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SENSATION and PERCEPTION - Coggle Diagram
SENSATION and PERCEPTION
Sensory processes
The absolute threshold is the lowest level of a physical stimuli we can detecnt. Signal detenction theory has been used by psychophysicists to better measure how humans detect stimuli among noise in the environment, In the neuroal systems of perception and in their responses
The differene threshold is the amount by which two stimuli must differ for them to be percepived as different 50% of the time. The human sensory system can respond to variations in stimuli across huge ranges of variation.
Sensory sytem are particularly responsive to cahnges in stimulation, and adaptation occurs in response to unchanging stimuli
Multisensory processing: Brian imaging studies have shown us that the brain starts to integrate sensory information even at the level of primary visual, auditory and somatosensory cortex. We also know that the primary sensory corties interact with one another even before sensory information has been fed up to later stages of brain processing
The sensory systems
Sound waves have two characteristics: frequency and amplitude. Frequency is related to pitch, amplitude to loudness Loudness is coded in terms of the number and types of auditory nerve fibres that fire. Pitch is coded in two ways- Low-frequency tones are coded in terms fo corresponding numbers of nerve impulses in individual receptors or by volleys of impulses from a number of receptors. Frequencies above 4000mhz are coded according to the regions of the basilar membrane that is desplaed most by the fluid wove in the cochlear canal
Hearing loss may result from the conduction deafness produced by problems involving the structures of the ear that transmit vibrations to the cochlea, or from nerve deafness in which the receptors in the cochela or the auditory nerve are damaged
The receptors of taste and smell respond to chemical molecules. Taste buds are responsive to same basic qualities including sweet, sour, salty, bitter and umami. The recptors of smell are long cells in the upper nasal cavity. It turns out that humans have a remarkable sensitivity to smells and can distinguish more than a trillion odours
Touch includes cutaneous tactile sensation in the skind, and proprioceptive input from the muscles, tendons and joints. Touch perform a remarkable range of different functions, including haptics and body sensing
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Perception of constant objects: depth, distance and movement
Perceptual constancies allow us to recognize familiar stimuli under changning conditions. In te visual realm, there are three constancies: shape, lightness and size
Monocular cues to judge distance and depth include linear perspective, relative size, height in the horixontal plane, texture and clarity. Depth perception also occurs through the monocular cues of light and shadow patterns, interposition and motion parallax
Binocilar disparity occurs as slightly different images are viewed by each eye and acted on by featre detectors for depth. Convergence of the eyes provides a second binocular cue
The basis for pereption of movement is absolute movement of a stimulus across the retina or relative movement of an object in relation to tis background. Stroboscopic movement is illusory
Illusions are erroneous perceptions. They may be regarded as incorrect perceptual hypotheses. Perceptual constancies help produce many illusions, including the moon illusion and a variety of other context-produced illusions
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Experience, Critical periods and Perceptual development
Perceptual developmewnt involves both physical maturation and learning. Some pewrceptual abilities are innate or develop shortly after birthm whereas others require particular experiences early in life in order to develop
Cultural factors can influence certain aspects of perception, including picture perception and susceptibility to illusions. However, many aspets of pewrception seem constant across cultures
Visual-deprivations studies, manipulations of visual input and studies of restored vision have shown that the normal biological development of the perceptual system depends on certain sensory experiences at early peridos of development