PSYCHOLOGY LECTURE NOTES III - Sensation What is sensation?...

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Sensation What is sensation? - how sensory organs respond to and detect external stimulus energy and how those responces are transmitted to the brain How is that different from perception? - brain’s further processing of detected signals and results in an internal representation Sensory Coding - Physical or chemical stimulus properties o Translated by sensory neurons and passed on as neural impulse to connecting neurons o This is called transduction - Types of sensory Coding o Quantitative direct relationship between intensity, brightness, loudness and frequency of neural firing o Qualitative different sensory receptors respond to particular stimulus features, usually coarse (broad) distinctions The Six Senses - Hearing sound waves - Vision light waves - Touch pressure on the skin - Pain wide variety of potentially harmful stimuli - Taste molecules dissolves in fluid on the tongue - Smell molecules dissolved in the mucous in the nose Psychophysics - psychological experience of physical sensations - Psychophysics o Sensory thresholds o Absolute minimum intensity of stimulation needed to evoke sensory experience o Difference minimum amount of change required to detect difference in intensity Weber’s Law - Just noticeable difference is relative to the size, intensity, etc. of the two stimuli being compared Sensory thresholds are relative - theories of absolute thresholds fail to account for human judgment - signal-detection theory – sensory experiments require judgment about presence or absence of stimuli Sensitivity to sensory information - Can be affected by judgment, cognitive set, biases - Adaptation decrease in sensory sensitivity with increased duration of exposure Basic Sensory Processes Taste receptors found in taste buds on tongue (Sweet, salty, sour, bitter and umami (MSG)) Airborne molecules (scents) enhance flavor. - Transmitted via cranial nerves to thalamus. - To other parts of the limbic system and some info passed on the cerebral cortex Smell olfactory receptors transmit impulses directly to olfactory bulb - heavily interconnected with the limbic system (emotions, memory formation) frontal lobes
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- pheromones – chemicals released by animals (including humans) that trigger physiological reactions but not detectable smells… Haptic Senses (Touch) touch, pressure, temperature, pain - pain sensitivity has high evolutionary value - fast and slow pain pathways Melzack and Wall - Gate control theory of pain - Messege from activated pain receptors must pass through neural “gate” in spinal cord - Gate can be closed by other haptic stimuli Sensation, Perception and Attention Part II The wave-detecting senses deal with information that hits us in wave form such as hearing and vision. -
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This note was uploaded on 04/18/2008 for the course PSYO 111 taught by Professor Rutherford during the Winter '08 term at UBC.

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PSYCHOLOGY LECTURE NOTES III - Sensation What is sensation?...

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