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Psychology Exam2 Notes.docx

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Department
Psychology
Course Code
Psychology 1000
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Dr.Mike

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Psychology Chapter 5 Sensation and Perception - Sensation: the stimulus-detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain · stimulation of the sense organs · you LOOK with your eyes - Perception: making “sense” of what our senses tell us- is the active process of organizing this stimulus input and giving it meaning · selection, organization, and interpretation of sensory input. · you SEE with your brain - Psychophysics: the study of how physical stimuli are translated into psychological experience. - Synesthesia- mixing of senses ie if you experience light waves as sounds - Transduction- when your sensory receptors translate the message (whether the stimulus is light, sound waves etcs) it translate this information into the only language the nervous system understands : the language of nerve impulses.The characteristics of a stimulus are converted into nerve impulses - Functional MRI studies have shown that for people with synesthesia with word-colour linkages, hearing certain words is associated with neural activity in parts of the visual cortex - Sensory Integration · all the events happen very quickly Psychophysics: Basic Concepts - Stimulus: info in the environment that is picked up by the receptors in our nervous system - Sensation: begins with a detectable stimulus · how strong must a stimulus be before we can detect it? · FECHNER: the concept of threshold - Absolute threshold: · detected 50% of the time · Lowest intensity at which a stimulus can be detected correctly · Lower the absolute threshold the greater the sensitivity -Subliminal stimulus: one that is so weak or brief, although received by the senses, it cannot be perceived consciously, the stimulus is well below the absolute threshold - Difference threshold · The minimal amount the stimulus needs to be increased (or decreased) to be judged as different from the original stimulus. Figure 1 sensory integration · The smallest difference between two stimuli that people can perceive 50% of the time · The difference threshold is sometimes called the just noticeable difference (JND) - Weber’s law: the difference threshold or (JND) is directly proportional to the magnitude of the stimulus with which the comparison is being made · Expressed as a WEBER FRACTION (constant value) · Ie the jnd value for weights is a weber fraction of approximately 1/50. This number means that if you lift a weight of 50 grams, a comparison weight must weigh at least 51 grams in order for you to be able to judge it as heavier. If the weight were 500 grams, a second weight would have to weigh at least 510 grams. (1/50 = 10/500) for you to discriminate between them Sensory Adaption - Sensory adaptation: initially you will feel, but eventually it will become familiar and you won’t notice it. Changes in our environment are often most newsworthy, sensory systems are finely attuned to changes in stimulation. Sensory neurons are engineered to respond to a constant stimulus by decreasing their activity, and the diminishing sensitivity to an unchanging stimulus is called the sensory adaptation - Subliminal stimuli: attend to new stimuli in the environment, weak or brief that, although it is received by the senses, it cannot be perceived consciously- the stimulus is well below the absolute threshold - Research Findings · Little effect on behavior · Only small effect on attitudes Audition - The stimuli for our sense of hearing are sound waves, a form of mechanical energy - Sounds waves= pressure waves in air, water or some other conducting medium · Frequency: number of sound waves (cycles/second)  pitch · Amplitude: vertical size of the sound waves, the amount of compression and expansion of the molecules in the conducting medium  loudness - Auditory Transduction: from pressure waves to nerve impules · The transduction system of the ear is made up of tiny bones, membranes, and liquid-filled tubes design to translate pressure waves into nerve impulses · ear divided into middle, inner and outer - higher note= larger the frequency - Hammer= attached firmly to the eardrum and the stirrup is attached to another membrane, the oval window, which forms the boundary between the middle ear and the inner ear. The inner ear contains he cochlea, a coiled, snail shape tube that is filled with fluid and contains he basilar membrane, a sheet of tissue that runs its length - Auditory cortex= located in the temporal lobe Middle ear - sound waves put pressure Vestibular System - diagram · semicircular canals (first three arrows) Perception of loudness - 1. More neurotransmitter substance is released - 2. Certain cells only respond to very loud sounds Perception of Pitch - Frequency theory · Eg: sound of 100 Hz (i.e. 100 cycles/second) neurons would fire 100x/second - Place theory: different frequencies stimulate different areas on basilar membrane · Low frequency trigger a wave at the tip of cochlea Perception of Sound - Pressure waves · Cochlea · Auditory nerve · Brainstem · Thalamus (MGN) · auditory cortex - Perception of Sound Tonotopic Organization - And these neurons are organized tontopically · Having two ears is important - 2 ears are better than once · Intensity · Time of arrival · (harder to hear from sources producing the sound at equal distance from both ears) Gustation - in saliva and cause neural firing (routed to the thalamus) - tongue receptors (change every month) - tip of tongue detect sweet (glucose and carbohydrates= lots of energy, good food source) Olfaction - tiny receptors for smell (olfactory cilia): hair-like structures in the nasal passage - directly synapses with the olfactory tract in the brain - not routed first to the thalamus Sense of Touch - stimuli at centre have opposite effect of stimuli falling outside of the centre - primary somatosensory cortex · diagram  motor cortex  somatosensory cortex  posterior parietal cortex (touch) · the greater the sensibility, the greater the brain area (?) Feeling pain - receptors · free nerve endings in the skin · two different types for different types of pain · sharp (brief) vs dull (throbbing) · A-delta fiber are myelinated (fast processing info) - Survival function - Role of cognition · Negative thinking (makes pain a lot worse to endure) · Distraction (from pain, useful strategy) - Spinal cord can block pain signals to the brain Factors effecting pain perception - Biological · Stimulation of nerve endings
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