PSYCH 1101: CHAPTER 6 SENSATION AND PERCEPTIONSENSING THE WORLD- Bottom up processing: sensory analysis that starts at an entry levelo Mind interpret what our senses detect o Will detect lines, angles, etc- Top Down processing: our previous experiences and encounters that we incorporate into perceptiono Notice the painting title, and the relative meaning of aspects of the paintingo Use existing tools to interpret the environment- Thresholdso Psychophysics: physical energy we can detect and its effect on our psychological effect o Absolute Thresholds: the minimum stimulus necessary to detect light, sound, touch or pressure 50% of the time To determine threshold, multiple tests (like the beeping test) can be used The absolute threshold increases with age as you detect lesso Signal detection Detecting the stimulus depends on psychological state (experience, alertness) as well as signal strength Signal detection theory: detects when we will detect weak signals- Researchers of this kind want to determine why people respond differently to same stimuli Signal detection is important because can weed life and death situations apart- Ex: airport terminal- Experience improves signal detection (for specific signal)o Subliminal Stimulation Subliminal: stimulus below our conscious threshold Because absolute threshold is fifty percent of the time, sometimes can detect stimulus lower than threshold An invisible image can prime people for reactions- Ex: the flash of neg or pos image and the disposition of people that followed Proves that most of our information processing is done unconsciously o Different thresholds The difference threshold is the ability of a hiuman to detect the difference between 2 stimuli (of the same origin i.e. light or sound) 50% of the time Weber’s law- For their difference (stimuli) to be different, two stimuli must differ on a constant proportion- not a constant amount- Sensory Adaptationo Diminishing sensitivity to an unchanging stimulus Olfactory fatigueo Give us the freedom to focus on novel and informative stimuluso Making us not perceive the world as it is, but as it is useful to usVISION- Our body tranduces (transform) light energy into neural signals for our brains to interpret- The stimulus input: light energyo The pulses of light energy is what strikes our eyeo We view a short range of visible light on the electromagnetic spectrumo Intensity: the amount of energy in a light wave, determined by amplitude o Hue: the color of the perceivable light - The eyeo Light enters the eye through the cornea (which protects the eye and bends the light to focus)o The light then passes through the pupil which is controlled by the iriso The iris dilates or constricts in response to light intensity, or energyo Behind the pupil sits the lens that focuses (accommodates) the incoming light rayson the fovea and retinao The retina is filled with light detecting cells that convert the light into neural signals and sends to the brain- The retinao Rods: black and white Located in the periphery and are better used in dim lighting Much more abundant at almost double the amount of cone cellso Cones: color Centralized in fovea and some even have specific nerves to send impulses to the brain without the optic nerve Allow to see detail more clearlyo The light activates these bipolar cells to produce chemical signals that activate ganglion cellso As the ganglion cells converge they form the optic nerve Carries the info to the thalamus which divides up the informationo Where the optic nerve leaves the eye there is a blind spot - Processing Visual Informationo Feature detection Feature detectors: located in the visual perception lobe, occipital lobe, theyallow us to recognize the angles and shapes that make up a specific scene Then sends the signals of recognized features to supercell clusters that analyze and make sense of these complex patterns - Ex: temporal lob supercell cluster allows us to see faceso Parallel processing The processing of many aspects of a problem simultaneously; the brain’s natural mode of information processing for many functions, including vision. Contrasts with the step by step or serial processing of most computers and of conscious problem solving Blindsight: when part of the occipital is missing, people cannot see a certain region in the field of vision- Are able to anticipate a color or direction in this missing area, but cannot see it Four aspects of vision are color, motion, form, and depth- If cannot see one, others can interpret the imageo Color vision The perception of color exists due to the light it reflects (it absorbs all otherlight forms) Color is perceived by the theater of our brains, and it our brains interpretation Young-hemholtz trichromatic theory:- All colors are made up of 3 primary colors- The retina in response has 3 types of color cells (red, green and blue)o When red and green are stimulated, we see yellow- In colorblind people, the cells that are responsive to red, blue or green are damaged- In order to understand why we do not have yellow receptors: opponent process theoryo We see an afterimage, an opponent color or sortso We analyze light in terms of 3 sets of opponent colors Red-green Yellow-blue White-blacko The combination of varying response to light combine colors and create the imageHEARING- Our audition is reflecting of the range of the human voice- Vary adaptable and highly tuned to sound- The Stimulus Input: Sound Waveso The resulting waves of compressed and expanded air o The strength, or amplitude, determines the loudness of the stimuluso Frequency: the waves/s, or wavelength Determines the pitcho Measure sounds in decibels Every 10 decibels is a tenfold increase in intensityo The ear The produce is to tranform sound to neural impulse Out ear: channels the sound waves to the auditory canal to the eardrum Middle ear: transfers eardrums vibrations to the bones (pistons) and to the cochlea Inner ear: the cochlea that transforms sound to neural impulse- Fluid filled and lined with hairlike process that response to the vibrating basilar membrane- Transfers to auditory nerve to auditory cortex (temporal lobe) Ringing attunes us to possible damage to the ear o Perceiving loudness The brain can perceive loudness via the number of activated cells People with hearing damage can only hear loud noise because hair cell loses
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