Chapter 4 Sensation and Perception Sensory branding exploit all senses to promote product or brand Sensation and Perception are Distinct Activities Transduction Psychophysics simple stimulation of a sense organ taste touch smeel etc organization identifcation and interpretation of sensation in Sensation Perception order to form a mental representation when many sensors in body convert physical signals from environment into encoded neural signals sent to central nervous system methods that measure the strength of a stimulus and the observer s sensisitivity to that stimulus 50 of the time Just noticeable difference JND barely be detected Absolute threshold minimal intensity needed to just barely detect a stimulus minimal CHANGE in a stimulus that can just o Weber s law proportion despite variations in the intensity the just noticeable difference of a stimulus is a constant Signal detection theory response to a stimulus depends on both the person s sensitivity to the stimulus in the presence of noise and on a person s decision criterion represents sensory events how effectively the perceptual system o Perceptual sensitivity stimulus presented and observer says yes stimulus presented and observer says no Hit Miss False alarm Correct rejection Stimulus not presented but observer says yes stimulus not presented and observer says no Sensory adaptation over time as and organism adapts to current conditions sensitivity to prolonged stimulation tends to decline Vision I How the Eyes and the Brain Convert Light Waves into Neural Signals the ability to see fine detail Visual actuity 3 properties of light waves o Length hue color o Amplitude brightness o Purity of distinct wavelengths that make up the light How light enters the eye 1 Passes through clear smooth outer tissue called cornea 2 Cornea bends light waves and sends them through pupil a hole in the colored part of the eye a Colored part of the eye iris 3 Muscle inside the eye controls shape of lens 4 Light is focused on retina light sensitive tissue lining back of eyeball process by which eye maintain clear image on a Accomodation retina farsightedness nearsightedness Myopia Hyperopia Photoreceptor cells into neural impulses in retina o Cones see fine details contain light sensitive pigments that transduce light detect color operate under normal daylight condition allow us to o Rods o Fovea Bipolar cells active under low light condition for night vision area in retina where vision is clearest and there are no rods collect neural signals from rods and cones and transmit them to outermost layer of retina Retinal ganglion cells RCG s Color after image staring at 1 color too long organize signals and send them to brain o Color opponent system Area V1 part of the occipital lobe that contains visual cortex 2 pathways or visual streams from occipital cortex to visual areas pairs of visual neurons work in opposition 1 Ventral stream below 2 Dorsal stream above represents object s shape and identity location and motion of object Visual form agnosia inability to recognize objects by sight Vision II Recognizing What we Perceive Binding problem focused attention is not required to detect individual how features are linked together so that we see unified objects a perceptual mistake where features from multiple objects rather than free floating or miscombined features Illusory conjunction are incorrectly combined Feature integration theory feature that comprise a stimulus but it is required to bing those individual features together houses or even body parts Distributed representation identifies any viewed object constant even as sensory signals change perception remains specialized brain areas modules detect and represent faces Perceptual constancy Modular view patter of activity across multiple brain regions that Gestalt perceptual grouping rules when confronted with 2 or more possible interpretations of fill in missing elements of a visual scene o Simplicity o Closure o Continuity an object the simplest is likely interpreted grouped together perceived as belonging to same object as parts of a single moving object o Proximity o Common fate o Similarity object close together are grouped together edges or contours with the same orientation are generally regions similar in color lightness shape or texture are elements of a visual image moving together are perceived Perceptual grouping involves identifying a figure from its background ground relationship face vase mental representation directly compared to viewed shape in retinal Reversible figure Template image Theories of object recognition o Image based o Parts based Monocular depth cues viewed with only one eye o Linear perspective o Texture gradient makes them look smaller ones are higher o Interposition o Relative height image Binocular disparity about depth aspects of a scene that yield info about depth when parallel lines converge in distance view uniformly patterned surface and the distance 1 object blocks another so it is closer in front closer objects are lower in visual field and further difference in retinal images of eyes that provide information Ames room trapezoidal room looks square through peephole due to shapes of Apparent motion Water fall illusion windows and flooring person in right corner looks taller than person in left stare at downwards waterfall for awhile when looking at something not moving you ll experience upward motion aftereffect appearing in rapid succession in different locations scene Inattentional blindness attention perception of movements as result of alternation signals failure to perceive objects that are not the focus of occurs when people fail to detect changes to visual details of a Change blindness Audition More Than Meets the Ear 3 dimensions of sound waves o Frequency pitch o Amplitude loudness o Complexity timbre Flute vs trumpet Human ear divided into 3 parts 1 Outer ear collects sound waves and funnels toward middle ear a Pinna b Consists of auditory canal and eardrum visible part on outside of head 2 Middle ear transmits vibratives to inner ear a Contains 3 smallest bones in body ossicles i hammer anvil and stirrup 3 Inner ear transduces vibrations into neural impulses a Cochlea b Basilar membrane ossicles reach cochlear field fluid filled tube that is organ of auditory transduction structure undulates when vibrations from c Hair cells basilar membrane specialized auditory receptor neurons embedded in portion of the temporal lobe that contain the
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