Chapter 5: Sensation and Perception Notes PDF

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Vocabulary words of chapter 5 (sensation and perception) from the textbook bolded and summarized....

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Chapter 5: Sensation and Perception 5.1: Sensation versus Perception ●

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Sensation: When sensory information is detected by a sensory receptor ○ Transduction: the conversion of sensory stimulus energy to action potential ○ Absolute threshold: minimum amount of the stimulus energy that must be present for the stimulus to be detected 50% of the time. ○ Subliminal messages: Messages that are presented below the threshold for conscious awareness ○ Just noticeable difference (jnd) or difference threshold: how much difference in stimulus is required to detect a difference Perception: the way sensory information is organized, interpreted, and consciously experienced. ○ Bottom-up processing: sensory information from a stimulus in the environment driving a process ■ Think: information travels UP to the brain to drive the process ○ Top-down processing: knowledge and expectancy driving a process ■ Think: information travels DOWN from the brain to drive it ■ Goal directed, slow, deliberate, effortful and under your control ○ Sensory adaptation: we don’t perceive stimuli that remain relatively constant over prolonged periods of time ■ Example: nose blindness: don’t smell the stink after being exposed to it for a while ○ Inattentional blindness: failure to notice something that is completely visible because the person was actively attending to something else and did not pay attention to other things ○ Signal detection theory: the ability to identify a stimulus when it is embedded in a distracting background ○ Muller-Lyer illusion: lines (especially in construction) appear to be different lengths when in reality they are the same length)

5.2: Waves and Wavelengths: ● ● ●

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Amplitude: the distance from the center line to the top point of the crest of the bottom point of the trough Wavelength: the length of a wave from one peak to the next Frequency: number of waves that pass a given point in a given time period and is often expressed in terms of Hertz (Hz) ○ Hertz (hz): cycles per second Visible spectrum: portion of the electromagnetic spectrum that we can see ○ Electromagnetic spectrum: encompasses all of the electromagnetic radiation that occurs in our environment and includes gamma rays,

Chapter 5: Sensation and Perception

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x-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves ■ Red: longer wavelengths, Violet: shorter wavelengths ■ Amplitude of waves: brightness/intensity of color ● Higher amplitude, brighter the color The frequency of a sound wave is associated with our perception of that sound’s pitch. ○ High frequency sound waves are perceived as high-pitched sounds The loudness of a given sound is closely associated with amplitude of a sound wave ○ Higher amplitudes are associated with louder sounds ○ Loudness is measured in terms of decibels (dB)

5.3: Vision: ●

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Cornea: transparent covering over the eye ○ Serves as a barrier between the inner eye and the outside world, ○ Involved in focusing light waves that enter the eye Pupil: the small opening in the eye through which light passes ○ The size of the pupil can change as function of the light levels as well as emotional arousal ○ When light levels are low the pupil will become dilated (expanded) ■ Allows more light to enter the eye ○ When light levels are high the pupil will constrict (smaller) ■ Reduces the amount of light entering the eye ○ Iris: Colored portion of the eye that controls the pupil’s size Lens: curved transparent structure that serves to provide additional focus ○ Attached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects Fovea: small indentation in the back of the eye (retina) which the lens focus images onto ○ Cones: specialized types of photoreceptor cells that work best in bright light conditions. Cones are very sensitive to acute detail and provide tremendous spatial resolution. Involved in ability to perceive colors. ○ Retina: light sensitive lining of the eye ■ Rods: specialized photoreceptor cells that work well in low light conditions, lack in spatial resolution and color function. Involved in our vision in dimly lit environments as well as our perception of movement on the periphery of our visual field Optic Nerve: Carries visual information from the retina to the brain. ○ formed by axons from the retinal ganglion cells converge and exit through the back of the eye

Chapter 5: Sensation and Perception Blind Spot: a point in the visual field where even when light from a small object is focused on the blind spot, we do not see it. ○ Optic Chiasm: a point where the optic nerve from each eye mergest just below the brain ■ X-shaped structure that sits below the cerebral cortex at the front of the brain. ■ At this point, information from the right visual field (which comes from both eyes) is sent to the left side of the brain. Information from the left visual field is sent to the right side of the brain Color Vision ○ Trichromatic theory of color vision: all colors in the spectrum can be produced by combining red, green and blue light. ■ Three types of cones are each receptive to one of the colors. ○ Opponent-process theory: color is coded in opponent pairs: black-white, yellow-blue and green-red. Some cells of the visual system are excited by one of the opponent colors and inhibited by the other. ■ After image: the continuation of a visual sensation after removal of the stimulus (negative colors) Depth perception: our ability to perceive spatial relationships in three-dimensional space ○ Binocular cues: rely on the use of both eyes ■ Binocular disparity: slightly different view of the world that each of our eyes perceive ○ Monocular cues: cues that require only one eye ■ Linear perspective: the fact that perceive depth when we see two parallel lines that seem to converge in an image ■ Interposition, partial overlap of objects, and relative size and closeness of images to the horizon ○

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5.4: Hearing: ●

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Outer ear: pinna, auditory canal, tympanic membrane ○ Pinna: visible part of the ear that protrudes from our heads ○ Tympanic membrane: ear drum Middle ear: 3 ossicles (tiny bones): malleus, incus, stapes ○ malleus (hammer) ○ Incus: (anvil) ○ Stapes (stirrup) Inner ear: semicircular canals (involved in balance and movement -- vestibular sense) and the cochlea

Chapter 5: Sensation and Perception Cochlea: fluid filled, snail-shaped structure that contains the sensory receptor cells (hair cells) of the auditory system How it works: ○ Sound waves travel along the auditory canal and strike the tympanic membrane causing it to vibrate. Vibration then moves 3 ossicles, which presses into a thin membrane of the cochlea known as the oval window. ○ Fluid inside cochlea begins to move, stimulates hair cells ■ Hair cells: auditory receptor cells of the inner ear embedded in the basilar membrane ■ Basilar membrane: thin strip of tissue within the cochlea ○ Activation of hair cells generates neural impulses that travel along the auditory nerve to the brain Pitch perception theories ○ Temporal theory: asserts that frequency is coded by the activity level of a sensory neuron. ■ Hair cells would fire action potentials related to the level of the sound wave. This can not account for the entire range. ○ Place theory: suggests that different portions of the basilar membrane are sensitive to sounds of different frequencies. ■ Base of basilar membrane = high frequencies ■ Tip of basilar membrane = low frequencies Sound Localization ○ Monaural cues: one eared cues used to localize sound ■ Identifying if sound comes from directly above, below, in front of behind ○ Binaural cues: two eared cues used to localize sound ■ Location of sound along the horizontal axis ■ Interaural level difference: the fact that a sound coming from the right side of your body is more intense at your right ear than at your left ear because of the attenuation of the sound wave as it passes through your head ■ Interaural timing difference: the small difference between in the time at which a given sound wave arrives at each ear (sounds on the right of you arrive at your right ear sooner than your left) Deafness: partial or complete inability to hear ○ Congenital deafness: born without hearing ○ Conductive hearing loss: problem delivering sound energy to the cochlea. ■ Blockage of the ear canal, hole in the tympanic membrane, problems with ossicles, fluid in the space between the eardrum and cochlea. ○

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Chapter 5: Sensation and Perception Sensorineural hearing loss: associated with failure to transmit neural signals from the cochlea to the brain ■ due to aging, head or acoustic trauma, infections and diseases, medications, environmental effects (noise exposure) ■ Meniere’s disease: results in the degeneration of the inner ear structures that can lead to hearing loss, tinnitus (constant ringing or buzzing), vertigo (a sense of spinning), and an increase in pressure within the inner ear ■ Can not be treated with hearing aids Cochlear implants: electronic devices that consist of a microphone, a speech process, and an electrode array. Receives incoming sound information and directly stimulates the auditory nerve to transmit information to the brain ○

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5.5: The other Senses ●

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Taste (Gustation): ○ 6 Groupings: Sweet, salty, sour, bitter, umami, fatty content ■ Umami: translates to yummy, associated with taste for monosodium glutamate ○ Taste buds: formed by groupings of taste receptor cells with hair-like extensions that protrude into the central pore of the taste bud. ■ Life cycle of 10 days to 2 weeks. Smell (Olfaction) ○ Olfactory receptor cells are located in the mucous membrane at the top of the nose. Small hair-like extensions from these receptors serve as the sites for order molecules dissolved in the mucus to interact with chemical receptors located on these extensions. ○ Olfactory bulb: a bulb-like structure at the tip of the frontal lobe where the olfactory nerve begins. ■ Once an order molecule has bound a given receptor a chemical changes within the cell result in signals being sent to the olfactory bulb Pheromones: chemicals sent by another individual Touch, Thermoception and Nociception ○ Receptors that are distributed through the skin that respond to various touch-related stimuli: ■ Meissner’s corpuscles: respond to pressure and lower frequency vibrations ■ Pacinian corpuscles: detect transient pressure and higher frequency vibrations ■ Merkel’s disks: respond to light pressure ■ Ruffini corpuscles: detect stretch

Chapter 5: Sensation and Perception Nerve endings respond to: ■ Thermoception: temperature perception ■ Nociception: a signal indication potential harm and maybe pain Pain Perception ○ Inflammatory pain: pain that signals some type of tissue damage ○ Neuropathic pain:j pain resulting from damage to neurons of either peripheral or central nervous system. Pain signals are then sent to the brain get exaggerated ○ Congenital insensitivity to pain (congenital analgesia): born without the ability to feel pain. Can detect differences in temperature and pressure, they can not experience pain. Significant injuries are often experienced. Vestibular Sense: contributes to our ability to maintain balance and body posture ○ Major sensory organs are located next to the cochlea in the inner ear ○ Proprioception: perception of body position ○ Kinesthesia: perception of the body’s movement through space ○

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5.6: Gestalt Principles of Perception ●

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Gestalt Psychology: brain creates a perception that is more than simply the sum of available sensory inputs ○ Figure-ground relationship: we tend to segment our visual world into figure and ground. Figure is the object and ground is the background. ■ Face/vase illusion, depends on what you consider to be the figure and what you consider to be the ground ○ Proximity: things that are close to one another tend to be grouped together ○ Similarity: things that are alike tend to be grouped together ■ Example: Football teams all wear the same color ○ Continuity (good continuation): we are more likely to perceive continuous, smooth flowing lines rather than jagged, broken likes ■ We perceive two lines intersecting as crossing as opposed to two lines that make sharp turns where they meet. ○ Closure: we organize our perceptions into complete objects rather than a series of parts ■ Circle made of dashed lines makes a circle, we do not just perceive the individual dashed lines Pattern perception: ability to discriminate between figures and shapes Perceptual hypothesis: educated guesses that we make while interpreting sensory information....