normal conversation at 3 feet measures 60 decibels, a soft whisper is 20 decibels. Any exposure to sounds of 130 decibels or higher puts a person at immediate risk for hearing damage. But levels as low as 90 decibels can cause hearing loss if one is exposed to them over long periods of time.

25. Ear and Hearing Audition: is the sensation and process of hearing. Outer Ear: the visible part of the ear, consisting of the pinna and the auditory canal. Middle Ear: the portion of the ear containing the ossicles, which connect the eardrum to the oval window and amplify sound waves. Inner Ear: the innermost portion of the ear, containing the cochlea, the vesicular sacs, and the semicircular canals,. Cochlea: the fluid-filled, snail shaped bony chamber in the inner ear that contains the basilar membrane and its hair cells (the sound receptors) Audition is the sensation and process of hearing. The outer ear is the visible part of the ear, consisting of the pinna and the auditory canal. Sound waves enter the pinna and travel to the end of the auditory canal, causing the eardrum to vibrate. This sets in motion the ossicles (hammer, anvil, and stirrup) in the middle ear, which connect the eardrum to the oval window and amplify the sound waves. The vibration of the oval window causes activity in the inner ear, setting in motion the fluid in the cochlea. The cochlea is a fluid-filled, snailshaped, bony chamber in the inner ear that contains the basilar membrane and its hair cells (the sound receptors). The moving fluid inside the cochlea pushes and pulls the hair cells attached to the thin basilar membrane, which transduce the vibrations into neural impulses. The auditory nerve then carries the neural impulses to the brain. Audition is the sensation and process of hearing. The outer ear is the visible part of the ear, consisting of the pinna and the auditory canal. Sound waves enter the pinna and travel to the end of the auditory canal, causing the eardrum to vibrate. This sets in motion the ossicles (hammer, anvil, and stirrup) in the middle ear, which connect the eardrum to the oval window and amplify the sound waves. The vibration of the oval window causes activity in the inner ear, setting in motion the fluid in the cochlea. The cochlea is a fluid-filled, snailshaped, bony chamber in the inner ear that contains the basilar membrane and its hair cells (the sound receptors). The moving fluid inside the cochlea pushes and pulls the hair cells attached to the thin basilar membrane, which transduce the vibrations into neural impulses. The auditory nerve then carries the neural impulses to the brain.

26. Ear Pinna: curved flaps of cartilage and skin attached to sides of head. (outer ear) Semicircular Canals: fluid-filled tublar canals that sense the rotation of the head (inner ear) Cochlea: long, coiled tube lined with sensory receptors called hair cells (inner ear) Auditory Canal: hair-lined tube through which sound travels. (outer ear) Eardrum: flexible membrane that vibrates in response to sound waves. Ossicles: small bones named for their shapes; hammer, anvil, stirrup (middle ear) Oval Window: membrane that transmits vibrations from ossicles to cochlea (middle ear) Auditory Nerve: nerve that transmits electrical impulses generated by hair cells in the cochlea to the brain

27. Ear and Hearing The outer ear is the visible part of the ear, consisting of the pinna and the auditory canal. Sound waves enter the pinna and travel to the end of the auditory canal, causing the eardrum to vibrate. This sets in motion the ossicles (hammer, anvil, and stirrup) in the middle ear, which connect the eardrum to the oval window and amplify the sound waves. The vibration of the oval window causes activity in the inner ear, setting in motion the fluid in the cochlea. The cochlea is a fluid-filled, snailshaped, bony chamber in the inner ear that contains the basilar membrane and its hair cells (the sound receptors). The moving fluid inside the cochlea pushes and pulls the hair cells attached to the thin basilar membrane, which transduce the vibrations into neural impulses. The auditory nerve then carries the neural impulses to the brain.

28. Theories of Hearing Frequency theory seems to be a good explanation of how we hear low-frequency tones (lower than 500 Hz), but place theory better describes the way in which tones with frequencies higher than 1,000 Hz are heard. Both frequency and location are involved when we hear sounds with frequencies between 500 and 1,000 Hz. Frequency theory seems to be a good explanation of how we hear low-frequency tones (lower than 500 Hz), but place theory better describes the way in which tones with frequencies higher than 1,000 Hz are heard. Both frequency and location are involved when we hear sounds with frequencies between 500 and 1,000 Hz.

29. Balance and Movement Kinesthetic Sense: the sense providing information about (1) the position and movement of body parts in relation to each other and (2) the movement of the entire body or its parts. Information provided by the kinesthetic sense is detected by sensory receptors in the joints, ligaments, and muscles. As a result, we are usually able to maintain control of our bodies without visual feedback or a studied, conscious effort. Information provided by the kinesthetic sense is detected by sensory receptors in the joints, ligaments, and muscles. The visual and kinesthetic systems work with the vestibular sense to enable you to execute smooth, coordinated movements. Information provided by the kinesthetic sense is detected by sensory receptors in the joints, ligaments, and muscles. The visual and kinesthetic systems work with the vestibular sense to enable you to execute smooth, coordinated movements.

30. Balance & Movement The vestibular sense organs are located in the semicircular canals and the vestibular sacs in the inner ear. Vesibular Sense: the sense that provides information about the body�s orientation in space. Semicircular Canals: three fluid-filled tubular canals in the inner ear that sense the rotation of the head. The vestibular sense organs are located in the semicircular canals and the vestibular sacs in the inner ear. You sense the rotation of your head in any direction because the movement sends fluid coursing through the tubelike semicircular canals in the inner ear. The moving fluid bends the hair cell receptors, which, in turn, send neural impulses to the brain. The vestibular sense organs are located in the semicircular canals and the vestibular sacs in the inner ear. You sense the rotation of your head in any direction because the movement sends fluid coursing through the tubelike semicircular canals in the inner ear. The moving fluid bends the hair cell receptors, which, in turn, send neural impulses to the brain.

31. You sense the rotation of your head in any direction because the movement sends fluid coursing through the tubelike semicircular canals in the inner ear. The moving fluid bends the hair cell receptors, which, in turn, send neural impulses to the brain.

32. Smell Olfaction: the sense of smell. Olfactory Epithelium: two 1-square-inch patches of tissue, one at the top of each nasal cavity, which together contain about 10 million olfactory neurons, the receptors for smell.

33. Olfactory System Orbitofrontal Cortex: interprets olfactory information. Olfactory Bulb: receives information from odor receptor cells. Thalamus: relays olfactory information from olfactory bulb to orbitifrontal cortex. Nasal Mucosa: protective layer of tissue. Olfactory Receptor Cells: react to odor molecules. Olfactory Epithelium: site of olfactory receptor cells.

34. Olfactory System Odor molecules travel up the nostrils to the olfactory epithelium, which contains the receptor cells for smell. Axons of these olfactory receptors form the olfactory nerve. The olfactory nerve relays smell messages to the olfactory bulbs, which pass them on to the amygdala and olfactory cortex. From there, they go to the limbic system, the thalamus, and the orbitofrontal cortex.

35. The Primary Taste Sensations Unmai: is triggered by the substance glutamate, which in the form of monosodium glutamate (MSG), is widely used as flavoring in Asian foods. Many protein-rich foods such as meat, milk, aged cheese, and seafood contain glutamate.Unmai: is triggered by the substance glutamate, which in the form of monosodium glutamate (MSG), is widely used as flavoring in Asian foods. Many protein-rich foods such as meat, milk, aged cheese, and seafood contain glutamate.

36. Taste Taste Buds: structures along the sides of many of the tongue�s papillae that are composed of 60 to 100 receptor cells for taste.

37. Tactile Tactile: the sense of touch. Tactile information is conveyed to the brain where an object touches and depresses the skin, stimulating one or more of the several distinct types of receptors found in the nerve endings. These sensitive nerve endings in the skin send the touch message through the nerve connections to the spinal cord. The message travels up the spinal cord and through the brain stem and the midbrain, finally reaching the somatosensory coretx. Once the somatosensory cortex has been activated, you become aware of where and how hard you have been touched. Somatosensory Cortex: is the strip of tissue at the front of the parietal lobes where touch, pressure, temperature, and pain register.Somatosensory Cortex: is the strip of tissue at the front of the parietal lobes where touch, pressure, temperature, and pain register.

38. Pain Gate Control Theory: The theory that an area in the spinal cord acts as a gate that either blocks or transmits pain messages to the brain Pain Management Endorphins:The body�s own natural painkillers, which block pain and produce a feeling of well-being. Pain can be a valuable warning and a protective mechanism, motivating people to tend to an injury, to restrict activity, and to seek medical help. Negative thinking can influence the perception of pain. Pain can be a valuable warning and a protective mechanism, motivating people to tend to an injury, to restrict activity, and to seek medical help. Negative thinking can influence the perception of pain.

39. Factors that Contribute to Perceptual Processes (3) Attention: the process of sorting through sensations and selecting some for further processing Intentional Blindness: the phenomenon in which we shift our focus from one object to another, failing to notice changes in objects to which we are not directly paying attention Cross-Modal Perception: a process whereby the brain integrates information from more than one sense Attention enables the brain to focus on some sensations while screening others out. Unattended stimuli may be missed altogether or incorrectly perceived. Crossmodal perception depends on the comparative accuracy of the conflicting sensations. Attention enables the brain to focus on some sensations while screening others out. Unattended stimuli may be missed altogether or incorrectly perceived. Crossmodal perception depends on the comparative accuracy of the conflicting sensations.

40. Prior Knowledge Bottom-Up Processing: information processing in which individual components or bits of data are combined until a complete perception is formed. Top-Down Processing or concept driven processing: information processing in which previous experience and conceptual knowledge are applied to recognize the whole of a perception and thus easily identify the simpler elements of that whole. Perceptual Set: an expectation of what will be perceived, which can affect what actually is perceieved. Individuals use bottom-up and top-down processing to apply their prior knowledge to perceptual problems. Bottom-up processing is information processing in which individual components or bits of data are combined until a complete perception is formed. Top-down processing is information processing in which previous experience and conceptual knowledge are applied to recognize the whole of a perception and thus easily identify the simpler elements of that whole. Individuals use bottom-up and top-down processing to apply their prior knowledge to perceptual problems. Bottom-up processing is information processing in which individual components or bits of data are combined until a complete perception is formed. Top-down processing is information processing in which previous experience and conceptual knowledge are applied to recognize the whole of a perception and thus easily identify the simpler elements of that whole.

41. Gestalt Principles of Perceptual Organization Gestalt: a German word that roughly refers to the whole form, pattern, or configuration that a person perceives. Figure-Ground: one object (the figure) seems to stand out from the background (the ground) Similarity: objects with similar characteristics are perceived as units. Proximity: objects that are close together are perceived as units. Continuity: objects that appear to form a pattern are perceived as units. Continuation occurs when the eye is compelled to move through one object and continue to another object. Closure: figures with missing parts are perceived as whole figures.

42. Perceptual Constancy Perceptual Constancy is the tendency to perceive objects as maintaining the same size, shape, and brightness, despite changes in lighting conditions or changes in the retinal image that result when an object is viewed from different angles and distances. Size Constancy: as objects or people move father away, you continue to perceive them as being about the same size. Shape Constancy: the shape or image of an object projected onto the retina changes according to the angle from which it is viewed. Brightness Constancy: normally see objects as maintaining a constant level of brightness, regardless of the differences in lighting conditions.

43. Depth Perception Depth Perception: the ability to perceive the visual world in three dimensions and to judge distances accurately Binocular Depth Cues: depth cues that depend on both eyes working together.

44. Depth Perception: Convergence Convergence: occurs when the eyes turn inward to focus on nearby objects---the closer the object, the more two objects appear to come together. Hold the tip of your finger about 12 inches in front of your nose and focus on it. Now, slowly begin moving your finger toward your nose. Your eyes will turn inward so much that they virtually cross when the tip of your finger meets the tip of your nose.

45. Depth Perception: Retinal Disparity Fortunately, our eyes are just far enough apart, about 2 � inches or so, to give each eye a slightly different view of the objects being focused on and consequently, a slightly different retinal image. The difference between the two retinal images, know as binocular disparity (or retinal disparity). The farther away from the eyes (up to about 20 feet or so) the objects being viewed, the less disparity, or difference, between the retinal images. The brain integrates the two slightly different retinal images and creates the perception of three dimensions.

46. Depth Perception: Monocular Depth Cues Monocular Depth Cues: depth cues that can be perceived by one eye alone. Interposition Linear Perspective Realtive Size Texture Gradient Atmospheric Prespective (Areial perspective) Shawdow or Shading Motion Parralax

47. Monocular Depth Cues: Interposition Interposition: when one object partly blocks your view of another, you perceive the partially blocked object as being father away.

48. Monocular Depth Cues: Linear Perspective Linear Perspective: parallel lines that are known to be the same distance apart appear to grow closer together, or converge, as they recede into the distance.

49. Monocular Depth Cues: Relative Size Relative Size: larger objects are perceived as being closer to the viewer and smaller objects as being farther away.

50. Monocular Depth Cues: Texture Gradient Texture Gradient: Objects close to you appear to have sharply defined features, and similar objects that are farther away appear progressively less well defined or fuzzier in texture.

51. Monocular Depth Cues: Atmospheric Perspective Atmospheric Perspective: (sometimes called aerial perspective). Objects in the distance have a bluish tint and appear more blurred than objects close at hand.

52. Monocular Depth Cues: Shadow or Shading Shadow or Shading: When light falls on objects, they cast shadows, which add to the perception of depth.

53. Monocular Depth Cues: Motion Parralax Motion Parallax: When you ride in a moving vehicle and look out the side window, the objects you see outside appear to be moving in the opposite direction and at different speeds; those closest to you appear to be moving faster than those in the distance. Objects very far away, such as the moon and the sun, appear to move in the same direction as the viewer.

54. Perception of Motion The brain perceives real motion by comparing the movement of images across the retina to information derived from the spatial orientation senses. Apparent motion is the result of a psychological response to specific kinds of stimuli, such as flashing lights. The brain may also mistakenly perceive eye movement as object movement.

55. Perception of Motion Phi Phenonmeon/Stroboscopic Motion When several stationary lights in a dark room are flashed on and off in sequence, participants perceive a single light moving from one spot to the next. This type of illusion is called the phi phenomenon (sometimes called stroboscopic motion). Autokinetic Illusion If you stare at a single unmoving light in a dark room for a few seconds, the light will appear to begin moving, a phenomenon called the autokinetic illusion. If you look away from the light and then return to watching it, it will again appear to be stable.

56. Ponzo Illusion The Ponzo illusion (image at far right) also plays an interesting trick on our estimation of size. Contrary to your perceptions, bars A and B are the same length. Perceptions of size and distance, which we trust and which are normally accurate in informing us about the real world, can be wrong.

57. M�ller-Lyer Illusion Illusion: a false perception or a mispresentation of an actual stimuls in the envirnment. In the M�ller-Lyer illusion (see image at second from right) the two lines are the same length, but the diagonals extending outward from both ends of the upper line make it look longer than the lower line, which has diagonals pointing inward.

58. Subliminal Perception Subliminal Perception: the capacity to perceive and respond to stimuli that are presented below the threshold of awareness.

59. Extrasensory Perception (ESP) Extrasensory Perception (ESP): Gaining information about objects, events, or another person�s thoughts through some means other than the known sensory channels. Researchers have not been able to replicate the small number of experiments that support its existence.Researchers have not been able to replicate the small number of experiments that support its existence.

60. Synesthesia Synesthesia: the capacity for experiencing unusual sensations along with ordinary ones.

61. Subliminal Advertising The birth of subliminal advertising as we know it dates to 1957 when a market researcher named James Vicary inserted the words "Eat Popcorn" and "Drink Coca-Cola" into a movie. The words appeared for a single frame, allegedly long enough for the subconscious to pick up, but too short for the viewer to be aware of it. The subliminal ads supposedly created an 18.1% increase in Coke sales and a 57.8% increase in popcorn sales. Vicary's results turned out to be a hoax. But more recent experiments have shown that subliminal messages actually can affect behavior in small ways.

62. Subliminal Advertising A Harvard study from 1999 employed a similar method to Vicary's -- subjects played a computer game in which a series of words flashed before them for a few thousandths of a second. One set got positive words like "wise," "astute," and "accomplished." The other set got words like "senile," "dependent," and "diseased.� Despite the fact that these words flashed far too quickly to be consciously perceived, those who received positive words exited the room significantly faster than those who got negative.