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Canada (158,028)
Psychology (9,541)
PSYA01H3 (1,192)
Steve Joordens (1,048)


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University of Toronto Scarborough
Steve Joordens

PSYA01H3 2010-11-24 CHAPTER 6: SENSATION Sensory Processing N Sensation: the detection of the simple properties of a stimulus N Perception: the detection of the more-complex properties of a stimulus, including its location and nature Includes both animate and inanimate objects, as well as their backgrounds and movements N According to the above definitions, seeing the colour red is a sens. and recognizing a red apple is perc. N Traditionally there are five named senses, however, there are many more in reality N The task of the sense organs is to transmit signals to the brain that are coded in such a way as to represent certain features of events that have occurred in the environment N The task of the brain is so analyze this information and decide what has occurred N Transduction: the process by which the sense organs convert energy from environmental events (physical stimulus) into neural activity (the activity of receptor cells of sensory organs) N Receptor cell: a neuron that directly responds to a physical stimulus, such as a light, vibrations, or aromatic molecules N In the somatosenses, dendrites of neurons respond directly to physical stimuli without the intervention of specialized receptor cellsLhowever, some of these neurons have specialized endings that enable them to respond to particular kinds of sensory information N Types of energy transduction: radiant energy, mechanical energy, recognition of molecular shape, thermal energy, chemical energy N A code is a system of signals representing information as long as we know the rules of a code, we can convert a message from one medium to another without losing any information N Anatomical coding: a means by which the nervous system represents information; different features are coded by the activity of different neurons Interprets the location and type of sensory stimulus by which incoming nerve fibres are active Allows the brain to distinguish among stimuli of the same and well as different sensory modalities N Temporal coding: a means by which the nervous system represents information; different features are coded by the pattern of activity of neurons (in terms of time) The rate at which neurons are fired determines the intensity of the stimulation N Psychophysics: a branch of psychology that measures the quantitative relation between physical stimuli and perceptual experience 1 www.notesolution.comPSYA01H3 2010-11-24 N LZJ[Zjust-noticeable-difference (jnd): the smallest difference between two similar stimuli that can be distinguishedLa.k.a. difference threshold The jnd is directly related to the magnitude of the existing stimulus Weber fractions: the ratio between a just-noticeable difference and the magnitude of a stimulus; reasonably constant over the middle range of most stimulus intensities N Gustav Fechner, German physiologist, measured the absolute magnitude of perceptual experience in jnds N Threshold: the point at which a stimulus, or a change in the value of a stimulus, can just be detected N Difference threshold: another name for just-noticeable-difference; the minimum detectable difference between two stimuli The point at which the difference is detected 50% of the time N Absolute threshold: the minimum intensity of a stimulus that can be detected (discriminated from no diff) The point at which a participant detects the stimulus 50% of the time N Signal-detection theory: a mathematical theory of the detection of stimuli, which involves discriminating a Z]2Lo}KZL}]Z]LZ] Z]]ZKLZ] ZlZ]L} }LZE Z[]oo]L2LZZ}} detecting the signal }LZ]ZZ}LZ]ZL}o[Z]oo]L2LZZ}} ]L2Z]2Lo Hits and negatives are positive; misses and false alarms are negative L}}L}o[ZZ}LZ]ZZ ]L2Z]ZZZ}oZ} ]}L7Z Zs purposely manipulate this bias Receiver-operating-characteristic curve (ROC curve): a graph of hits and false alarms of subjects L]LK}]]}Lo }L]]}LZ8]L] Z}o[Z]o]} ] oZ]KoZ Detectability is measured by the relative distance of the curves from a 45 line @ZZZ}K]LZ}L[ZZLZ]]]}Z} L }] ostimulus Emphasizes that perceptual experience involves factors other than the activity of the sensory systems, factors such as motivation and prior experience Details of the Human Eye N The eye is sensitive to light; a radiant energy similar to radio waves that oscillates as it is transmitted from its sourceLthe wavelength is the distance between adjacent waves of radiant energy @Z o]KLZ]}L}Z]Z]Z]}L[ZK}Z o}ZoZZ} ] }L }oL2Z N The entire spectrum of wavelengths is known as the electromagnetic spectrumLthe part our eyes can detect (the part we see as light) is known as the visible spectrum 2 www.notesolution.com
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